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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 7951. |
Deviation of the ray after reflection is given by ____ where I is angle of incidence. |
| Answer» SOLUTION :`PI- 2I` | |
| 7952. |
When we shunt a galvanometer with a resistance of 20Omega its deflection is reduced of 20Omegaits deflection is reduced to half. What is the resistance of the galvanometer ? |
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Answer» `80 OMEGA` |
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| 7953. |
Frequency of revolution of an electron in Bohr's orbit of hydrogen atom is proportional to: |
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Answer» `1/n` |
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| 7954. |
The earth (mass =6xx10^(4)kg) revolves around the sun with an angular velocity of 2xx10^(-2) rad/s in a circular orbit of radius 1.5xx10^(8) km. The force excerted by the sun on the earth in newton, is |
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Answer» `36xx10^(21)` Angular velocity`(omega)=2XX10^(-7)" rad"//s` and radius(R )`=1.5xx10^(8)" km"=1.5xx10^(11)" m"`. FORCE exerted on the EARTH`=mRomega^(2)` `=(6xx10^(24))xx(1.5xx10^(11))xx(2xx10^(-7))^(2)=36xx10^(21)N` |
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| 7955. |
Sketch the energy level diagram for hydrogen atom and mark the transitions for different spectral series of hydrogen. |
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Answer» Solution :The energy level diagram showing ground state as well as first few excited STATES for hydrogen atom has been shown in Fig. 12.09. TRANSITIONS for different SPECTRAL series of hydrogen have been shown by straight LINES with arrow HEAD marks. 
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| 7956. |
We cannot use a D.C. Voltmeter to measure an alternating voltage because, |
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Answer» the alternating voltage changes direction |
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| 7957. |
A smooth wedge of mass m and angle of inclination 60^(@)rests unattached between two springs of spring constant K and 4k on a smooth horizontal plane both springs in the unextended position the time period of small oscillation of the wedge (assuming that the springs are constrained to get compressed along their length) equals |
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Answer» `pi(1+1/2)SQRT(m/k)`  `F=4kx cos^(2)30^(@) Rightarrow VEC(a) =-((k3)/M^(4))xx4vec(x) Rightarrow infty^(2)=(3k)/M infty=sqrt((3k)/M)` `Rightarrow T=(2pi)/infty=(2pi)/sqrt(3k//M) Rightarrow T=(2pi)/sqrt(3k)sqrt(M) Rightarrowt_(1)=T_(1)/2=pi/sqrt(3k) sqrt(M)` `Rightarrow t_(2)=T_(2)/2=pisqrt(M/k)` Rightarrow time period `= t_(1)+ t_(2) = [(pisqrt(M))/sqrt(3k)+pi sqrt(M/k)]` `Rightarrow time period= t_(1)+t_(2)= pisqrt(m/k)[1+1/sqrt(3)]` ANS |
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| 7958. |
If V_(0) be the potential at origin in an electric field (Q)/(piepsilon_(0)R) the potential at (x,y) is |
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Answer» `V_(0)-xE_(x)-yE_(y)` |
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| 7959. |
Magnetic field in a region is given by B=B_0+hatk. Two loops each of side a is placed in the magnetic region in the xy-plane with one of its sides on x-axis. If F_1 is the force on loop 1 and dF_2 be the force on loop 2, then |
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Answer» `F_1=F_2=0` Forces on two wires parallel to y-axis can be obtaine ddirectly (without integration) as value of `B` is same along these wires. But theri values will be different (as x-coordinate and therefore `B` is diferent). `F_(NET)=/_\F` (on two wires) `=Ia(/_\B)=Ia(B_0)(/_\x)` `=IaB_0(a)=IB_0a^2` this is indecent of x `:. F_1=F_2=IBla^2=0` |
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| 7960. |
Which of the following Maxwell's equations have sources of vecE and vecB? |
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Answer» `oint_SvecE. VEC(ds)=Q/(in_0)` electric field and equation (b) is related with source of MAGNETIC field. |
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| 7961. |
Derive the expression for power P=Vi in electrical circuit. |
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Answer» <P> Solution :The electrical power P is the RATE at which the electrical POTENTIAL energy is DELIVERED,`P=(DU)/(dt)=(d)/(dt)(V.dQ)=V(dQ)/(dt)` Since the electric current `I=(dQ)/(dt)` So the equation can be rewritten as `P=VI`. |
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| 7962. |
State and prove Brewster's law of polari- zation. |
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Answer» Solution :Statement of Brewster.s LAW It STATES the tangent of polarising angle is equal to the REFRACTIVE index of the material i.e. `tan i_(p)=mu` It is found that when light is incident in a transparent medium at polarising angle, the reflected and refracted rays are perpendicular to each other. Malus found that an ordinary beam, on refracted from transparent medium, becomes partially polarised. The degree of polarisation increases as the angle of incidence is increased. At a particular angle of incidence, called as the polarising angle, the reflected beam becomes completely polarised.  AB is the incident ray and BC is the reflected ray at the polarising angle `i = i_(p)`. The reflected ray BC is plane polarised with its vibrations perpendicular to plane of the PAPER. A part of the light is refracted along BD. It is found that both the reflected ray and the refracted ray are perpendicular to each other i.e. `/_CBD=90^(@)` `:. i_(p)+r=90^(@)` or `r=90^(@)-i_(p)` According to Snell.s law. `mu=(SIN i)/(sin r)=(sin i_(p))/(sin(90^(@)-i_(p))` `=(sin i_(p))/(cos i_(p))=tan i_(p)` Thus, the refractive index pf transparent medium is equal to tangent of polarising angle. Given `i_(p)=60^(@)` `:. mu-tan60^(@)=sqrt3` |
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| 7963. |
यदि y=x^3+4x^2+5 तो x=0 पर (d^2y)/(dx^2) का मान निकाले ? |
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Answer» 5 |
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| 7964. |
An alternating voltage given as V=200sqrt2sin (100t)V is applied to a capacitor of 1 muf. The current reading of the ammeter will be equal to ...... mA. |
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Answer» 100 but `|Z|=1/(omegaC)=1/(100xx10^(-6))=1/10^(-4)` Now `I_(RMS)=I_m/sqrt2 =V_m/(sqrt2|Z|)=(200sqrt2)/(sqrt2xx1/(10^(-4)))` `=200xx10^(-4) =20xx10^(-3)` Amp = 20 mA |
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| 7965. |
A body of mass 5 kg is thrown vertically up with a kinetic energy of 490 J.The height at which the kinetic energy of the body becomes half of the origibnal value is |
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Answer» 5 m `mgh=1/2xx490=245J` `H=(2450)/(5xx9.8)=5M` |
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| 7966. |
When n - p - n transistor is used as an amplifier , then : |
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Answer» <P>ELECTRONS MOVE from base to collector |
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| 7967. |
An electron moves along the line AB , which lies in the same plane as a circular loop of conducting wires as shown in the diagram. What will be the direction of current induced if any, in the loop |
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Answer» No current will be INDUCED |
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| 7968. |
Why cannot we use Si and Ge in fabrication of visible LEDs ? |
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Answer» |
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| 7969. |
In a p-n junction diode, change in the temperature due to heating ……. |
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Answer» AFFECT the OVERALL V-I characteristics of p-n JUNCTION. |
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| 7970. |
A double convex lens made of glass (mu = 1.5 ) has both radii of curvature of magnitude 20 cm. Incident rays parallel to the axis of the lens will converge at a distance L from the lens such that : |
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Answer» L = 10 cm |
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| 7971. |
A diffraction has 5000 lines per cm. What is its grating element ? |
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Answer» |
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| 7972. |
A boy 1.5 m tall with his eye level at 1.38 m stands before a mirror fixed on a wall. The minimum length of mirror required to view the complete image of boy is |
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Answer» 0.75 m |
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| 7973. |
Two long straight conductors carrying current I are located at the corners A and B of an equilateral triangle ABC of side 2a and they are perpendicular to the plane of the triangle. Calcualte the force on a conductor carrying the same current and placed along the median CD and equal to it in length. |
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| 7974. |
A piece of burnt wood of mass 20 g is found to have a .^(14)C activity of 4 decay s^(-1) . How long has the tree that this wood belonged to be dead ? Given T_((1)/(2)) of .^(14)C= 5730 year. |
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Answer» 1840 |
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| 7975. |
In the nuclear reaction , ""_(1) H^(2) + ""_(1) H^(3) = ""_(2) He^(4) + X ,, the emitted particle X is |
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Answer» NITROGEN of MASS 16 |
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| 7976. |
Two bodies are projected from the same point of a plane with the same speeds and at different angles of projection so that they both strike the same point on a plane which is inclined at an angle of 30^(@) with the horizontal. If first body was projected at an angle of 45^(@) with the horizontal, then find out the ratio of their times of flight. |
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Answer» |
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| 7977. |
Wave front is the locus of all points, where the particles of the medium vibrate with the same |
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Answer» PHASE |
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| 7978. |
Binding energies of H^(2), ""_(2)He^(4), ""_(26)Fe^(56) and ""_(92)U^(235)nuclei are 2.22Mev,28.4Mev, 492Mev and 1786MeV respectively which one of the following is more stable? |
| Answer» Answer :C | |
| 7979. |
One mole of radium has an activity of 1/3.7 kilo curie. Its decay constant will be |
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Answer» `1/6xx10^(-10) s^(-1)` |
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| 7980. |
A particle is moving in a circular path of radius r under the action of a force F. If at an instant velocity of particle is v,and speed of particle is increasing, then |
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Answer» `vecF.vecv=0` |
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| 7981. |
A positron has the same mass as : |
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Answer» PROTON |
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| 7982. |
Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity (angular deflection per unit voltage applied) is 20 div/V. The resistance of the galvanometer is |
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Answer» `500Omega` but `theta/V=(NAB)/(KR)""(becausetheta/I=(NAB)/K)` `thereforetheta/V=theta/(IR)" "therefore5000xx1/20=250" "thereforeR=250Omega` |
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| 7983. |
An electron beais moving horizontally towards east. If this beam passes through a uniform magnetic field directed upwards, then in which direction will the beam be deflected? |
| Answer» SOLUTION :TOWARDS NORTH | |
| 7984. |
Read the passage given below and then answer questions on the basis of your under standing of the passage and the related studied concepts. Passage: When a resistor is connected across the terminals of a battery, a current is established in the circuit which has a unique direction going from positive terminal to the negative terminal via the external resistor. Magnitude of the current also remains practically constant. If the direction of the current in a resistor (or any other element) changes alternately, the current is called an alternating current. The alternating current being supplied in our houses varies sinusoidally with time. Such a current repeats its value after a finite time interval T, called the time period. So, the current is positive for one half period and is negative for the remaining half period. In reality it means that direction of current reverses after every half time period. An alternating current may be expressed asI = I_(w) sin (omega t + phi) where I_(m)is the peak value of current or the current amplitude. The mean current for a period T is definitely zero but mean of I^(2) over the same period is not zero because I^(2)is always positve. The average of l^(2)over a time period T or a long period of time isl_(m)^(2) = l_(m)^(2)/2 . The square root of mean square current is called rms current or virtual current and it is given asI_(rms) = I_(m)/sqrt(2) (e) Show that mean value of an a.c. expressed as I = I_(m) sin omega t for one complete cycle is zero. |
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Answer» Solution :If `I= I_(m) sin omega t`, then `I_("mean") = (int_(0)^(T) I DT)/(int_(0)^(T)dt) = 1/T int_(0)^(T) I_(m) sin OMEGAT dt = 1/T [(I_(m) cos omega t)/(omega)]_(0)^(T) =(-I_(m))/(omega T) [(cos omega T - cos 0^(@))]` `=-1/(2pi) [+1 -1]=0` |
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| 7985. |
Calculate the specific heat of a metal from the following data. A container made of the metal has a mass of 3.6 kg and contains 15 kg of water. A 1.8 kg piece of the metal initially at a temperature of 180^@ C is dropped into the water. The container and water initially have a temperature of 16.0^@ C, and the final temperature of the entire (insulated) system is 18.0^@ C. |
| Answer» SOLUTION :0.44 KJ /KG K | |
| 7986. |
Lysosomes arises from- |
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Answer» ENDOPLASMIC reticulum |
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| 7987. |
Read the passage given below and then answer questions on the basis of your under standing of the passage and the related studied concepts. Passage: When a resistor is connected across the terminals of a battery, a current is established in the circuit which has a unique direction going from positive terminal to the negative terminal via the external resistor. Magnitude of the current also remains practically constant. If the direction of the current in a resistor (or any other element) changes alternately, the current is called an alternating current. The alternating current being supplied in our houses varies sinusoidally with time. Such a current repeats its value after a finite time interval T, called the time period. So, the current is positive for one half period and is negative for the remaining half period. In reality it means that direction of current reverses after every half time period. An alternating current may be expressed asI = I_(w) sin (omega t + phi) where I_(m)is the peak value of current or the current amplitude. The mean current for a period T is definitely zero but mean of I^(2) over the same period is not zero because I^(2)is always positve. The average of l^(2)over a time period T or a long period of time isl_(m)^(2) = l_(m)^(2)/2 . The square root of mean square current is called rms current or virtual current and it is given asI_(rms) = I_(m)/sqrt(2) (d) What is the peak value of voltage supplied in our houses ? |
| Answer» SOLUTION :Peak value of voltage `V_(m) = 220 xx sqrt(2) V = 331 V`. | |
| 7989. |
Consider a transparent hemisphere (n=2) in front of which a small object is placed in air (n=1) as shown. Consider a ray starting from O which strikes the spherical surface at grazing incidence (i=90^(@)) Taking x=R what will be the angle (from the normal) at which the ray emerges from the plane surface. |
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Answer» `90^(@)` Taking refraction first at curve surface `2/v_(1)+1/x=1/R Rightarrow v_(1)=(2Rx)/(x-R)` for PLANE surface `v'=v_(1)-R Rightarrowv'=(xR+R^(2))/(x-R)Rightarrow1/v-(2(x-R))/(R(x+R))=0` `1/v=(2(x-R))/(R(x+R))` for virtual image `1/vlt0 Rightarrow(2(x-R))/(R(x+R))lt0` `xltR` (2)For`x=2R` `v_(1)=(4R^(2))/R=4R Rightarrow u=-2R` `m_(1)=mu_(1)/mu_(2).v/u=1/2. (4R)/((-2R))=-1` `m_(2)=1 Rightarrow m_(1)m_(2)=-1` Image is REAL inverted and same size. 
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| 7990. |
For the past some time, Aarti had been observing some erratic body movement, unsteadiness and lack of Radha, who also used to complain of sever headache occasionally. Aarti suggested to herparents to get a medical check-up of Radha. The doctor thoroughly examined Radha and diagnosed that she has a brain tumour. What, according to you, are the values displayed by Aarti? How can radioisotepes help a doctor to diagnose brain tumour? |
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Answer» Solution :(a) Aarti has displayed awareness and care towards the health of her sister. (B) During the intake ofdifferent elements and compounds, the biological organisms absorb them differently. Also, the EXACT distribution of the elements and their function in the various parts of organisms cannot be KNOWN clearly. For this, a radioisotope is made ot enter the organism along with the elements and compounds, whose absorption, functioning and distribution to the brain has to be studied. The radioisotope act as a tag of label for the elements or COMPOUND under study. BY detecting the radiation emitted by the isotope from the brain, the regarding the absorption and function of the compounds by the organisms, are found out. In this way, radioisotope help a doctor to diagnose brain TUMOUR. |
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| 7991. |
Read the passage given below and then answer questions on the basis of your under standing of the passage and the related studied concepts. Passage: When a resistor is connected across the terminals of a battery, a current is established in the circuit which has a unique direction going from positive terminal to the negative terminal via the external resistor. Magnitude of the current also remains practically constant. If the direction of the current in a resistor (or any other element) changes alternately, the current is called an alternating current. The alternating current being supplied in our houses varies sinusoidally with time. Such a current repeats its value after a finite time interval T, called the time period. So, the current is positive for one half period and is negative for the remaining half period. In reality it means that direction of current reverses after every half time period. An alternating current may be expressed asI = I_(w) sin (omega t + phi) where I_(m)is the peak value of current or the current amplitude. The mean current for a period T is definitely zero but mean of I^(2) over the same period is not zero because I^(2)is always positve. The average of l^(2)over a time period T or a long period of time isl_(m)^(2) = l_(m)^(2)/2 . The square root of mean square current is called rms current or virtual current and it is given asI_(rms) = I_(m)/sqrt(2) (a) What do you mean by sinusoidal nature of an alternating current ? |
| Answer» Solution :(a) By sinusoidal NATURE of an alternating current we mean that the GIVEN current is changing harmonically like a SINE or cosine FUNCTION of time and REPEATS itself after a time T, called its time period. | |
| 7992. |
To measure the alternating voltage developed across a resistance, we have to use : |
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Answer» a BALLISTIC GALVANOMETER |
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| 7993. |
Tarzan, who weighs 860 N, swings from a cliff att the end of a 20.0 m vine that hangs from a high tree limb and initially makes an angle of 22.0^(@) with the vertical. Assume that an x axis extends horizontally away from the cliff edge and a y axis extends upward. Immediately after Tarzan steps of the cliff, the tension in the vine is 760 N. Just then, what are (a) the force on him from the vine in unit-vector notation and as (c) a magnitude and (d)an angle relative to the positive direction of Tarzon's acceleration just then ? |
| Answer» Solution :(a) `(285N)hati+(705N)hatj,` (b) `(285N)hati-(155N)hatj,` ( C ) `324N,` (d) `-29.0^(@),` (e) `3.70" m"//"s"^(2),` (F) `-29.0^(@)` | |
| 7994. |
Statement I : Electrons in the conduction band have higher energy than those in valence bond. Statement II : The mobility of electrons is equal to mobility of holes . |
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Answer» STATEMENT I is true , statement II is FALSE. |
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| 7995. |
Read the passage given below and then answer questions on the basis of your under standing of the passage and the related studied concepts. Passage: When a resistor is connected across the terminals of a battery, a current is established in the circuit which has a unique direction going from positive terminal to the negative terminal via the external resistor. Magnitude of the current also remains practically constant. If the direction of the current in a resistor (or any other element) changes alternately, the current is called an alternating current. The alternating current being supplied in our houses varies sinusoidally with time. Such a current repeats its value after a finite time interval T, called the time period. So, the current is positive for one half period and is negative for the remaining half period. In reality it means that direction of current reverses after every half time period. An alternating current may be expressed asI = I_(w) sin (omega t + phi) where I_(m)is the peak value of current or the current amplitude. The mean current for a period T is definitely zero but mean of I^(2) over the same period is not zero because I^(2)is always positve. The average of l^(2)over a time period T or a long period of time isl_(m)^(2) = l_(m)^(2)/2 . The square root of mean square current is called rms current or virtual current and it is given asI_(rms) = I_(m)/sqrt(2) (c) In India our house hold supply is at 220 V and 50 Hz a.c. What does it mean to us? |
| Answer» SOLUTION :The rms VALUE of voltage in our HOUSE hold electric supply is 220 V and its frequency is 50 HZ i.e., its TIME period is `1/50` s or the current changes its sign after every `1/100` s. | |
| 7996. |
What is the effect on the interference fringes in a Young's double-slit experiment due to each of the following operations : the width of the source slit is increased, |
| Answer» SOLUTION :Same as in (d). As the source slit which increases, fringe pattern gets less and less SHARP. When the source slit is so wide that the CONDITION `s//S le lambda//d` is not satisfied, the interference pattern disappears. | |
| 7997. |
What is the effect on the interference fringes in a Young's double-slit experiment due to each of the following operations : the source slit is moved closer to the double-slit plane, |
| Answer» Solution :Let s be the size of the source and S its distance from the plane of the two slits. For interference fringes to be SEEN, the condition `s//S lt lambda//d` should be satisfied, otherwise, interference patterns produced by different parts of the source overlap and no fringes are seen. Thus, as S decreases (i.e., the source SLIT is brought closer), the interference pattern gets less and less SHARP, and when the source is brought too CLOSE for this condition to be valid, the fringes disappear. Till this happens, the FRINGE separation remains fixed. | |
| 7998. |
Read the passage given below and then answer questions on the basis of your under standing of the passage and the related studied concepts. Passage: When a resistor is connected across the terminals of a battery, a current is established in the circuit which has a unique direction going from positive terminal to the negative terminal via the external resistor. Magnitude of the current also remains practically constant. If the direction of the current in a resistor (or any other element) changes alternately, the current is called an alternating current. The alternating current being supplied in our houses varies sinusoidally with time. Such a current repeats its value after a finite time interval T, called the time period. So, the current is positive for one half period and is negative for the remaining half period. In reality it means that direction of current reverses after every half time period. An alternating current may be expressed asI = I_(w) sin (omega t + phi) where I_(m)is the peak value of current or the current amplitude. The mean current for a period T is definitely zero but mean of I^(2) over the same period is not zero because I^(2)is always positve. The average of l^(2)over a time period T or a long period of time isl_(m)^(2) = l_(m)^(2)/2 . The square root of mean square current is called rms current or virtual current and it is given asI_(rms) = I_(m)/sqrt(2) (b) Two alternating currents are expressed as I_(1) = I_(m) sin (omegat + phi) and I_(2) = I_(m) cos (omega t + phi). What is the difference between the two currents? |
| Answer» Solution :`I_(2)` and `I_(2)` have dame peak value, PERIOD (or frequency) but `I_(2)` is ahead phase by `pi/2` as compared to `I_(1)` as `I_(2)` MAY be expressed as `I_(2) = I_(m) COS (omega t + phi) = I_(m) SIN (omega t + phi + pi/2)` | |
| 7999. |
A place where the horizontal component of Earth's magnetic field is zero lies at .......... |
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Answer» geographic equator |
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| 8000. |
{:("List - I","List - II"),("A) Radio Iodine","e) Leukaemia"),("B) Radio sodium","f) age of ancient objects"),("C) Radio phosphorous ","g) Restriction in blood "),(,"circulation"),("D) Radio carbon","h) Functioning of "),(,"thyroid gland"):} |
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Answer» `A RARR h, B rarr G, Crarr e, D rarr F` |
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