45406 + Interview Questions in Physics in Class 12 Page 2 InterviewSolution

51.	What contradiction is found by using ampere circuital law to obtain magnetic field during charging of capacitor ?
Answer» <html><body><p></p>Solution :In figure (a) parallel <a href="https://interviewquestions.tuteehub.com/tag/plate-1156364" style="font-weight:bold;" target="_blank" title="Click to know more about PLATE">PLATE</a> capacitor (C ) is shown in its charging state. During charging of capacitor at time t current i(t) flows which is obtained from battery. No current flow inside capacitor.<br/><img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/KPK_AIO_PHY_XII_P1_C08_E01_005_S01.png" width="80%"/><br/>A parallel plate capacitor C, as part of a circuit through which a time dependent current i(t) flows, (a) a loop of radius r, to determine magnetic <a href="https://interviewquestions.tuteehub.com/tag/field-987291" style="font-weight:bold;" target="_blank" title="Click to know more about FIELD">FIELD</a> at a point P on the loop , (b) a pot - shaped surface passing through the interior between the capacitor plates with the loop shown in (a) as its rim , (c ) a tiffinshaped surface with the circular loop as its rim and a flat circular bottom S between the capacitor plates. the circular bottom S between the capacitor plates. The arrows show uniform electric field between the capacitor plates.<br/>At a point P outside capacitor, consider loop of radius r whose centre is on the wire plane is perpendicular to wire.<br/>From symmetry it can be shown that at any point on the loop magnetic field is along circumference of the loop and magnitude is equal of at any point of the loop.<br/>By using ampere circuital law point P outside capacitor,<br/> `oint <a href="https://interviewquestions.tuteehub.com/tag/vec-723433" style="font-weight:bold;" target="_blank" title="Click to know more about VEC">VEC</a>(B).vec(d)l=mu_(0)i(t)` ....(1)<br/> where `Sigma I = i(t)` is total current.<br/>If `\|vec(B)\|=B`and `oint vec(d)l=2pir`, then<br/>`B(2pi r)=mu_(0)i(t)`...(2)<br/>Now consider another surface shown in figure (b) which do not touch current <a href="https://interviewquestions.tuteehub.com/tag/carrying-909956" style="font-weight:bold;" target="_blank" title="Click to know more about CARRYING">CARRYING</a> conductor bottom of surface lies in region between plates.<br/>Also in figure (c ) consider oval shaped surface which is between plates of capacitor and radius equal to r. In figure (b) and (c ) current do not flow in closed surface considered hence closed surface having radius r by using ampere circuital law.<br/> In `int vec(B).vec(d)l=mu_(0)Sigma I`<br/>`int dl=2pi r`<br/>`Sigma I=mu_(0)i(t)=0`<br/>Thus, we get different value of magnetic field outside and inside which is contradictory. Thus, outside and inside which is contradictory. Thus, outside plates of capacitor we get non - zero magnetic field and inside (between) plates of capacitor magnetic field is zero.<br/>This contradiction is by using ampere circuital law hence it can be said that there is something missing in ampere circuital law.</body></html>

Discussion

52.	The fraction of atoms of radioactive element that decays in 6 days is (7)/(8). The fraction that decays in 10 days will be
Answer» <html><body><p>`(<a href="https://interviewquestions.tuteehub.com/tag/77-335698" style="font-weight:bold;" target="_blank" title="Click to know more about 77">77</a>)/(<a href="https://interviewquestions.tuteehub.com/tag/80-337972" style="font-weight:bold;" target="_blank" title="Click to know more about 80">80</a>)`<br/>`(71)/(80)`<br/>`(31)/(<a href="https://interviewquestions.tuteehub.com/tag/32-307188" style="font-weight:bold;" target="_blank" title="Click to know more about 32">32</a>)`<br/>`(15)/(<a href="https://interviewquestions.tuteehub.com/tag/16-276476" style="font-weight:bold;" target="_blank" title="Click to know more about 16">16</a>)`</p>Answer :<a href="https://interviewquestions.tuteehub.com/tag/c-7168" style="font-weight:bold;" target="_blank" title="Click to know more about C">C</a></body></html>

Discussion

53.	A circuit consists of a resistance R connected to n similar cells. If the current in the circuit is the same whether the cells are connected in series or in parallel, then the internal resistancer of each cell is given by
Answer» <html><body><p>`<a href="https://interviewquestions.tuteehub.com/tag/r-611811" style="font-weight:bold;" target="_blank" title="Click to know more about R">R</a> = R//n`<br/> `r=nR`<br/>`r=R`<br/>`r= 1//R`</p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :<a href="https://interviewquestions.tuteehub.com/tag/c-7168" style="font-weight:bold;" target="_blank" title="Click to know more about C">C</a></body></html>

Discussion

54.	A uniform non conducting ring has mass m and radius R. tow point charges q and q' are fixed on its circumference at a separation of sqrt(2)R the ring remains in equilibrium in air with its plane vertical in a region where exists a uniform vertically upward electric field E. Given E=(4mg)/(7q) (a) Find angle theta in equilibrium position (see figure). (b) The ring is given a small rotation in the plane of the figure and released. Will it perform oscillations?
Answer» <html><body><p><br/></p>Answer :(a). `theta=tan^(-<a href="https://interviewquestions.tuteehub.com/tag/1-256655" style="font-weight:bold;" target="_blank" title="Click to know more about 1">1</a>)((<a href="https://interviewquestions.tuteehub.com/tag/3-301577" style="font-weight:bold;" target="_blank" title="Click to know more about 3">3</a>)/(<a href="https://interviewquestions.tuteehub.com/tag/4-311707" style="font-weight:bold;" target="_blank" title="Click to know more about 4">4</a>))` <br/> (<a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a>). Yes</body></html>

Discussion

55.	The time required for the light to pass through a glass slab (refractive index = 1.5) of thickness 4 mm is (c = 3 xx 10^(8)ms^(-1)"speed of light in free space")
Answer» <html><body><p>`10^(-<a href="https://interviewquestions.tuteehub.com/tag/11-267621" style="font-weight:bold;" target="_blank" title="Click to know more about 11">11</a>)`<br/>`2 xx 10^(-11) s`<br/>`2 xx 10^(11)s`<br/>`2 xx 10^(-5)s`. </p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :(b) We know, `n_(a) c_(a) = n_(g) c_(g)` <br/> `(n_(g))/(n_(a)) = (c_(a))/(c_(g))` <br/> `(3)/(2) = (3xx10^(8))/(c_(g))` <br/> `c_(g) = 2 xx 10^(8)` <br/> We have, Time = `("<a href="https://interviewquestions.tuteehub.com/tag/distance-116" style="font-weight:bold;" target="_blank" title="Click to know more about DISTANCE">DISTANCE</a>")/("Speed")` <br/> `t = (4 xx 10^(-3))/(2 xx 10^(8))` <br/> or "" `t = 2 xx 10^(-11) s.`</body></html>

Discussion

56.	What do you understand by "sharpness of resonance" in a series LCR circuit ? Find expression for Q-factor of the circuit.
Answer» <html><body><p></p>Solution :We <a href="https://interviewquestions.tuteehub.com/tag/know-534065" style="font-weight:bold;" target="_blank" title="Click to know more about KNOW">KNOW</a> that current amplitude in a series LCR circuit is maximum when `omega = omega_(0) = 1/sqrt(LC)`. The maximum value of current at resonance is `(I_(m))_(rms) = V_(m)/<a href="https://interviewquestions.tuteehub.com/tag/r-611811" style="font-weight:bold;" target="_blank" title="Click to know more about R">R</a>`For any other value of `omega` , the current amplitude is less. Choose values of o for which current amplitude is `1/sqrt(2) (I_(m))_(max)` . In Fig. 7.34, these values of <a href="https://interviewquestions.tuteehub.com/tag/ware-1448850" style="font-weight:bold;" target="_blank" title="Click to know more about WARE">WARE</a> represented by <a href="https://interviewquestions.tuteehub.com/tag/points-1157347" style="font-weight:bold;" target="_blank" title="Click to know more about POINTS">POINTS</a> B and C having angular frequencies `omega_(1)` and `omega_(2)`such that `omega_(1) = omega_(2)`and `omega_(2) = omega_(0) + Deltaomega`.The quantity `omega_(0)/(2.Deltaomega)`is regarded as a measure of sharpness of resonance and is also known as the Q-factor of the circuit. Smaller the value of Aw, sharper is the resonance.<br/> It can be easily calcualted that `Deltaomega = R/(2L)` <br/> <img src="https://doubtnut-static.s.llnwi.net/static/physics_images/U_LIK_SP_PHY_XII_C07_E10_010_S01.png" width="80%"/> <br/>`<a href="https://interviewquestions.tuteehub.com/tag/therefore-706901" style="font-weight:bold;" target="_blank" title="Click to know more about THEREFORE">THEREFORE</a>` Q-factor representing the sharpness of resonance <br/> `Q = (omega_(0))/(2Deltaomega) = (omega_(0)L)/R` <br/> As, `omega_(0) =1/sqrt(LC)`, hence, `Q = 1/sqrt(LC).1/R = 1/Rsqrt(L/C)`</body></html>

Discussion

57.	A transformer cannot be used to step up dc voltage. Why ?
Answer» <html><body><p></p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :A dc voltage is applied across the primary ,then the <a href="https://interviewquestions.tuteehub.com/tag/magnetic-551115" style="font-weight:bold;" target="_blank" title="Click to know more about MAGNETIC">MAGNETIC</a> flux <a href="https://interviewquestions.tuteehub.com/tag/linked-7276088" style="font-weight:bold;" target="_blank" title="Click to know more about LINKED">LINKED</a> with the coil does not <a href="https://interviewquestions.tuteehub.com/tag/vary-1443941" style="font-weight:bold;" target="_blank" title="Click to know more about VARY">VARY</a> with time end hence no emf is induced across the secondary.</body></html>

Discussion

58.	A stretched string is vibrating in the second overtone then the number of nodes and antinondes between the ends of the string are respectively :
Answer» <html><body><p>3 and 2 <br/>2 and 3 <br/>4 and 3<br/>3 and 4 </p>Solution :<a href="https://interviewquestions.tuteehub.com/tag/second-1197322" style="font-weight:bold;" target="_blank" title="Click to know more about SECOND">SECOND</a> overtone of <a href="https://interviewquestions.tuteehub.com/tag/stretched-7711564" style="font-weight:bold;" target="_blank" title="Click to know more about STRETCHED">STRETCHED</a> string <a href="https://interviewquestions.tuteehub.com/tag/means-1091780" style="font-weight:bold;" target="_blank" title="Click to know more about MEANS">MEANS</a> third <a href="https://interviewquestions.tuteehub.com/tag/harmonic-1015999" style="font-weight:bold;" target="_blank" title="Click to know more about HARMONIC">HARMONIC</a> so string vibrates in from of three loops . So number of nodes and atminodes between the ends are so correct <a href="https://interviewquestions.tuteehub.com/tag/choice-915996" style="font-weight:bold;" target="_blank" title="Click to know more about CHOICE">CHOICE</a> is (b). <br/> <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/MOD_RPA_OBJ_PHY_C10_E02_015_S01.png" width="80%"/></body></html>

Discussion

59.	The empty space between the shaded baals and holow balls and hollow balls as shown in the diagram is called
Answer» <html><body><p>hexagonal <a href="https://interviewquestions.tuteehub.com/tag/void-11409" style="font-weight:bold;" target="_blank" title="Click to know more about VOID">VOID</a><br/>octahedral void<br/>tetrahedral void<br/>Double triangular void</p>Solution :The <a href="https://interviewquestions.tuteehub.com/tag/given-473447" style="font-weight:bold;" target="_blank" title="Click to know more about GIVEN">GIVEN</a> <a href="https://interviewquestions.tuteehub.com/tag/arrangement-884592" style="font-weight:bold;" target="_blank" title="Click to know more about ARRANGEMENT">ARRANGEMENT</a> of <a href="https://interviewquestions.tuteehub.com/tag/spheres-1222120" style="font-weight:bold;" target="_blank" title="Click to know more about SPHERES">SPHERES</a> represents octahederal void</body></html>

Discussion

60.	What are the factors on which the rate of thermionic emission depends?
Answer» <html><body><p></p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :The rate of thermionicemission <a href="https://interviewquestions.tuteehub.com/tag/depends-948548" style="font-weight:bold;" target="_blank" title="Click to know more about DEPENDS">DEPENDS</a> on the temperature and work function of the metal. <a href="https://interviewquestions.tuteehub.com/tag/higher-1022060" style="font-weight:bold;" target="_blank" title="Click to know more about HIGHER">HIGHER</a> the temperature, greater will be thermionic <a href="https://interviewquestions.tuteehub.com/tag/emission-970172" style="font-weight:bold;" target="_blank" title="Click to know more about EMISSION">EMISSION</a>. For metals with lower work function, thermionicemission <a href="https://interviewquestions.tuteehub.com/tag/occurs-1127848" style="font-weight:bold;" target="_blank" title="Click to know more about OCCURS">OCCURS</a> at low temperature.</body></html>

Discussion

61.	Positive charge inside 2^(He) atom is…………..
Answer» <html><body><p>`1.6 xx <a href="https://interviewquestions.tuteehub.com/tag/10-261113" style="font-weight:bold;" target="_blank" title="Click to know more about 10">10</a>^(-<a href="https://interviewquestions.tuteehub.com/tag/19-280618" style="font-weight:bold;" target="_blank" title="Click to know more about 19">19</a>)` <a href="https://interviewquestions.tuteehub.com/tag/c-7168" style="font-weight:bold;" target="_blank" title="Click to know more about C">C</a><br/>`2 xx 1.6 xx 10^(-19)` C<br/>`4 xx 1.6 xx 10^(-19)` C<br/>zero coulomb </p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :<a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a></body></html>

Discussion

62.	(a) State Gauss's law for magnetism. Explain its significance. (b) Write the four important properties of the magnetic field lines due to a bar magnet.
Answer» <html><body><p></p>Solution :(a) According to Gauss. law for magnetism , "the <a href="https://interviewquestions.tuteehub.com/tag/net-5194" style="font-weight:bold;" target="_blank" title="Click to know more about NET">NET</a> magnetic flux through may closed surface is zero" i.e., <br/>`phi_B = oint vecB .""vecd s = 0` <br/> It signifies that in magnetism isolated monopoles do not exist. There are no sources/sinks of magnetic field `vecB`. The <a href="https://interviewquestions.tuteehub.com/tag/simplest-1208711" style="font-weight:bold;" target="_blank" title="Click to know more about SIMPLEST">SIMPLEST</a> magnetic element is a dipole or a current loop. <br/> (b) Four important properties of the magnetic field lines <a href="https://interviewquestions.tuteehub.com/tag/due-433472" style="font-weight:bold;" target="_blank" title="Click to know more about DUE">DUE</a> to a bar magnet are given below: <br/>(1) Magnetic field lines are a visual and intuitive realisation of the magnetic field. A magnetic field line is a smooth curve in a magnetic field, tangent to which at any point gives the direction of magnetic field at that point. <br/>(2) In free <a href="https://interviewquestions.tuteehub.com/tag/space-649515" style="font-weight:bold;" target="_blank" title="Click to know more about SPACE">SPACE</a> around a magnetic dipole the magnetic field lines start from N-pole and end at S-pole. However, inside the magnet they travel from S-pole to N-pole. Thus, magnetic field lines of a magnet or a solenoid form continuous closed curves. <br/>(3) The magnetic field lines do not intersect one another. It is so since the direction of the magnetic field would not be unique at the point of intersection. <br/> (<a href="https://interviewquestions.tuteehub.com/tag/4-311707" style="font-weight:bold;" target="_blank" title="Click to know more about 4">4</a>) The larger the number of magnetic field lines crossing per unit normal area in a given region, the stronger is the magnetic field `vecB` there.</body></html>

Discussion

63.	Ultraviolet light of wavelength 280 nm is used in an experiment on photoelectric effect with lithium ( varphi = 2.5 eV) cathode. Find (a) the maximum kinetic energy of the photoelectrons and (b) the stopping potential.
Answer» <html><body><p></p>Solution : (a) The maximum kinetic energy is <br/>` K_max = (hc/lambda)- varphi. ` <br/> `= (<a href="https://interviewquestions.tuteehub.com/tag/1242-1782646" style="font-weight:bold;" target="_blank" title="Click to know more about 1242">1242</a> eV nm/ 280 nm)- 2.5 eV. ` <br/> ` = 4.4 eV - 2.5 eV = 1.9eV. ` <br/>(<a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a>) <a href="https://interviewquestions.tuteehub.com/tag/stopping-1228133" style="font-weight:bold;" target="_blank" title="Click to know more about STOPPING">STOPPING</a> potential <a href="https://interviewquestions.tuteehub.com/tag/v-722631" style="font-weight:bold;" target="_blank" title="Click to know more about V">V</a> is given by <br/> ` eV= K_max` <br/>` or, V=(K_max)/<a href="https://interviewquestions.tuteehub.com/tag/e-444102" style="font-weight:bold;" target="_blank" title="Click to know more about E">E</a> = 1.9 eV/e = 1.9 V.`</body></html>

Discussion

64.	An alpha- particle and a photon are accelerated from rest through the same potential difference V. Find the ratio of de Broglie wavelength associated with them.
Answer» <html><body><p></p>Solution :`K.E. = ( 1)/( 2 ) m upsilon^(2) = <a href="https://interviewquestions.tuteehub.com/tag/qv-611767" style="font-weight:bold;" target="_blank" title="Click to know more about QV">QV</a>` or <br/> `upsilon= sqrt((2qV)/(m))` <br/> de Broglie <a href="https://interviewquestions.tuteehub.com/tag/wavelength-1450414" style="font-weight:bold;" target="_blank" title="Click to know more about WAVELENGTH">WAVELENGTH</a>,` <a href="https://interviewquestions.tuteehub.com/tag/lambda-539003" style="font-weight:bold;" target="_blank" title="Click to know more about LAMBDA">LAMBDA</a> = ( h )/( mv)` <br/>For same <a href="https://interviewquestions.tuteehub.com/tag/potential-1161228" style="font-weight:bold;" target="_blank" title="Click to know more about POTENTIAL">POTENTIAL</a> difference, <br/>`( lambda_(<a href="https://interviewquestions.tuteehub.com/tag/alpha-858274" style="font-weight:bold;" target="_blank" title="Click to know more about ALPHA">ALPHA</a>))/( lambda_(p))= sqrt((m_(p)q_(p))/( m_(alpha)q_(alpha)))=sqrt((m_(p)e)/( 4m_(p) 2e)) = (1)/( 2sqrt( 2))`</body></html>

Discussion

65.	Which one of the series of hydrogen spectrum is in the visible region ?
Answer» <html><body><p>Lyman series<br/>Balmer series<br/>Paschen series<br/>Bracket series</p>Solution :Balmer series of <a href="https://interviewquestions.tuteehub.com/tag/hydrogen-22331" style="font-weight:bold;" target="_blank" title="Click to know more about HYDROGEN">HYDROGEN</a> <a href="https://interviewquestions.tuteehub.com/tag/atom-887280" style="font-weight:bold;" target="_blank" title="Click to know more about ATOM">ATOM</a> <a href="https://interviewquestions.tuteehub.com/tag/lies-1073086" style="font-weight:bold;" target="_blank" title="Click to know more about LIES">LIES</a> in the <a href="https://interviewquestions.tuteehub.com/tag/visible-1447103" style="font-weight:bold;" target="_blank" title="Click to know more about VISIBLE">VISIBLE</a> <a href="https://interviewquestions.tuteehub.com/tag/region-1182095" style="font-weight:bold;" target="_blank" title="Click to know more about REGION">REGION</a> of spectrum.</body></html>

Discussion

66.	Potential energy of a bar mangnet of magnetic moment M placed in a magnetic field of induction B such that it makes an angle theta with the direction of B is (take theta =90^(@) as datum)
Answer» <html><body><p>`-M <a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a> sin theta `<br/>`-M B <a href="https://interviewquestions.tuteehub.com/tag/cos-935872" style="font-weight:bold;" target="_blank" title="Click to know more about COS">COS</a> theta`<br/>`MB (<a href="https://interviewquestions.tuteehub.com/tag/1-256655" style="font-weight:bold;" target="_blank" title="Click to know more about 1">1</a>- cos theta)`<br/>`M B (1 + cos theta)` </p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :B</body></html>

Discussion

67.	In the given circuit
Answer» <html><body><p>A is at <a href="https://interviewquestions.tuteehub.com/tag/high-479925" style="font-weight:bold;" target="_blank" title="Click to know more about HIGH">HIGH</a> <a href="https://interviewquestions.tuteehub.com/tag/potential-1161228" style="font-weight:bold;" target="_blank" title="Click to know more about POTENTIAL">POTENTIAL</a> <br/><a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a> is at high potential<br/>A and B are at the same potential<br/>A and B are at <a href="https://interviewquestions.tuteehub.com/tag/zero-751093" style="font-weight:bold;" target="_blank" title="Click to know more about ZERO">ZERO</a> potential </p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :B</body></html>

Discussion

68.	A parallel beam of monochromatic light is used in a Young's double slit experiment. The slits areseparated by a distance d and the screen is placed parallel to the plane of the slits. If the incident beam makes an angle theta = sin^(-1)((lambda)/(2d)) with the normal to the plane of the slits, there will be .....at the centre P_(0) of the pattern.
Answer» <html><body><p>1/4the <a href="https://interviewquestions.tuteehub.com/tag/maximum-556915" style="font-weight:bold;" target="_blank" title="Click to know more about MAXIMUM">MAXIMUM</a> intensity<br/>half the maximum intensity<br/>bright<br/><a href="https://interviewquestions.tuteehub.com/tag/dark-943775" style="font-weight:bold;" target="_blank" title="Click to know more about DARK">DARK</a></p>Solution :Dark <a href="https://interviewquestions.tuteehub.com/tag/fringe-1000590" style="font-weight:bold;" target="_blank" title="Click to know more about FRINGE">FRINGE</a></body></html>

Discussion

69.	If the mass of the proton were just a little closer to the mass of the neutron, the following reaction would be possible even at low collision energies : e^(-) + p to n+v Why would this situation be catastrophic ? By what percentage would the proton mass have to increased to make this reaction possible ?
Answer» <html><body><p><br/></p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :`0.083%`</body></html>

Discussion

70.	In a certain clock, a pendulum of length L_(1), has a period T_(1) = 0.95s. The length of the pendulum is adjusted is adusted to a new L_(2) such that T_(2) = 1.0s. What is the ratio L_(2)//L_(1)?
Answer» <html><body><p>`0.90`<br/>`0.95`<br/>`1.0`<br/>`1.1`</p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :D</body></html>

Discussion

71.	The capacity of a parallel plate capacitor formed by the plates of same area A is 0.02muFwith air as dielectric. Now one plate is replaced by a plate of area 2A and dielectric (k=2) is introduced between the plates, the capacity is
Answer» <html><body><p>`0.04muF`<br/>`0.08muF`<br/>`0.01muF`<br/>`<a href="https://interviewquestions.tuteehub.com/tag/2muf-1838006" style="font-weight:bold;" target="_blank" title="Click to know more about 2MUF">2MUF</a>`</p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :A</body></html>

Discussion

72.	Compare the emissivities of a caesium-coated tungsten cathode at 1000 K and that of a pure tungsten cathode at 2700 K. Assume the constant B in the Richardson-Dushmann equation to be the same for both cathodes.
Answer» <html><body><p><br/></p>Solution :The <a href="https://interviewquestions.tuteehub.com/tag/ratio-13379" style="font-weight:bold;" target="_blank" title="Click to know more about RATIO">RATIO</a> of the saturation currents of the two cathodes is <br/> `x=(i_(<a href="https://interviewquestions.tuteehub.com/tag/1-256655" style="font-weight:bold;" target="_blank" title="Click to know more about 1">1</a>))/(i_(<a href="https://interviewquestions.tuteehub.com/tag/2-283658" style="font-weight:bold;" target="_blank" title="Click to know more about 2">2</a>))=((T_(1))/(T_(2)))^(2)<a href="https://interviewquestions.tuteehub.com/tag/exp-979975" style="font-weight:bold;" target="_blank" title="Click to know more about EXP">EXP</a>((A_(2))/(kT_(2))-(A_(1))/(kT_(1)))`</body></html>

Discussion

73.	For a normal eye the least distance of distinct vision is …….. Fill in the blank.
Answer» <html><body><p><br/></p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :<a href="https://interviewquestions.tuteehub.com/tag/25-296426" style="font-weight:bold;" target="_blank" title="Click to know more about 25">25</a> <a href="https://interviewquestions.tuteehub.com/tag/cm-919986" style="font-weight:bold;" target="_blank" title="Click to know more about CM">CM</a></body></html>

Discussion

74.	…………………. signals are continuous variations of voltage or current
Answer» <html><body><p></p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :<a href="https://interviewquestions.tuteehub.com/tag/analog-873857" style="font-weight:bold;" target="_blank" title="Click to know more about ANALOG">ANALOG</a> <a href="https://interviewquestions.tuteehub.com/tag/signals-13891" style="font-weight:bold;" target="_blank" title="Click to know more about SIGNALS">SIGNALS</a>.</body></html>

Discussion

75.	In the following potentiometer circuit AB is a uniform wire of length 1 in and resistance R the potential gradient along the wire and balance length AO (= l).
Answer» <html><body><p></p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :Current flowing in the potentiometer wire <br/> `I=E/(R_"total ")=20/(<a href="https://interviewquestions.tuteehub.com/tag/15-274069" style="font-weight:bold;" target="_blank" title="Click to know more about 15">15</a>+10)=2/25A` <br/> `:.` Potential <a href="https://interviewquestions.tuteehub.com/tag/difference-951394" style="font-weight:bold;" target="_blank" title="Click to know more about DIFFERENCE">DIFFERENCE</a> across the wire `=2/25xx10=20/25=0.8A`<br/> `:.` Potential gradient `k=(V_(AB))/(I_(AB))=0.8/1.0=0.8V//m` <br/> Now, current flowing in the circuit containing experimental cell, <br/> `=15/(1.2+0.3)=1A` <br/> Potential difference across <a href="https://interviewquestions.tuteehub.com/tag/length-1071524" style="font-weight:bold;" target="_blank" title="Click to know more about LENGTH">LENGTH</a> `AO – 0.3 xx 1 = 0.3 V` <br/> Length`AO=(0.3)/(0.8)m=0.3/0xx100cm = 37.5cm `</body></html>

Discussion

76.	Which one among the following happens when a swing nses to a certain height from its rest position ?
Answer» <html><body><p>Its potential energy <a href="https://interviewquestions.tuteehub.com/tag/decreases-946143" style="font-weight:bold;" target="_blank" title="Click to know more about DECREASES">DECREASES</a> while <a href="https://interviewquestions.tuteehub.com/tag/kinetic-533291" style="font-weight:bold;" target="_blank" title="Click to know more about KINETIC">KINETIC</a> energy <a href="https://interviewquestions.tuteehub.com/tag/increases-1040626" style="font-weight:bold;" target="_blank" title="Click to know more about INCREASES">INCREASES</a><br/>Its kinetic energy decreases while potential energy increases <br/>Both potential and kinetic energy <a href="https://interviewquestions.tuteehub.com/tag/decrease-946104" style="font-weight:bold;" target="_blank" title="Click to know more about DECREASE">DECREASE</a> <br/>Both potential and kinetic energy increase </p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :b</body></html>

Discussion

77.	The shortest wavelength of X-rays, emiited from a X-ray tube, depend upon
Answer» <html><body><p><a href="https://interviewquestions.tuteehub.com/tag/current-940804" style="font-weight:bold;" target="_blank" title="Click to know more about CURRENT">CURRENT</a> in the tube<br/>voltage applied to the tube<br/>nature of glass material in the tube<br/>atomic number of the target material</p>Solution :`lambda_(<a href="https://interviewquestions.tuteehub.com/tag/min-548008" style="font-weight:bold;" target="_blank" title="Click to know more about MIN">MIN</a>) = (12375)/(V("volt")) Å, i.e., lambda_(min) <a href="https://interviewquestions.tuteehub.com/tag/infty-2738147" style="font-weight:bold;" target="_blank" title="Click to know more about INFTY">INFTY</a> (1)/(V)`</body></html>

Discussion

78.	A stationary electron placed in a magnetic field experiences a mechanical push equal to
Answer» <html><body><p>cvB<br/>zero<br/>IvB<br/>none of these</p>Answer :<a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a></body></html>

Discussion

79.	Refrigerator is an apparatus which takes heat from a cold body, work is done on it and the work done together with the heat absorbed is rejected to the source. An ideal refrigerator can be regarded as Carnot's ideal heat engine working in the reverse direction. The coefficient of performance of refrigerator is defined as beta = ("Heat extracted from cold reservoir")/("work done on working substance") = (Q_(2))/(W) = (Q_(2))/(Q_(1)- Q_(2)) = (T_(2))/(T_(1) - T_(2)) A Carnot's refrigerator takes heat from water at 0^(@)C and discards it to a room temperature at 27^(@)C . 1Kg of water at 0^(@)C is to be changed into ice at 0^(@)C. (L_(ice) = 80"kcal//kg") What is the coefficient of performance of the machine?
Answer» <html><body><p>`11.<a href="https://interviewquestions.tuteehub.com/tag/1-256655" style="font-weight:bold;" target="_blank" title="Click to know more about 1">1</a>`<br/>`10.1`<br/>`9.1`<br/>`8.1`</p>Solution :`Beta = (T_(<a href="https://interviewquestions.tuteehub.com/tag/2-283658" style="font-weight:bold;" target="_blank" title="Click to know more about 2">2</a>))/(T_(1) - T_(2)) = (273)/(<a href="https://interviewquestions.tuteehub.com/tag/27-298706" style="font-weight:bold;" target="_blank" title="Click to know more about 27">27</a>) = 10.1`</body></html>

Discussion

80.	If half the space between two concentric conducting spheres be filled with dielectric of dielectric constant k and the rest is filled with air. Show that the capacitance of the capacitor thus formed will be same as if the whole part is filled with the dielectricof dielectric constant 1/2(1+k):
Answer» <html><body><p><br/></p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :<a href="https://interviewquestions.tuteehub.com/tag/na-572417" style="font-weight:bold;" target="_blank" title="Click to know more about NA">NA</a></body></html>

Discussion

81.	Show that the force on each plate of a parallel plate capacitor has a magnitude equal to (1)/(2)QE, where Q is the charge on the capacitor and E is the magnitude of electric field between the plates. Explain the origin of the factor (1)/(2).
Answer» <html><body><p></p>Solution :Let the application of force <a href="https://interviewquestions.tuteehub.com/tag/f-455800" style="font-weight:bold;" target="_blank" title="Click to know more about F">F</a> increases the distance between the plates by `trianglex`. <br/> Work done by the external force `=Ftriangle x` <br/> This increases the energy. <br/> Energy <a href="https://interviewquestions.tuteehub.com/tag/density-17451" style="font-weight:bold;" target="_blank" title="Click to know more about DENSITY">DENSITY</a> = u <br/> So, <a href="https://interviewquestions.tuteehub.com/tag/increase-1040383" style="font-weight:bold;" target="_blank" title="Click to know more about INCREASE">INCREASE</a> in energy `= u(alpha triangle x) ""[alpha = " area of the plate "]` <br/> `:. F trianglex = u alpha "" triangle x " or, " F = u alpha` <br/> `:. F = (1)/(<a href="https://interviewquestions.tuteehub.com/tag/2-283658" style="font-weight:bold;" target="_blank" title="Click to know more about 2">2</a>)in_0 E^2* alpha ""[:. u = (1)/(2) in_0E^2]` <br/> `:. F = (1)/(2) in_0 alpha E*E = (1)/(2) <a href="https://interviewquestions.tuteehub.com/tag/qe-610319" style="font-weight:bold;" target="_blank" title="Click to know more about QE">QE</a>` <br/> The factor `(1)/(2)` arises in this relation due to the fact that average `(E )/(2) " of "0` and E is taken.</body></html>

Discussion

82.	A flint glass prism and a crown glass prism are to be combined in such a way that the deviation of the mean ray is zero. The refractive index of flint and crown glasses for the mean ray are 1620 and 1.518 respectively. If the refracting angle of the flint prism is 6.0^@, what would be the refracting angle of the crown prism ?
Answer» <html><body><p><br/></p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :Given that <br/> Refractive index of flint glass `=mu_f=1.620` <br/> Refractive index of crown glass `=m_e=1.518` <br/> Refractive <a href="https://interviewquestions.tuteehub.com/tag/angle-875388" style="font-weight:bold;" target="_blank" title="Click to know more about ANGLE">ANGLE</a> of flint proms =`A_f=6^@` <br/> for <a href="https://interviewquestions.tuteehub.com/tag/zero-751093" style="font-weight:bold;" target="_blank" title="Click to know more about ZERO">ZERO</a> net deviation of mean by <br/> `(mu_1-1)A_f=(mu_e-1)A_c` <br/> `rarr A_c=(mu_f-1)/(mu_c-1)` <br/> `A_f=(1.620-1)/(1.518-1)(6.0)^@=7.2^0`</body></html>

Discussion

83.	If the degrees of freedom of a gas are f, then the ratio of its specific heats (C_(p))/(C_(v)) is given by :
Answer» <html><body><p><<a href="https://interviewquestions.tuteehub.com/tag/p-588962" style="font-weight:bold;" target="_blank" title="Click to know more about P">P</a>>`1-(2)/(f)`<br/>`1+(2)/(f)`<br/>`1+(1)/(f)`<br/>`1-(1)/(f)`</p>Solution :`C_(v)=f cdot (1)/(2) <a href="https://interviewquestions.tuteehub.com/tag/r-611811" style="font-weight:bold;" target="_blank" title="Click to know more about R">R</a>` <br/> `C_(P) =C_(v)+R =(1)/(2) f R+R =((f)/(2)+1)R` <br/> `therefore gamma =(C_(P))/(C_(v))=((f)/(2)+1)(R)/((f)/(2) cdot R)=1+(2)/(f)` <br/> Thus, <a href="https://interviewquestions.tuteehub.com/tag/correct-409949" style="font-weight:bold;" target="_blank" title="Click to know more about CORRECT">CORRECT</a> choice is (b).</body></html>

Discussion

84.	A cubical block rests on a plane rough surface with coefficient of static friction (1)/(sqrt(3)). AT what angle the plane be inclined so that the block just slides?
Answer» <html><body><p>`<a href="https://interviewquestions.tuteehub.com/tag/60-328817" style="font-weight:bold;" target="_blank" title="Click to know more about 60">60</a>^(@)` <br/>`<a href="https://interviewquestions.tuteehub.com/tag/20-287209" style="font-weight:bold;" target="_blank" title="Click to know more about 20">20</a>^(@)` <br/>`30^(@)` <br/>`<a href="https://interviewquestions.tuteehub.com/tag/15-274069" style="font-weight:bold;" target="_blank" title="Click to know more about 15">15</a>^(@)` </p>Answer :<a href="https://interviewquestions.tuteehub.com/tag/c-7168" style="font-weight:bold;" target="_blank" title="Click to know more about C">C</a></body></html>

Discussion

85.	What is the forbidden energy gap (in joule) for a Germanium crystal ?
Answer» <html><body><p>`1.6xx10^-19J`<br/>`1.12xx10^-19J`<br/>`3.2xx10^-19J`<br/>`2.24xx10^-19J`</p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :<a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a></body></html>

Discussion

86.	A charged particle is moving with velocity vecv in a uniform magnetic field vecB. The magnetic force acting on it will be maximum when _____ .
Answer» <html><body><p>`vecvandvecB` are in same direction.<br/>`vecvandvecB` are in opposite direction.<br/>`vecvandvecB` are <a href="https://interviewquestions.tuteehub.com/tag/mutually-7377074" style="font-weight:bold;" target="_blank" title="Click to know more about MUTUALLY">MUTUALLY</a> <a href="https://interviewquestions.tuteehub.com/tag/perpendicular-598789" style="font-weight:bold;" target="_blank" title="Click to know more about PERPENDICULAR">PERPENDICULAR</a>. <br/>`vecvandvecB` <a href="https://interviewquestions.tuteehub.com/tag/make-546668" style="font-weight:bold;" target="_blank" title="Click to know more about MAKE">MAKE</a> an angle of `45^(@)` with each other.</p>Solution :Magnetic force on <a href="https://interviewquestions.tuteehub.com/tag/charged-7263949" style="font-weight:bold;" target="_blank" title="Click to know more about CHARGED">CHARGED</a> particle, <br/> `vecF=q(vecvxxvecB)` <br/> `thereforeF=qvBsintheta` <br/> Where angle between `vecvandvecB` is `<a href="https://interviewquestions.tuteehub.com/tag/theta-1412757" style="font-weight:bold;" target="_blank" title="Click to know more about THETA">THETA</a>`. <br/> When `vecv_\|_vecB`, then `theta=90^(@)` <br/> `thereforeF=qvBsin90^(@)` <br/> `thereforeF=qvB` is maximum force.</body></html>

Discussion

87.	The displacement of a particle is given by x = (t - 2)^(2) where x is in meters and t in seconds. The distance covered by the particle in first 4 seconds is
Answer» <html><body><p><a href="https://interviewquestions.tuteehub.com/tag/4-311707" style="font-weight:bold;" target="_blank" title="Click to know more about 4">4</a> m<br/> <a href="https://interviewquestions.tuteehub.com/tag/8-336412" style="font-weight:bold;" target="_blank" title="Click to know more about 8">8</a> m <br/>12 m <br/><a href="https://interviewquestions.tuteehub.com/tag/16-276476" style="font-weight:bold;" target="_blank" title="Click to know more about 16">16</a> m </p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :<a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a></body></html>

Discussion

88.	Assertion : Phase difference between two points separated by a distance equal to lambda//2 on same wavefront is pi. Reason : Path difference (Delta x) and phase difference (delta) are related as delta = (2 pi)/(lambda) Delta x.
Answer» <html><body><p>If both assertion and <a href="https://interviewquestions.tuteehub.com/tag/reason-620214" style="font-weight:bold;" target="_blank" title="Click to know more about REASON">REASON</a> are <a href="https://interviewquestions.tuteehub.com/tag/correct-409949" style="font-weight:bold;" target="_blank" title="Click to know more about CORRECT">CORRECT</a> and reason is a correct <a href="https://interviewquestions.tuteehub.com/tag/explanation-455162" style="font-weight:bold;" target="_blank" title="Click to know more about EXPLANATION">EXPLANATION</a> of the assertion.<br/>If both assertion and reason and correct but reason is not the correct explanation of assertion.<br/>If assertion is correct but reason is <a href="https://interviewquestions.tuteehub.com/tag/incorrect-499101" style="font-weight:bold;" target="_blank" title="Click to know more about INCORRECT">INCORRECT</a>.<br/>If assertion is incorrect but reason is correct. </p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :D</body></html>

Discussion

89.	Two wires A and B are of lengths 40 cm and 30 cm. A is bent into a circle of radius r and B into an arc of radius r. A current i, is passed through A and i, through B. To have the same magnetic induction at the centre, the ratio of i_1:i_2 is
Answer» <html><body><p>`<a href="https://interviewquestions.tuteehub.com/tag/3-301577" style="font-weight:bold;" target="_blank" title="Click to know more about 3">3</a>:4`<br/>`3 :<a href="https://interviewquestions.tuteehub.com/tag/5-319454" style="font-weight:bold;" target="_blank" title="Click to know more about 5">5</a>`<br/>`2:3`<br/>`4:3`</p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :A</body></html>

Discussion

90.	100 gm of ice at 0^@c is mixed with 100gm of water at 100^@C . What will be the final temperature of the mixture
Answer» <html><body><p>a)`10^@<a href="https://interviewquestions.tuteehub.com/tag/c-7168" style="font-weight:bold;" target="_blank" title="Click to know more about C">C</a>`<br/><a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a>)`20^@C`<br/>c)`30^@C`<br/>d)`<a href="https://interviewquestions.tuteehub.com/tag/40-314386" style="font-weight:bold;" target="_blank" title="Click to know more about 40">40</a>^@C`</p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :A</body></html>

Discussion

91.	Which of the following is the unit of magnetic induction ?
Answer» <html><body><p>T<br/>`Wb//m^2` <br/>`N//Am`<br/>all of these </p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :D</body></html>

Discussion

92.	An audio signal is modulated by a carrier wave of 20 MHz such that the bandwidth required for modulation is 3KHz. Could this wave be demodulated by a diode detector which has the values of R and C as
Answer» <html><body><p>`R=1kOmega,<a href="https://interviewquestions.tuteehub.com/tag/c-7168" style="font-weight:bold;" target="_blank" title="Click to know more about C">C</a>=0.01muE`<br/>`R=10kOmega,C=0.01muF`<br/>`R=10kOmega,C=0.1pF`<br/>None of these </p>Solution : `v_(c)=20MHz=20xx10^(6)Hz` <br/> `(1)/(v_(c))=(1)/(20)xx10^(-6)=0.05xx10^(-6)=0.5xx10^(-7)s` <br/> Band width =`20_(m)=3kHz=3xx10^(<a href="https://interviewquestions.tuteehub.com/tag/3-301577" style="font-weight:bold;" target="_blank" title="Click to know more about 3">3</a>)Hz` <br/> `v_(m)=1.5xx10^(3)Hz` <br/> `(1)/(v_(m))=(1)/(1.<a href="https://interviewquestions.tuteehub.com/tag/5-319454" style="font-weight:bold;" target="_blank" title="Click to know more about 5">5</a>)xx10^(-3)=0.7xx10^(-3)s`. <br/> Diode detector can demodulate when <br/> `(1)/(v_(c))ltltRCltlt(1)/(v_(m))` <br/> (i)RC=`1kOmegaxx0.01muF=10^(3)<a href="https://interviewquestions.tuteehub.com/tag/xx-747671" style="font-weight:bold;" target="_blank" title="Click to know more about XX">XX</a>(0.01xx10^(-6))=10^(-5)s`. it can be demodulated. <br/> (ii) RC=`10kOmegaxx1xx10^(-8)=10^(-<a href="https://interviewquestions.tuteehub.com/tag/4-311707" style="font-weight:bold;" target="_blank" title="Click to know more about 4">4</a>)s`It can be demodulated <br/> (iii) RC`=10kOmegaxx1pF=10^(4)xx10^(-12)=10^(-8)s` <br/> It cannot be demodulated.</body></html>

Discussion

93.	State the working of a.c. generator with the help of a labelled diagram.The coil of an a.c. generator having N turns, each of area A, is rotated with a constant angular velocity omega. Deduce the expression for the alternating e.m.f. generated in the coil. What is the source of energy generation in this device?
Answer» <html><body><p></p>Solution :A.<a href="https://interviewquestions.tuteehub.com/tag/c-7168" style="font-weight:bold;" target="_blank" title="Click to know more about C">C</a>. Generator: See Q.30 (or) 2008, O.D. Set-1 <br/><br/> The <a href="https://interviewquestions.tuteehub.com/tag/essential-975317" style="font-weight:bold;" target="_blank" title="Click to know more about ESSENTIAL">ESSENTIAL</a> parts of an a.c. generator are shown in the figure. Initially the armaturecoil ABCD is horizontal. As the coil is rotasted clockwise , the arm AB moves up and CD moves down. By Flemming's right hand rule, the induced current flows along ABCD, In second half rotation, the arm CD moves up and AB moves down. The induced current flows in the opposite direction i.e. along DCBA. Thus an alternating current flows in the <a href="https://interviewquestions.tuteehub.com/tag/circuit-916593" style="font-weight:bold;" target="_blank" title="Click to know more about CIRCUIT">CIRCUIT</a> <br/> The magnetic flux linked with the coil at any instant is <br/> `""phi="NA A "cos omegat` <br/> `"Induced emf will be" ""E=-(dphi)/(dt)=-(d)/(dt)("NBA cos "omegat)=NBA omega sin omegat` <br/> `or ""E=E_(0) sin omegat` <br/> Where, `E_(0)=NBA omega`= peak value of induced emf. <br/> (b) To calculate the magnitude of e.m.f induced <br/> Suppose <br/> N=number of turns in the coil. <br/> A=area of enclosed by each turn of coil. <br/> `overset(rightarrow)B`=strength of magnetic field. <br/> `theta=` <a href="https://interviewquestions.tuteehub.com/tag/angle-875388" style="font-weight:bold;" target="_blank" title="Click to know more about ANGLE">ANGLE</a> which <a href="https://interviewquestions.tuteehub.com/tag/normal-1123860" style="font-weight:bold;" target="_blank" title="Click to know more about NORMAL">NORMAL</a> to the coil makes with `overset(rightarrow)B` at any instant t, <br/> <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/SB_PHY_XII_11_OD_E01_032_S01.png" width="80%"/> <br/> `therefore` Magnetic flux linked with the coil in this position. <br/> `""phi=N(overset(rightarrow)B.overset(rightarrow)A)` <br/> `""=NBA cos theta` <br/> `""=NBA cos omega"".....(i)` <br/> Where `omega` be the angular velocity of the coil. At this instant t, if e in the e.m.f induced in the coil, then `e=(-dphi)/(dt)=(-d)/(dt)(NAB cos omegat)=-NAB (d)/(dt)(cos omegat)` <br/> `""=-NAB(-sin omegat)omega` <br/> `""e=NAB" "omega sin omegat......(ii)` <br/> The induced, e.m.f. will be maximum, when <br/> `""sin omegat="maximum "=1` <br/> `therefore""e_("max")=e_(v)=NAB_(omega)xx1.......(iii)` <br/> Put in (ii)`""e=e_(0) sin omegat` <br/> (c ) Mechanical energy is converted into electrical energy. '</body></html>

Discussion

94.	The range of ammeter can be………………………but can not be……………….. .
Answer» <html><body><p><br/></p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :<a href="https://interviewquestions.tuteehub.com/tag/increased-1040402" style="font-weight:bold;" target="_blank" title="Click to know more about INCREASED">INCREASED</a> ; <a href="https://interviewquestions.tuteehub.com/tag/decreased-7266469" style="font-weight:bold;" target="_blank" title="Click to know more about DECREASED">DECREASED</a></body></html>

Discussion

95.	Light of wavelength 5900 xx 10^(-10)m falls normally on a slit of width 11.8 xx 10^(-7)m. The resulting diffraction pattern is received on a screen. The angular position of the first minimum is.
Answer» <html><body><p>`<a href="https://interviewquestions.tuteehub.com/tag/30-304807" style="font-weight:bold;" target="_blank" title="Click to know more about 30">30</a>^(@)`<br/>`<a href="https://interviewquestions.tuteehub.com/tag/60-328817" style="font-weight:bold;" target="_blank" title="Click to know more about 60">60</a>^(@)`<br/>`<a href="https://interviewquestions.tuteehub.com/tag/45-316951" style="font-weight:bold;" target="_blank" title="Click to know more about 45">45</a>^(@)`<br/>`<a href="https://interviewquestions.tuteehub.com/tag/90-341351" style="font-weight:bold;" target="_blank" title="Click to know more about 90">90</a>^(@)`</p><a href="https://interviewquestions.tuteehub.com/tag/answer-15557" style="font-weight:bold;" target="_blank" title="Click to know more about ANSWER">ANSWER</a> :A</body></html>

Discussion

96.	The thermal radiations are similar to :
Answer» <html><body><p>X-rays<br/>cathode rays <br/>`alpha-` rays <br/><a href="https://interviewquestions.tuteehub.com/tag/sound-648690" style="font-weight:bold;" target="_blank" title="Click to know more about SOUND">SOUND</a> waves. </p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :<a href="https://interviewquestions.tuteehub.com/tag/thermal-706916" style="font-weight:bold;" target="_blank" title="Click to know more about THERMAL">THERMAL</a> radiations are e.m. waves as are X-rays. <br/> <a href="https://interviewquestions.tuteehub.com/tag/thus-2307358" style="font-weight:bold;" target="_blank" title="Click to know more about THUS">THUS</a> correct <a href="https://interviewquestions.tuteehub.com/tag/choice-915996" style="font-weight:bold;" target="_blank" title="Click to know more about CHOICE">CHOICE</a> is (a).</body></html>

Discussion

97.	Number of turns in the primary coil and the secondary coil of an ideal transformer are 500 and 2500 respectively. If current in the secondary coil is 0.2 A, calculate current in the primary coil. Also calculate transformer ratio. If voltage in the secondary coil is 750 V, calculate voltage in the primary coil.
Answer» <html><body><p><a href="https://interviewquestions.tuteehub.com/tag/150-275254" style="font-weight:bold;" target="_blank" title="Click to know more about 150">150</a> V<br/>160 V<br/>170 V<br/>140 V</p>Solution :Here,`N_1` =500 , `N_2`= 2500 <br/> `I_1`=? , `I_2`= 0.2 A <br/> `V_1`= ? , `V_2`= 750 V <br/> Transformation ratio `r=N_2/N_1` <br/> `=2500/500` <br/>`<a href="https://interviewquestions.tuteehub.com/tag/therefore-706901" style="font-weight:bold;" target="_blank" title="Click to know more about THEREFORE">THEREFORE</a>` r=<a href="https://interviewquestions.tuteehub.com/tag/5-319454" style="font-weight:bold;" target="_blank" title="Click to know more about 5">5</a> <br/> For current in <a href="https://interviewquestions.tuteehub.com/tag/primary-1165403" style="font-weight:bold;" target="_blank" title="Click to know more about PRIMARY">PRIMARY</a> coil, <br/>`N_1/N_2=I_2/I_1` <br/>`therefore I_1=I_2 xx N_2/N_1` <br/> = 0.2 x 5 =1.0 A <br/> For voltage in primary coil, <br/> `N_2/N_1=V_2/V_1` <br/>`therefore V_1=V_2 xx N_1/N_2` <br/>`= 750xx500/2500` <br/>`therefore V_1`= 150 V</body></html>

Discussion

98.	Find the greatest possible angle through which a deuteron is scattered as result of elastic collision with an initially stationary proton ? Take m_(1) & m_(2) as masses of a proton & a deuterium.
Answer» <html><body><p><br/></p>Answer :`[beta_(max) = <a href="https://interviewquestions.tuteehub.com/tag/sin-1208945" style="font-weight:bold;" target="_blank" title="Click to know more about SIN">SIN</a>^(-1).(m_(1))/(m_(<a href="https://interviewquestions.tuteehub.com/tag/2-283658" style="font-weight:bold;" target="_blank" title="Click to know more about 2">2</a>)) = 30^(@)]`</body></html>

Discussion

99.	The figure shows the graphical variation of the rectance of a capacitor with frequency of acsource. (a) Find the capacitance of the capacitor. (b) An ideal inductor has the same reactance at 100 Hz frequency as the capacitor has at the same frequency. Find the value of inductance of the inductor. (c ) Draw the graph showing the variation of the rectance of this inductor with frequency.
Answer» <html><body><p></p><a href="https://interviewquestions.tuteehub.com/tag/solution-25781" style="font-weight:bold;" target="_blank" title="Click to know more about SOLUTION">SOLUTION</a> :(a) As per graph for a frequency v = 100 Hz the capacitive reactance `X_(<a href="https://interviewquestions.tuteehub.com/tag/c-7168" style="font-weight:bold;" target="_blank" title="Click to know more about C">C</a> )=6Omega`. <br/> `because X_(C )=(1)/(C omega)=(1)/(C.2pi v)` <br/> `<a href="https://interviewquestions.tuteehub.com/tag/rarr-1175461" style="font-weight:bold;" target="_blank" title="Click to know more about RARR">RARR</a> C=(1)/(2pi v. X_(C ))=(1)/(2xx3.14xx100xx6)=2.65xx10^(-4)F or 265 muF` <br/> (b) As for v = 100 Hz, <br/> `X_(L)=X_(C )=6Omega` <br/> `rArr L.2pi xx 100=<a href="https://interviewquestions.tuteehub.com/tag/6-327005" style="font-weight:bold;" target="_blank" title="Click to know more about 6">6</a> rArr L=(6)/(2pi xx 100)=9.55xx10^(-3)H or 9.55 <a href="https://interviewquestions.tuteehub.com/tag/mh-1082136" style="font-weight:bold;" target="_blank" title="Click to know more about MH">MH</a>` <br/> (c )`X_(L)-v` graph is shown here: <br/> <img src="https://doubtnut-static.s.llnwi.net/static/physics_images/U_LIK_SP_PHY_XII_EP_20_02_E01_028_S01.png" width="80%"/></body></html>

Discussion

100.	Transistor input characteristics curves are the graphs drawn with
Answer» <html><body><p>Collector current `I_C` on y-axis and the collector <a href="https://interviewquestions.tuteehub.com/tag/emitter-970223" style="font-weight:bold;" target="_blank" title="Click to know more about EMITTER">EMITTER</a> voltage `V_(CE)` on X-axis for a <a href="https://interviewquestions.tuteehub.com/tag/constant-930172" style="font-weight:bold;" target="_blank" title="Click to know more about CONSTANT">CONSTANT</a> base current<br/>Base current `I_B ` on y-axis and the base-emitter voltage `V_(BE)` on X-axis for a constant collector emitter voltage<br/>Base current `I_B` on y-axis and the collector emitter voltage `(V_(<a href="https://interviewquestions.tuteehub.com/tag/cb-406981" style="font-weight:bold;" target="_blank" title="Click to know more about CB">CB</a>))` on x-axis for a constant collector current <br/>Base current `I_B ` on y-axis and collector current `I_C` on x-axis with constant base emitter voltage </p>Answer :<a href="https://interviewquestions.tuteehub.com/tag/b-387190" style="font-weight:bold;" target="_blank" title="Click to know more about B">B</a></body></html>

Discussion

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