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1., , 3., , , , The current passing through a choke coil, of 15 henry is decreasing at the rate of 0,2, ampere per second, The ¢.m.f. developed, across the coil :, , (A) 3 volt (B) 7.5 volt, , (C) 15 volt (D) 30 volt., , In a coil of area 10 cm? and 10 turns with, magnetic field directed perpendicular to, the plane and is changing at the rate of 10°, gauss/second. The resistance of the coil is, 20 ohm. The current in the coil will be :, , (A)S5A (B) 0.54, (C) 0.05 A (D) 5x10° A., (C.P.M.T. 1976), , A dynamo dissipates 25 watt when it supplies a current of 5 ampere through it. If, the the terminal potential difference is 220, volt then the e,m_f. produced in volts is :, , (A) 210 (B) 215, (C) 225 (D) 230., A 50 hertz alternating current of peak, value 2 ampere flows through the primary, coil of a transformer, If the mutual inductance between the primary and the, secondary be 0.5 henry then the peak, value of the induced voltage, is :, (A) 100 volt (B) 150 volt, (C) 200 volt (D) 250 volt., A coil of 10 emx 10 cm having 50 turns is, making 50 r.p.s. in a magnetic field of induction 2 tesla, The peak value of the, induced e.m.f. is approximately :, (A) 110 volt (B) 220 volt, (C) 314 volt (D) 628 volt. 7, The average e.m.f. induced in a coil in, which the current changes from 2 ampere, to 4 ampere in 0.05 second is 8 volt, what, is the self inductance of the coil ?, (A) 0.1 henry pa oe, 4 D enry., nes ‘ (P.M.T. 1986), citor of capacitance 1uF and a, 9 of eae 10° ohm are con, 9., , nected in series with a battery of e.m.f. 100, volt and negligible internal resistance., Then the time constant of the circuit is :, (A) 10-* s (B) 10s, , (C) 10-'s .(D) 1000 s., , A horizontal telegraph wire 0.5 kilometer, long runing cast and west is a part of a, circuit whose resistance is 2.5 ohm. The, wire falls to the ground from a height of 5, metres, Ifg = 10.0 m/s? and B = 2x10-5, weber per metre’, then the current induced in the circuit is :, , (A) 0.7 ampere (B) 0.02 ampere, , (C) 0.01 ampere (D) 0.04 ampere., , A magnetic needle lying parallel toa magnetic field requires W units of work to turn, it through 60°. The torque needed to maintain the needle in this position will be :, , (A) v3 W (B) W/V3, of (oy 24., , 10, Anelectric motor runs ona D.C. source of, , e.m.f, 220 V and internal resistance 119., Then the power output of the source is, maximum when the current drawn by the, motor is (Assume the resistance of armature zero.)., (A) 20A, (C)S5SA, , (B)10A, (D) 0., , 11. Anelectric motor runs on a D.C, source of, , e.m.f. 100 volt and draws a current of 5, ampere. If the efficiency is 25%, then the, resistance of the armature is :, , (A) 5 ohm (B) 10 ohm, , (C) 20 ohm (D) 40 ohm., , 12, The armature of a D.C. motor has 20 2, , resistance. It draws a current of 2.5, ampere when run by 220 volts D.C. supply., The value of back e.m.f, induced in it will, be:, , (A) 150 V, (C) 170 V, , (B) 160 V, (D) 180 V., , 13. With the decreases of current in the, , 143

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wee, i ‘coil from 2 ampere to zero value, Oots bo the cant geatrited in S, secondary coil is 1000 volt. The mutu:, inductance of the two coil is :, (A) 1.25 henry a ae, .00 hen D) 10.00 henry., magkey | (P.M.T. 1989), 14. A electric motor has a back e.m-f, of 110, volt and armature current of 90 ampere., The armature is making 25 r.p.s. Then the, power developed is :, (A) 110x25 watt (B) 11090 watt, (C) 90x25 watt —(D) 90x27 25 watt., (P.M.T. 1985), 15. When the number of turns in a solenoid is, doubled without any change in the length, of the solenoid, its self- inductance will be:, , (A) Fourtimes —_(B) Doubled, (C) Halved’ (D) Squared., (P.M.T. 1986), , 16. Acoilis wound ona former of rectangular, cross- section, If all the lincar dimensions, of the former are increased by a factor of, 3 and the numbers of turns per unit length, remains the same, the self-inductance in, creases by a factor of :, (A)3 (B)9, (C) 27 (D) 81., , 17, The armature of a 10 polar dynamo rates, making 600 r.p.m. What is the frequency, , of ac?, (A) 10 Hz (B) 30 Hz, (C) 50 Hz (D) 60 Hz., , 18. Two coils X and Y are placed in a circuit, such that a current changes by3 ampere in, coil X and the magnetic flux changes of 1.2, weber occcurs in Y. The value of mutual, inductance of the coils is :, , (A) 0.2 henry (B) 0.4 henry, (C) 0.6 henry (D) 3.6 henry., , 19. To reduce the loss of energy as heat due to, eddy currents, the soft iron core is, laminated. The angle between the plane of, these sheets and the magnetic induction, , should be :, (A) Zero (B) 45°, (C) 60° (D) 90°., , (P.M.T, 1985), , 20.. The current in a self inductance L = 40, , 21., , 22,, , 23., , 24,, , 25., , 26., , mH is to be increased unitary from |, to 1A in 4 milli seconds, The Wlinegy, cam.f, produced in | during Ube Pre, will be, , (A) 100 volt, (C) 440 volt, , (8) 0.4 volt, (D) 40 volt, , (CANE, 14), When the current ina coil changos tomy, ampere to 2ampere im 3x WW SeCONS thy, emf. induced in the coil is 2 volt. Ty,, self-inductance of the coil, in milli honty,, is:, (A) I, (C) 20, , (B) S, (D) 10., , (MLL.NR. 1097), Agalvanometer is connected (0 the seegy., dary coil. The galvanometer shows aq, instantaneous maximum deflection of 7, divisions when current is started in the, primary coil of the solenoid, Now if the, primary coil is rotated through 180°, then, the new instantancous maximum deflee, tion will be :, , (A) 7 units, (C) 0 units, , (B) 14 units, , (D) 21 units,, (C.P.M.T. 1991), , Whent the current changes from + 2A to, , —2 A in 0.05 second, an c.m.f. of 8 volt is, , induced in a coil, The coefficient of self, , induction of the coil is :, , (A) 0.1H (B)0.2H, , (C)04H (D) 0.8 H., , There is a current of 20 milliampere, , through an ideal choke coil of 1,5 H when, , connected to 220 volt, 50 hertz ac supply., , The power consumed is :, , (A) Zero (B) 220% 20% 107° wall, , (C) 22050 watt (DD) 22020 1.5 wall., , A coil of resistance 300 ohm and self in, ductance 1.5 henry is connected toan AC., , source of frequency 1004 henry. The phase, , difference between voltage and curren!, , (A) 0° (B) 30°, , (C) 45° (D) 60°. |, A group of electric lamps having 4 ae, power rating of 1000 watt is supplied by, AC, voltage, , E = 200 sin (3101-4-60°)

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27., , 28., , 29, , 30., , 31,, , :, , Then the r.m.s. value of the circuit current, is:, , (A) 10A (B) 10V2A, , (C)20A (D) 20 V2A., , Using an A.C. voltmeter, the potential difference in the electrical line in a house is, read to be 234 volt. If the line f requency is, , known to be 50 cycles pe, n : S per second, t, equation for the line voltage is : oo, , (A) V = 165 sin (100x ¢), (B) V = 331 sin (100xr 1), (C) V = 234 sin (100s), (D) V = 440 sin (100zrt),, , (P.M.T. 1987), A generator produces a voltage that is, given by V = 240 sin 120¢ volt where ¢ is in, , seconds. The frequency and rms voltage, are:, , (A) 60 Hz and 240 volt, , (B) 19 Hz and 120 volt, , (C) 19 Hz and 170 volt, , (D) 754 Hz and 170 volt. (PM.T. 1990), In a region of uniform magnetic induction, B = 10 tesla, a circular coil of radius 30, cm and resistance 2? ohm is rotated about, an axis which is perpendicular to the direction of B. and which forms a diameter of, the coil. If the coil rotates at 200 rpm the, amplitude of the alternating current induced in the coil is :, , (A) 42°mA (B) 30 mA, , (C)6mA (D) 200 mA., , (C.B.S.E. 1990), , An alternating voltage (in volts) =, 200V2 sin 100 ¢ is connected to one, microfarad capacitor through an ac ammeter. The reading of the ammeter shall, be:, , (A) 10 mA, (C) 40 mA, , (B) 20 mA, (D) 80 mA., , (C.P.M.T. 1991), , i ive circuit contains a resistance, , orto and an inductance of 2.0 henry., If an Ac voltage of 120 volt and frequcoey, 60 Hzis applied to this circuit, the cur!, in the circuit would be nearly :, (A) 0.32 ampere (B) 0.16 ps, (C) 0.48 ampere (D) 0.80 ampere., , ;, , 32,, , 33., , 34., , 35., , 36., , 37., , 38., , (C.P.M.T. 1990), The’ ratio of secondary to the primary, turns in a transformer is 5. If the power, output be P, the input power neglecting all, losses, must be equal to:, (A) 5P (B) VSP, (C) P/S (D) None of the above., In a step-up transformer the turn ratio is 3, : 2. A battery (c.m.f. 4.5 V) is connected, across the primary. The voltage developed, , in the secondary would be :, (A) 4.5V (B)3.0V, (C)15V (D) Zero., , An A.C. circuit using an inductor and a, capacitor in series has a maximum current., IfL = 0.5 henry and C = 8 yF then the, angular frequency of A.C, voltage will be :, (A) 500 (B) 5x10°, (C) 4000 (D) 5000., , (CP.M.T. 1991), , In an A.C, circuit the potential V and the, current are given respectively by, , V = 100 sin (100 ¢) volt and J = 100 sin, (100t +-2./3) mA., , The power dissipation in the circuit will be, , (A) 10* Watt, , (B) 10 Watt, (C)25 Watt (D) 5 Watt., (C.P.M.T. 1991), , The ratio of the mean valuc over half cycle, to the r.m.s. value of an A.C. is:, , (A) 2:2 (B)2V2:2, (C)v2:2 (D) v2:1., , A 20 volt A.C. is applicd to a circuit consisting of a resistance and a coil with a, negligible resistance. If the voltage acrass, the resistance is 12 volt, the voltage across, the coil is ;, , (A) 16 volt (B) 10 volt, (C) 8 volt (D) 6 volt., (P.M.T. 1989), , A transformer steps down 200 volt to 20, voll to operate a device with an impedance, of 200 ohm, Then the current drawn from, the mains by the primary of the transformer, is :, , (A) 0.2 ampere (B) 0.1 ampere, , (C) 0.01 ampere (D) 0.02 ampere.

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59., , 41., , ws \wreé, , When a deuterium is bombarded on .O'", nucleus, an a-particle is emitted, then the, product nucleus is [CBSE AIPMT 2002], (a);N'3— (b) B’’ (ce) ,Bo® ~~ (ds) , NI’, Which of the following are suitable for the, fusion process ? [CBSE AIPMT 2002], (a) Light nuclei, (b) Heavy nuclei, (c) Elements lying in the middle of periodic table, (d) Elements lying in the middle of binding energy, curve, A sample of radioactive elements contains, 4x10" active nuclei. If half-life of, element is 10 days, then the number of, decayed nuclei after 30 days is, , [CBSE AIPMT 2002], (a) 0.5 x 10'° (b) 2 x 10'°, (c) 3.5x 10° (d) 1x 10'°, , 42.1In compound X(n,@) > Li’, the element, , X is [CBSE AIPMT 2001], (a) pHe* = (b) ,B" ss (c) , B® (d) ,Be"’

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43. When intensity of incident light increases, [CBSE AIPMT 1999], , (a) photocurrent increases, , (b) photocurrent decreases, , (c) kinetic energy of emitted photoelectrons, increases, , (d) kinetic energy of emitted photoelectrons, decreases, , 44. The photoelectric work function for a metal, surface is 4.125 eV. The cut-off wavelength, for this surface is [CBSE AIPMT 1999], , (a) 4125A (b)3000A (c)6000A (d) 2062.5A, 45. In a photoemissive cell, with exciting, , wavelength i, the fastest electron has, , speed v. If the exciting wavelength is, , changed to 3A/4, the speed of the fastest, emitted electron will be [CBSE AIPMT 1998], , 3/2 4V"?, mY (;) , ee (5) 1/2, , 1/2, (c) less than v (| (d) greater than v (=)