45406 + Interview Questions in Physics in Class 12 Page 756 InterviewSolution

37751.	From Brewster's law, except for polished metallic surfaces, the polarising angle
Answer» depends on wavelength and SI DIFFERENT for different colours independent of wavelength and is different for different colours independent of wavelength and is same for different colours depends on wavelength and is same for different colours Solution :From Brewster's LAWS `i_(p)="tan"^(-1)(mu)` i.e., the polarising ANGLE depends on refractive INDEX and hence on wavelength and therefore is different for different colours.

Discussion

37752.	A magnet was inserted into a wire ring connected to a ballistic galvanometer of 30 ohm resistance, this causing 20 division deflection of the galvonometer printer. What magnetic flux passes through the pole pices of the magnet. If the galvonometer constant is 3 xx 10^(-5)"C/div"? Neglect the resistance of the resistance of the ring and of the leads.
Answer» Solution :The INDUCED e.m.f. is `delta=-(triangle PSI)/(trianglet)=(Psi)/(trianglet)` SINCE initially the magnetic flux, through the ring is zero. The change flowing through the circuit is `\|triangle\|=epsi/R triangle t=(Psi)/R` It is equal to the galvonometer CONSTANT multiplied by the number of scale DIVISIONS q=CN.

Discussion

37753.	A tuning fork of frequency 340 Hz is vibrated just above a cylindrical tube of length 120 cm. Water is slowly poured in the tube. If the speed of sound is 340 ms^(-1)then the minimum height of water required for resonance is:
Answer» 95cm 75cm 45cm 25cm Answer :C

Discussion

37754.	A car weighing 100kg is on a slope that makes an angle 30^(@) with the horizontal. The component of car's weight parallel to the slope is (g=10 ms^(-2))
Answer» 500 N 1000 N 15,000 N 20,000 N Answer :A

Discussion

37755.	Light with an energy flux of 18W//cm^(2) falls on a non-reflecting surface at normal incidence. If the surface has an area of 20cm^(2), find the average force exerted on the surface during a 30 minute time span.
Answer» <P> Solution :The total energy falling on the surface is `U=(18 W//cm^(2))xx(20 cm^(2))xx(30xx60 s)` `=6.48 xx10^(5) J` Therefore, the total MOMENTUM delivered (for complete absorption) is `p=(U)/(c )=(6.48xx10^(5) J)/(3xx10^(8) m//s)=2.16 xx10^(-3) kg m//s` The AVERAGE force EXERTED on the surface is `F=(p)/(t) =(2.16 xx10^(-3)/(0.18xx10^(4))=1.2xx10^(-6) N` How will your result be modified if the surface is a perfect reflector?

Discussion

37756.	Two Rods of same cross sectional area and same length but different thermal conductivity K_(1) and K_(2) are first connected in series and then connected in parallel between same temperature difference in both cases Then the ratio of rates of heat flow in both cases is.
Answer» `(4k_(1)k_(2))/((k_(1)+k_(2))^(2))` none `((k_(1)+k_(2))/(k_(1)-k_(2)))` `(k_(1)k_(2))/((k_(1)+k_(2))^(2))` SOLUTION :`y=Asin(kx-omegat)` `(v_("PARTICLE"))_("max")=Aomega=(2piAV)/(lambda)` WAVE speed `=v=(omega)/(k)`

Discussion

37757.	In figure, light refracts from material 1 to a thin layer of material 2, crosses that layer, and then is incident at the critical angle on the interface between materials 2 and 3. (a) What is the angle theta? (b) if theta is decreased, is there refraction of light into material 3?
Answer» SOLUTION : `mu_1 sin i_1=mu_2sin i_2=mu_2sin theta_C` `(1.6) sin THETA=(1.80)(1.30/1.80)` `:.theta=sin^-1(13/16)` If `theta` decreased, then `i_2` will decrease from the VALUE `theta_C.` Hence, refraction will take place in medium-3.

Discussion

37758.	The relation between Young's modulus (Y) modulus of rigidity (eta) and Poisson's ratio (sigma) is
Answer» `Y=2eta(1-sigma)` `Y=2eta(1+sigma)` `Y=eta(1-2sigma)` `Y=2eta(1+2sigma)` ANSWER :B

Discussion

37759.	In a gravity free space, there is a large spherical metal shell which is given a charge +Q_0. Inside the shell, a small particle having charge +q_0 is placed at the centre of the shell. Finally, what will be the co-ordinates of the particle? (Given that all the collisions are perfectly inelastic.)
Answer» (0,0) (0,R) (0,-R) NONE of these ANSWER :A

Discussion

37760.	For the circuit shown, with R_1=1.0Omega, R_2=2.0Omega, E_1=2V and E_2=E_3=4V the potential difference between the points 'a' and 'b' is approximately (in V):
Answer» 2.7 2.3 3.7 3.3 Answer :3.3

Discussion

37761.	The alternate discs of iron and carbon, having same area of cross-section are cemented together to make a cylinder whose temperature coefficient of resistivity is zero. The change in temperature in two alternate discs is same. The ratio of their thickness and ratio of heat produced in them is found out. The resistivity of iron and carbon at 20^@C" are "1 xx 10^(-7) and 3 xx 10^(-5)Omegam and their temperature coefficient of resistance are 5 xx 10^(-3)""^(@)C and -7.5 xx 10^(-4)""^(@)C, respectively, Thermal expansion is neglected. Here, triangleR_1 +triangleR_2= 0 (where triangleR_1, and triangleR_2, are the increase in resistances of iron and carbon, respectively, with the rise in temperature) because combined temperature coefficient of resistivity is given as zero. Ratio of heat produced in them is
Answer» 0.51 1 0.15 2 Answer :C

Discussion

37762.	The ratio of magnetic potentials due to magnetic dipole in the end-on position to that in the broad side on position for the same distance from it is -
Answer» zero 1 2 `00` Solution :V=(KMcostheta)/(R^(2)),V_("axis")=(KM)/(r^(2))becausetheta=0` `V_("equator")=0becausetheta=90^(@)RARR(V_("axis"))/(V_("equator"))=oo`

Discussion

37763.	The alternate discs of iron and carbon, having same area of cross-section are cemented together to make a cylinder whose temperature coefficient of resistivity is zero. The change in temperature in two alternate discs is same. The ratio of their thickness and ratio of heat produced in them is found out. The resistivity of iron and carbon at 20^@C" are "1 xx 10^(-7) and 3 xx 10^(-5)Omegam and their temperature coefficient of resistance are 5 xx 10^(-3)""^(@)C and -7.5 xx 10^(-4)""^(@)C, respectively, Thermal expansion is neglected. Here, triangleR_1 +triangleR_2= 0 (where triangleR_1, and triangleR_2, are the increase in resistances of iron and carbon, respectively, with the rise in temperature) because combined temperature coefficient of resistivity is given as zero. Ratio of their thickness is
Answer» 54 45 35 21 Answer :B

Discussion

37764.	The path difference between two interfering waves at a point on the screen is lambda"/"6from central maximum. The ratio of intensity at this point and that at the central fringe will be
Answer» `0.75` `7.5` `85.3` `853` ANSWER :A

Discussion

37765.	How long will light take in travelling a distance of 300 m in glass? R.l. of glass is 1.5 and velocity of light in vacuum 3xx10^8 m/s:
Answer» `10^(-6)s` Is `1.5xx10^(-6)s` `1xx10^(-4)s` ANSWER :C

Discussion

37766.	Who is a protagonist?
Answer» A Hero A SIDE character Prediction None of the above Answer :A

Discussion

37767.	Two simple harmonic motions are given by x_(1) = a sin omegat + a cos omega t and x_(2) = asin omegat + a/sqrt(3) 01. The ratio of the amplitudes of first and second motion and the phase difference between them are respectively
Answer» `sqrt(3/2)` and `pi/12` `sqrt(3)/2` and `pi/12` `2/sqrt(3)` and `pi/12` `sqrt(3/2)` and `pi/6` Solution :For first simple HARMONIC motion, `x_(1) = a sin omega t + a cos omegat` `=sqrt(2)a [1/sqrt(2) sin omegat + 1/sqrt(2) cos omegat]` `=sqrt(2)a sin (omegat + pi/4)` `THEREFORE` Amplitude of this simple harmonic motion is, `a_(1) = sqrt(2)a` and phase of the simple harmonic motion is, `phi_(1) =pi/4` For second simple harmonic motion, `x_(2) =a sin omegat + a/sqrt(3) cos omegat` `=(2a)/sqrt(3)[sqrt(3)/2 sin omegat + 1/2 cos omegat]` `(2a)/sqrt(3)sin(omegat + pi/6)` `therefore` Amplitude of this simple harmonic motion is, `a_(2) =(2a)/sqrt(3)` and phase of this simple harmonic motion is, `phi_(2) = pi/6` The ratio of their amplitudes is `a_(1)/a_(2) =(sqrt(2)a)/((2a)/sqrt(3)) = sqrt(3/2)` Phase difference between them is, `Deltaphi = phi_(1) - phi_(2) = pi/4 - pi/6 =(6pi - 4PI)/24 = (2pi)/24 = pi/12`

Discussion

37768.	The alternate discs of iron and carbon, having same area of cross-section are cemented together to make a cylinder whose temperature coefficient of resistivity is zero. The change in temperature in two alternate discs is same. The ratio of their thickness and ratio of heat produced in them is found out. The resistivity of iron and carbon at 20^@C" are "1 xx 10^(-7) and 3 xx 10^(-5)Omegam and their temperature coefficient of resistance are 5 xx 10^(-3)""^(@)C and -7.5 xx 10^(-4)""^(@)C, respectively, Thermal expansion is neglected. Here, triangleR_1 +triangleR_2= 0 (where triangleR_1, and triangleR_2, are the increase in resistances of iron and carbon, respectively, with the rise in temperature) because combined temperature coefficient of resistivity is given as zero. A copper wire is stretched to make it 1% longer. The percentage change in its resistance is Electrical resistance of certain materials, known as super conductors changes abruptly from a non zero value to zero as their temperture is lowered below a critical temperature T_c(0) An interesting property of superconductors is that their critical temperature becomes smaller than T_c(0) if they are placed in a magnetic field, that is, the critical temperature T_c(B) is a function of the magnetic field strength B. The dependence of T_c(P) on magnetic field is shown in the below figure.
Answer» 0.002 0.01 0.015 0.025 Answer :A

Discussion

37769.	Show that the de-Broglie wavelength A of an electron of energy E is given by the relation : lambda = h/sqrt(2mE).
Answer» SOLUTION :Let E be energy and p MOMENTUM of electron, So `E = 1/2mv^(2) = (m^(2)v^(2))/(2m) =p^(2)/(2m)` or `p=sqrt(2mE)`……(i) Since de-Broglie wavelength associated by an electron is GIVEN by: `lambda = h/p` USING Eq. (i), we get `lambda = h/sqrt(2mE)`...........(ii)

Discussion

37770.	Who was deaf in the lesson?
Answer» Evelyn Ron Forbes Bismillah Khan Evelyn's mother Answer :A

Discussion

37771.	A uniformly tapering circular bar has its diameter ranging from (D-a) to (D+a) along its length L. The bar is subjected to an axial force P and young's modulus is Y. The percentage error in the calculation of elongation of bar if mean diameter is used in calculation instead of actual diameter.
Answer» `(2a^2)/(D^2)xx100` `((10A)/D)^2` `((a)/(10D))^2` `a/Dxx100` Answer :B

Discussion

37772.	Cosntant DC voltage is required from a variable AC voltage . Which of the following is correct order of operation ?
Answer» REGULATOR, FILTER, RECTIFIER Rectifier, regulator, filter Rectifier, filter, regulator Filter, regulator, rectifier SOLUTION :Rectifier, filter, regulator

Discussion

37773.	Two shortbar magnets of magnetic moment M each are arranged at the opposite corners of a square of sided such that their centrecoincide withthecorners same directio the magneticinducition at any of theother corner of the squre is
Answer» `(mu_(0))/(4pi)(m)/(d^(3))` `(mu_(0))/(4pi)(msqrt(2))/(d^(3))` `(mu_(0))/(4pi)(msqrt(5))/(d^(3))` `(mu_(0))/(4pi).(3m)/(d^(3))` SOLUTION :Magnetic field at Zon equationrial line at a DISTANCE from center of shortmagnet at corner `Z.B_(2)(mu_(0))/(4pi)(M)/(d^(3))` `because` like polesarein same DIRECTION so netmagnetic field`Z(B)=B_(1)-B_(2)=(mu_(0))/(4pi)(M)/(d^(3))`

Discussion

37774.	What did Rutherford's experiments on alpha particles cattering indicate about the structure of the atom?
Answer» Atoms are roughly sperical with a radius of about `10^(-10)`m. The electrons OCCUPY quantized energy LEVELS, absorbing or emitting energy only when theymake a QUANTUM jump between these levels. The density of positive charge within an atom is not uniform throughout the atom's volume. Allowed ELECTRON orbits must have a circumference equal to a whole number times the electron's de BROGLIE wavelength. Answer :C

Discussion

37775.	A field of 100Vm^(-1) is directed at 30^(@) to positive x -axis. Find V_(BA) if OA = 2m and OB = 4m
Answer» ANSWER :`100(SQRT(3)-2)V`

Discussion

37776.	A ray is incident at a small angle theta on a glass slab of thickness t. If the refractive index of glass is mu , show that the lateral displacement of the emergent ray from the slab is t theta(mu - 1) //mu.
Answer» SOLUTION :Lateral DISPLACEMENT of the emergent ray BD relative to the INCIDENT ray AO is BC [Fig. 2.75]. `therefore "" BC = OB(BC)/(OB) = OP(OB)/(OP)(BC)/(OB)` `= OP sec angleBOP SIN angleBOC` `= t sec theta. sin(theta - theta.)` `theta and theta. "being small we have",` `sce theta. = (1)/(costheta) approx (1)/(1) = 1 and sin(theta - theta.) approx theta - theta.` `therefore "" BC = t(theta - theta.) = t theta(1 - (theta.)/(theta))` `"again," mu = (sintheta)/(sintheta.) approx = (theta)/(theta.) or, (1)/(mu) = (theta.)/(theta)` `therefore "" "Lateral displacement,"` `BC = t theta(1 - (1)/(mu)) = t theta((mu - 1))/(mu)`

Discussion

37777.	A proton of charge 1.6 xx10^(-19)C is moving with a velocity 10^5m//s in auniform magnetic inductation 10^(-4)(Wb)//m^2,perpendicular to the direction of the motion of the proton ,force acting on the proton is :
Answer» `1.6xx10^(-19)N` `1.6xx10^19N` `1.6xx10^(-8)N` `1.6xx10(-18)N` ANSWER :D

Discussion

37778.	At what temperature semiconductor behaves as conductor?
Answer» `0^(@)C` 0 K `0^(@)F` at ROOM Answer :B

Discussion

37779.	Which of the statements below is correct?
Answer» The angle of bank for a ROAD isobtained from a consideration of the centripetal force required There is no TENDENCY for the vehicle to skid if a road is banked for the speed at which the vehicle is moving The resultant force action on a vehicle will be that which maintains it in a circular path All of the above STATEMENTS are correct. Solution :All of the above are true statements REGARDING the banking of a roadbed

Discussion

37780.	The pole near the geographic north pole is called ....... The pole near the geographic south pole is called …......
Answer» SOLUTION :(i) NORTH MAGNETIC pole, (II) SOUTH magnetic pole

Discussion

37781.	Assuming the potential well to contain three bosons. The energy of the system is at its minimum.
Answer» Solution :The Pauli exclusion principle does not hold for bosons. Therefore in a SYSTEM in a STATE of minimum ENERGY, all three particles will occupy the first energy level. Since in this case their momenta are equal, the force of pressure turns out to be three times GREATER.

Discussion

37782.	A whistle producting sound waves of frequencies 9500 Hz and above is approaching a stationary person with v ms^(-1). The velocity of sound in air is 300 ms^(-1) . If a person can hear frequencies upto 10,000 Hz, the maximum value of v upto which he can hear the whistle is :
Answer» `15 SQRT(2) ms^(-1) ` `(15)/(sqrt(2)) ms^(-1)` `15 ms^(-1)` `30 ms^(-1)` Solution :APPARENT frequency `v. = ((V)/(V - U_(s)) ) .v` 10,000 = `((300)/(300 - U_(s)) ) . 9500` `rArr U_(s) = 15 ms^(-1)`. So correct CHOICE is (C).

Discussion

37783.	Assertion (A): The surface of spherical conductor can be considered as an equipotentialsurface. Reason (R) : In a conductor charges can easily flow till potential is same at the entire surface.
Answer» If both ASSERTION and REASON are true and the reason is the correct explanation of the assertion. If both assertion and reason are true but reason is not the correct explanation of the assertion. If assertion is true but reason is FALSE. If the assertion is false but reason is true. SOLUTION :Assertion and reason both are true and reason gives correct explanation for assertion.

Discussion

37784.	When a charged conductor is placed ln an external electric field, inside the conductor we have ...... .
Answer» `E NE 0, V ne 0` `E =0 , V ne 0` `E ne 0 , V =0` `E =0 , V=0`

Discussion

37785.	Referring to the above question, match Column-I and II.
Answer» `{:("P","Q","R","S"),("2","3","1","4"):}` `{:("P","Q","R","S"),("1","4","2","3"):}` `{:("P","Q","R","S"),("1","2","3","3"):}` `{:("P","Q","R","S"),("3","1","4","2"):}` ANSWER :C

Discussion

37786.	In the circuit shown in fig. the capacitor is initially uncharged. Two way switch (s) is placed in position 1 for a very short interval of time (Delta t) and then is moved to position 2. The switch is held in position 2 for equally short interval Delta t and is then moved back to position 1. The process is repeated a large number of times until the charge on the capacitor stops changing. find this final a value of charge on the capacitor. [Assume that in each contact the charge on the capacitor changes by a very small amount]
Answer» ANSWER :`7 MUF`

Discussion

37787.	The wavelength of light received from a galaxy is 10% greater than that received from identical source on the earth. The velocity of the galaxy relative to the earth is
Answer» `3XX 10^(8) MS^(-1)` `3xx 10^(7) ms^(-1)` `3xx 10^(6) ms^(-1)` `3xx 10^(5) ms^(-1)` Answer :B

Discussion

37788.	When we raise the temperature of a body, the molecules and atoms move with greater kinetic enery. Assume that "the temperature" is the manifestation of only the kinetic energy is atomic and subatomic levels and no mass change (excess//defect) occurs due to heating. Now a solid material is supplied with heat at a constant rate.The temperature of the material is changing with the heat input as shown in the graph. BC and DE are parallel to the Heat-input axis In AB, CD and EF, the energy of the system increases. Here "energy" refers to
Answer» KINETIC energy potential energy both kinetic and potential energy none of these Solution :In `AB`, `CD` and `EF` TEMPERATURE INCREASES `rArr K.E.` increases

Discussion

37789.	When we raise the temperature of a body, the molecules and atoms move with greater kinetic enery. Assume that "the temperature" is the manifestation of only the kinetic energy is atomic and subatomic levels and no mass change (excess//defect) occurs due to heating. Now a solid material is supplied with heat at a constant rate.The temperature of the material is changing with the heat input as shown in the graph. BC and DE are parallel to the Heat-input axis In which of the following phase the assumption made in the above comprehension is most precise ?
Answer» solid liquid gas not predictable Solution :In GASES, there is no APPRECIABLE MOLECULAR INTERACTION.

Discussion

37790.	When we raise the temperature of a body, the molecules and atoms move with greater kinetic enery. Assume that "the temperature" is the manifestation of only the kinetic energy is atomic and subatomic levels and no mass change (excess//defect) occurs due to heating. Now a solid material is supplied with heat at a constant rate.The temperature of the material is changing with the heat input as shown in the graph. BC and DE are parallel to the Heat-input axis In BC and DE
Answer» kinetic ENERGY increases potential energy increases kinetic energy decreases potential energy REMAINS CONSTANT Solution :In `BC` and `DE` temperature remains constant `rArr K.E.` remains constant `rArr` HEAT goes to increasing the `P.E.`

Discussion

37791.	The following ligure shows the cross section of a wire. Which of the following statement(s) about current (l) and drift velocity (v) is true?
Answer» `I_(A)=I_(B)=I_(C) and v_(A)=v_(C) GT v_(B)` `I_(A)=I_(B)=I_(C) and v_(A) gt v_(C) gt v_(B)` `I_(A) =I_(B) LT l_(C) and v_(A)=v_(C)=v_(B)` `I_(A) =I_(B) = l_(C) and v_(A) lt v_(C) ltv_(B)` ANSWER :D

Discussion

37792.	In the question number 66, the flux through the same square if the line normal to its plane makes a 60^(@) angle with the x-axis is
Answer» `30NC^(-1)m^(2)` `10NC^(-1)m^(2)` `20NC^(-1)m^(2)` `25NC^(-1)m^(2)` SOLUTION :When normal to the plane MAKES an angle of `60^(@)` with x-axis, then `theta=60^(@)` `phi=Escostheta=2xx10^(3)xx10^(-2)cos60^(@)=10NC^(-1)m^(2)`

Discussion

37793.	The magnetic susceptibility of a superconductor is
Answer» `chi_m=1` `chi_m=-1` `chi_m=0` `chi_m=oo` ANSWER :B

Discussion

37794.	Area vector of a coil of 5 xx 10^(-3)m^2makes an angle of 0^@ with a uniform magnetic field. If from this position the coil is rotated in 0.5 sec., so that the angle made by area vector with the field becomes 90^@. Find the average emf induced in the coil. The magnetic field intensity is 0.3 T. Number of turns in the coil is 500.
Answer» 1.5 V 2.5 V 1.4 V 1.3 V Solution :Here, N=500 `A=5xx10^(-3) m^2` `Deltat` = 0.5 s `theta_1=0^@` `theta_2=90^@` B=0.3 T `rArr` FLUX in coil `phi_1=AB COS theta_1` and `phi_2=AB cos theta_2` Change in flux `Deltaphi=phi_2-phi_1` `=AB cos theta_2-AB cos theta_1` `=AB[cos theta_2-cos theta_1]` `=AB [cos 90^@ - cos 0^@]` =AB[0-1]=-AB `therefore` Induced EMF in coil, `E=-N(Deltaphi)/(Deltat)` `=-N((-AB))/(Deltat)` `=(NAB)/(Deltat)` `=(500xx5xx10^(-3)xx0.3)/0.5` `therefore` E=1.5 V

Discussion

37795.	Statement I: Nuclear forces' are charge independent. Statement II: The nuclear forces act between nucleons only.
Answer» A Statement I is TRUE, statement II is false. Statement I is false, statement II is true. C Statement I is true, statement II is true, Statement II is CORRECT EXPLANATION of statement I. Statement I is true, statement II is true and statement I is not correct explanation of statement II. Answer :C

Discussion

37796.	In a double slit experiment, the distance between the slits is 3 mm and the slits are 2 m away from the screen. Two interference patterns can be seen on the screen one due to light with wavelength 480 nm, and the other due to light with wavelength 600 nm. What is the separation on the screen between the fifth order bright fringes of the two interference patterns?
Answer» Solution :`beta=lambda.D//d` 5th BRIGHT `=5beta_(1)=5lambdaD//d=5 XX 480 xx 10^(-9) xx 2//3 xx 10^(-3)=16 xx 10^(-4)m` 5th bright `=5beta_(2)=Slambda1D//d=5 xx 600 xx 10^(-9) xx 2//3 xx 10^(-3) =20 xx 10^(-4)m` distance between two 5th bright fringes `=(20-16)xx 10^(-4) =4 xx 10^(-4)m`

Discussion

37797.	How AC is represented Mathematically ?
Answer» SOLUTION :E= E_0 SIN `OMEGA t`

Discussion

37798.	(A):The relative velocity between any two bodies moving In opposite direction Is equal to sum of the velocities of two bodies. (R ):Sometimes relative velocity between two bodies is equal to difference in velocities of the two bodies.
Answer» ANSWER :B

Discussion

37799.	One morning an old man walked bare-foot to replacce the fuse wire in kit kat fitted with the power supply mains for his house. Suddenly he screamed and collapsed on the floor. His wife cried loudly for help. His neighbour's son Anil heard the crises and rushed to the place with shoes on. He took a wooden baton and used it to switch off the main supply . Answer the following questions. (i) what is the voltage and frequency of mains supply in India ? (iii) Can a transformer be used to step up d.c. voltage ? (iv) write two qualities displayed by Anil by his action.
Answer» Solution :(i) Voltage = 220 V Frequency = 50 Hz. (ii) (a) AC CURRENT is MUCH easier to produce. (b) The cost of DC to AC is reltively high. © The direction of the current flow is reversed. Due to this property, we can jerk, and avoid from SUPPLY to step up. (iii) No, reason-This is only possible if the primary current is also changing . Hence the transforme on a.c. supply to step up. (iv) (i) He switched off the main supply which MEANS, he stopped to flow of current from further electric shocks. (v) (a) He saved the precious life of human. (b) , He used safety rules to protect an old man.

Discussion

37800.	Figure shows a series LCR circuit connected to a variable frequency 230 V source. L = 5.0 H, C = 80 muF, R= 40Omega a. Determine the source frequency which drives the circuit in resonanceb. Obtain the impedance of the circuit and the amplitude of current at the resonating frequency. c. Determine the rms potential drops across the three elements of the circuit. Show that the potential drop across the LC combination is zero at the rasonating frequency.
Answer» Solution :a. `omega = (1)/(sqrtLC) = (1)/(sqrt(5 xx 80 xx 10^(-6) )`= 50 rad/sec b. At RESONANCE `Z = R = 40 Omega` `I_(RMS) = (V_(rms) )/(R ) = (230 sqrt2)/(40) = 8A` c.`V_L = IX_L = I omega L = 8 xx 50 xx 5= 2000 V` `V_C = IX_C = (I)/(omega C) = (8)/(50 xx 80 xx 10^(-6) ) = 200 V, V_R = 230 V , V_L- V_C = 0` i.e., potential drop across LC combination is zero .

Discussion

Explore topic-wise InterviewSolutions in .

From Brewster's law, except for polished metallic surfaces, the polarising angle

A tuning fork of frequency 340 Hz is vibrated just above a cylindrical tube of length 120 cm. Water is slowly poured in the tube. If the speed of sound is 340 ms^(-1)then the minimum height of water required for resonance is:

A car weighing 100kg is on a slope that makes an angle 30^(@) with the horizontal. The component of car's weight parallel to the slope is (g=10 ms^(-2))

Light with an energy flux of 18W//cm^(2) falls on a non-reflecting surface at normal incidence. If the surface has an area of 20cm^(2), find the average force exerted on the surface during a 30 minute time span.

Two Rods of same cross sectional area and same length but different thermal conductivity K_(1) and K_(2) are first connected in series and then connected in parallel between same temperature difference in both cases Then the ratio of rates of heat flow in both cases is.

In figure, light refracts from material 1 to a thin layer of material 2, crosses that layer, and then is incident at the critical angle on the interface between materials 2 and 3. (a) What is the angle theta? (b) if theta is decreased, is there refraction of light into material 3?

The relation between Young's modulus (Y) modulus of rigidity (eta) and Poisson's ratio (sigma) is

In a gravity free space, there is a large spherical metal shell which is given a charge +Q_0. Inside the shell, a small particle having charge +q_0 is placed at the centre of the shell. Finally, what will be the co-ordinates of the particle? (Given that all the collisions are perfectly inelastic.)

For the circuit shown, with R_1=1.0Omega, R_2=2.0Omega, E_1=2V and E_2=E_3=4V the potential difference between the points 'a' and 'b' is approximately (in V):

The ratio of magnetic potentials due to magnetic dipole in the end-on position to that in the broad side on position for the same distance from it is -

The path difference between two interfering waves at a point on the screen is lambda"/"6from central maximum. The ratio of intensity at this point and that at the central fringe will be

How long will light take in travelling a distance of 300 m in glass? R.l. of glass is 1.5 and velocity of light in vacuum 3xx10^8 m/s:

Who is a protagonist?

Two simple harmonic motions are given by x_(1) = a sin omegat + a cos omega t and x_(2) = asin omegat + a/sqrt(3) 01. The ratio of the amplitudes of first and second motion and the phase difference between them are respectively

Show that the de-Broglie wavelength A of an electron of energy E is given by the relation : lambda = h/sqrt(2mE).

Who was deaf in the lesson?

A uniformly tapering circular bar has its diameter ranging from (D-a) to (D+a) along its length L. The bar is subjected to an axial force P and young's modulus is Y. The percentage error in the calculation of elongation of bar if mean diameter is used in calculation instead of actual diameter.

Cosntant DC voltage is required from a variable AC voltage . Which of the following is correct order of operation ?

Two shortbar magnets of magnetic moment M each are arranged at the opposite corners of a square of sided such that their centrecoincide withthecorners same directio the magneticinducition at any of theother corner of the squre is

What did Rutherford's experiments on alpha particles cattering indicate about the structure of the atom?

A field of 100Vm^(-1) is directed at 30^(@) to positive x -axis. Find V_(BA) if OA = 2m and OB = 4m

A ray is incident at a small angle theta on a glass slab of thickness t. If the refractive index of glass is mu , show that the lateral displacement of the emergent ray from the slab is t theta(mu - 1) //mu.

A proton of charge 1.6 xx10^(-19)C is moving with a velocity 10^5m//s in auniform magnetic inductation 10^(-4)(Wb)//m^2,perpendicular to the direction of the motion of the proton ,force acting on the proton is :

At what temperature semiconductor behaves as conductor?

Which of the statements below is correct?

The pole near the geographic north pole is called ....... The pole near the geographic south pole is called …......

Assuming the potential well to contain three bosons. The energy of the system is at its minimum.

A whistle producting sound waves of frequencies 9500 Hz and above is approaching a stationary person with v ms^(-1). The velocity of sound in air is 300 ms^(-1) . If a person can hear frequencies upto 10,000 Hz, the maximum value of v upto which he can hear the whistle is :

Assertion (A): The surface of spherical conductor can be considered as an equipotentialsurface. Reason (R) : In a conductor charges can easily flow till potential is same at the entire surface.

When a charged conductor is placed ln an external electric field, inside the conductor we have ...... .

Referring to the above question, match Column-I and II.

The wavelength of light received from a galaxy is 10% greater than that received from identical source on the earth. The velocity of the galaxy relative to the earth is

The following ligure shows the cross section of a wire. Which of the following statement(s) about current (l) and drift velocity (v) is true?

In the question number 66, the flux through the same square if the line normal to its plane makes a 60^(@) angle with the x-axis is

The magnetic susceptibility of a superconductor is

Statement I: Nuclear forces' are charge independent. Statement II: The nuclear forces act between nucleons only.

How AC is represented Mathematically ?

(A):The relative velocity between any two bodies moving In opposite direction Is equal to sum of the velocities of two bodies. (R ):Sometimes relative velocity between two bodies is equal to difference in velocities of the two bodies.