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50, , PHYSIcs, , 4. mvs, , vIDYA MaK marks, , CLASs 12, , is the SI unit of which of the, , dissipated in a resistor R on the, it and the voltage across it., , urrent, , through, , following?, , 7. 1f the ammeter in the given circuit shown in, , (A) Drift velocity, , reads 2A, the resistance R is, (B) 22, , thediagram, , (B) Mobility, (C) Resistance, , (A) 1, , (D) Potential gradient, , (C) 32, , (D) 42, , heater is rated (, , If it, , V)., , is connected across a source of voltage, then the power consumed by it will be :, (B) 2P, (A)P, , Explanation:, , V, , V= IR, , 6 2(2+ R), , 3 2 +, , PV2, , the accuracy. Which of the, , accurately., , R, , R, , and Rz, , and, , ratio of power dissipated in them, P,:P2 will, be:, (A) 4:9, , (D) 2:3, , C)9:4, , (D) Neither, , drift, , velocity, , nor, , thermal, , in, o, The amount of charge on, , the capacitor plates will be :, , R, w, , 4 uF, , (B) The equivalent emí Eq is smaller than E, (C) The E, , is given by E, , is independent, and r2, , (D) E, , Ans. (A) The equivalent emf E, , 102, , between, , E, , = E1 + E^ always., , of internal resistance, , E, , 1R+, R+r=, R, , E, , =, , 10, , R 2 0 - 3 = 17, , 13. If the plot of the variation of potential, difference across a combination of three, identical cells in series, versus current, is shown below. The emf and internal, resistance of each cell is :, , (A) 6 V,6Q2, , (B) 5V.6, , (C)5V5Q, , (D) 6V,3Q, , Voltage, , When, Then,, from the graph,, When, , I, , E, , E- I, =, , E, , I =0A,, E =6V, , and, , www, , (C) 16 C, the arcuit comes rom the chemical energy of, the cell which supplies the, power as long as, it, can. The expressions for power i.e., P lHR, V/R shows the, dependence of the power, =, , 12. A battery of emí 10 V and internal resistance, , (B) 4 C, (D) 8 C, , 399 is connected to a resistor. If the current in, the circuit is 0.5A, then the resistance of the, , Ans. (D) 8 C, , 2.5, Explanation: I= R+r2+0.5, , resistoris, =, , V IR =1 x 2 = 2V, Q =CV = 4uF x 2V = Bu, , = 6V, , I = 1 A, V = 0, , When, , 0 6-7, , <E, , v2, (A) 0 C, , cell, , = 0, , =6, , 14. The, , relation of mobility, , relaxation time is, , 2, , across, , of the two cells is, , and E, ie, E, <, , w, R, , Related Theory : The power dissipated in, , =20, , 20-7, , V = E - Ir, , Explanation: Their equivalent emfis, , =, , I= 0.5 A, , V, (A) The equivalent emf E of the two cells is, between E, and E, ie., E < Eag < E2, , the battery is 0.5 2, , Explanation:, , r=3, , Current,, , combination,, , (C) Both drift velocity and thermal velocity, , Ans. (A) Drist velocity alone., 9. A capacitor of 4 uF is connected as shown, the figure below. The internal resistance, , Ans. (B) 3:2, , E=10 V, , Explanation, , (B) Thermal velocity alone., , veloaty, , (B) 3:2, , EME, , Internal resistance,, , Ans. (A) 6 V,62, , (A) Drift velocity alone., , of 4, 6 are, 6. Two resistors R,, connected in paraliel across a battery. The, , Explanation: Given:, , A, , conductor ?, , P will become, , Ans. (C) 17n, , 12, , 8. Which of the following characteristics, of electrons determines the current in a, , If, , 51, , more larger distance. So, if there is a small, error in measuring distance the measure of R, will not be deflected too much., 11. Two batteries of emf E and E (E, > E,) and, internal resistances ri and r respectively are, connected in parallel as shown in figure., , 6V, , 2+R, , Since, resistance remain same for a heater, , improve, , experiment., Explanation: Changing S to 1000 will give, , =, , I= 2A,, , P, , = 2.9 cm. He is told to attempt, , Ans. (B) He should change S to 3 and repeat the, , equivalent, , Explanation:, , point at 1, to, , bridge., , Ans. (A) 1 N, , 2 0 and R are connected in series, resistance R' 2+ R, , Ans. (D), , resistance S to be 100 2. He finds the null, , (B) He should change S to 3 Q and repeat the, experiment., (C) He should change S to 1000 and repeat, the experiment., (D) He should give up hope of a more, accurate measurement with a meter, , Explanation:, a, , 4, , 10. A resistance R is to be measured, using a, meter bridge. Student chooses the standard, , following is a useful way ?, (A) He should measure i more, , Ans. (B) Mobility, , 5. The element of, , Current Electricity, , (A) 15 2, , (B) 162, , (C) 17, , (D) 18, , in, , terms of, , (CaSE 2020 set 55/2/1), , A), , (B), , C)em, , (D) None of these, , Ans. (A), , m, , Mobility is defined as the, Explanation:, unit electric, of dritt, magnitude, , field., , velocity per

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vIDYA maKmarks, 52, , PHYSIcs, , | CLAss, , 12, , 50, , 300X9 1.50, =, , Given va =, , car, , m, , Hence, =, , m, , have their, 15. If two electric bulbs P and Q, are, resistance in the ratio of 1 : 2. They, , battery., ratio of the power dissipation in, , connected in series, the, , bulbs is:, , across, , a, , Then, these, , B) 1:2, D) 2:2, , 2:1, () 1:1, , (A), , an, , (A) 30 A, , D) 34 A, , (C) 32 A, , Ans. (A) 30 A, , Explanation:, E.m.f., E, Internal resistance,, , r, , Explanation:, , Scan Yourself, 21. The capacity of a storage cell is expressed in:, , 12 V, , =0.4 2, , Ans. (C) electric energy from chemical energy, 23. Which of the following is NOT the name of, a secondary cell?, , Ans. (C) Fuel cell, , 19. A negligibly small current is passed through, , 24. What, cell?, , (C), , (D) 1.8 V, , 3, , x, , 10Q-m, , (B) 2x 10N-m, , (D), , 4, , x, , of the following is NOT the, disadvantage of polarisation of voltaic cell?, (A) Increase in internal resistance, , Ans. (B) 2 x 107 Q-m, , Ans. (C) 1.7v, , (B) Wastage of chemical energy, (C) Setting up of back emf, , Explanation, Givenl=15 m,, , Explanation:, EME E= Ep+Eaj, EME E + 2, , (D) Decrease in current supply, , A = 6 X 10, , m, , R, , 0-2+0:3, , 0-45+04, , transported by:, RXA, , 0-5, , 1.7 V, 17. In a potentiometer arrangement for determining the emf of a cell, the balance point, of the cell in open circuit is 350 cm. When, , P, , =, , a resistance of 9, , Ans. (B) Wastage of chemical energy, is, 26. Within the electric cell, the charge, , R 5Q, , 1:5X03+2x02, , is used in the external, , circuit of the cell, the balance point shift to, 300 cm. The internal resistance of the cell is, (A) 15Q, , (B) 1.5, , (C)0.152, , (D) None of these, , Ans. (C) 0.15 2, , If three resistors 1 ,, , 2 N, , and 3 N, , r- (1)n-(, , are, , ofthe, , (D) None of these, , C), , R, , (A) Daniel cell, , (B) Dry cell, , (C) Acid cell, , (D) Fuel cell, , of acid, 28. The relative density of the electrolyte, to fall, should not be allowed, , R1 + R2 + R3, = 1 + 2 +3, , r=, , 300, , x90, , = 62, , For Detailed Solutions Scan, , resistivity of a material is inversely, proportional to:, (A) number density of electrons as well as, relaxation time, (B) number density of electrons and directly, proportional to relaxatiorn time, , (C) relaxation time and directly proportional, to the number density of electrons, , neither relaxation time nor number, density of electrons, Ans. (A) number density of electrons as well a, relaxation time, , D), , 30. For ohmic conductoz, the drift velocity va, and the electric field E applied across it are, , related as:, , (A) D VE, , (B) E, , (C) E3/2, , (D) va E, , 31. What c a u s e s lower efficiency of alkali cell as, compared to the acid cell?, (A) Lower emt, , (B) Small amount of electrolyte, (C) Longer life, (D) Higher internal resistance, Ans. (D) Higher internal resistance, 32. Which of the following is NOT the, , common, , name of storage cells?, (B) Nife cell, (A) Edison cell, , (D) Plante cell, , (C) Acid cell, , Ans. (D) Plante cell, 33. Why, , we, , prefer constantan, , (C) High, , (D) both +ve and -ve, Ans. (D) both +ve and -ve ions, more likely, 27. Which of the following cells is, to be damaged due to short circuiting?, , accumulator, below:, , 29. The, , wire for, , making, , (B) High resistivity, ions, , Ans. (C) Acid cell, , Ans. (B) 6, , (D)1.18, , (A) Low resistivity, , ions, , (C) only-ve ions, , combined in series. Then the total resistance, combination is, (B) 62, (A) 52, , Explanation:, Total resistance,, , Explanation, , (B) only, , +ve, , (C) 1.28, , standard resistors?, , (A) free electrons, , 5x6x10", 15, , 2 x 10 2m, 20., , (A) Voltage increases, , 25. Which, , 10-m, , (B) 1.50, , Ans. (B) v «E, , (B) Energy given out, (C) Relative density of electrolyte decreases, (D) Cathode becomes chocolate brown, Ans., , (A) 1x107Q-m, , (B) 1.6 V, , the charging of acid, , is, , measured to be 52. The resistivity of the, material at the temperature of the experiment, is:, , happens during, , (A) Voltage increases, , wire of length 15 m and uniform crosssection 6.0x 10 m and its resistance is, a, , (A) 1.5 V, C) 7 V, , (B) Alkali cell, (D) Storage cell, , (C) Fuel cel, , I-04 30A, , the emf is:, , (D) none of these, , (A) Acid cell, , are connected in series:, , respectively, , (C) farad, , Then, according to Ohm's law,, , The current in the two bulbs, is same as they, , having, , (B) ampere-hour, , battery be I., P, , and 2.0 V, internal resistances 0.2 N and 0.3 2, Then, a r e connected in parallel., , (A) ampere, , Ans. (B) ampere-hour, 22. The electric cell is a device to obtain:, (A) electrons, , E = I, , 16. If two cells of emf's 1.5 V, , 53, (A) 1.80, Ans. (D) 1.18, , (B) electric charge, (C) electric energy from chemical energy, D) electric force, , drawn from the, Let the maximum current, , Ans. (B) 1:2, , Power,, , has, , emf of, of a, 18. The storage battery, of the battery, 12 V. If the internal resistance, can, is 0.4 2.Then, the maximum currentthat, is:, be drawn from the battery, (B) 25 A, , E, , Current Electricity, , temperature, , coefficient, , f, , resistance, , coefficient of resistance, , (D) Low temperature, coefficient of resistance, Ans. (D) Low temperature, so as, 34. A number of cells, , are, , to be grouped, The internal, , current., , to obtain maximum, resistance of each cell is, R., external resistance is, , r, , and the total, Which of the, , following is wrong?, c o m b i n a t i o n for R> r, (A) Series, forrR<r, , and parallel

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54, , vIDYA MaKmarks, , PHYSIcs | CLASs 12, (B) Parallel, , decreases, , combination, , for R>, , r, , and series, , forR<r, , (C) Mixed combination for R, (D) None of the above, Ans. (B) Parallel combination for R, , r, , >, , Ans. (C) The emf, below in which case the, 40. In the circuit given, not change when R, is, ammeter reading will, varied ?, , r, , Current Electricity, , 55, , 47. The colour coded resistance of carbon, resistor of fig. (Initial three band are red and, fourth band is silver):, , will be nearest to, , +, , and series, , RED SILVER, , (B) R1= 2r, , (A) R=r, (C) R> Ra, , (A) more than 2V, , B) 2V, , (C) 1.8 V, , (D) none of these, , Ans., , (D) r=0, , Ans. (D) r=0, , 41. Which of the following is NOT the active, , Ans. (C) 18 V, , 36. Given that R= 2 2, R 3 Q and Rs 62, Which of the following combinations will, =, , =, , give an effective resistance of4N?, (A) All in parallel, (B) R and R2 in parallel in series with R3, , material in lead storage cell ?, , (A) Lead peroxide, , (B) Lead sulphate, , (C) Sponge lead, , (D) Sulphuric acid, , Ans. (B) Lead sulphate, 42. Which of the following is one of the active, , (C) R2 and Rg in parallel in series with R, Ans. (C) R2 and Rg in parallel in series with R, , 37. Below we show our V-Igraphs, , (B) 2200 2 t 10%, , (C) 333 2 t5%, , (D) 33000 SQt 109%, , (v), , (C) (ii), , (B)(i), , Ans. (C) (ii), 38. Find the resistance across A and B in the, circuit given below:, , (B) R>r, , (C) R<r, , D) R=r, , G, , (B) Potassium oxide, , (C) Iron oxide, , (D) None of these, , (A) e.m.f., , (B) potential, , (C) resistance, , (D) current, , 32, , 44. Two unequal resistors are connected, , in, , 50 D, , B, , across, , (C) Depends, cell, (D) Depends, , either resistor is, , same, , (B) Potential drop across smaller resistor is, , 45. A, , above, , can be, , Ans. (B) D to B, 50. Two unequal, , battery is made by connecting 4, , cells, , (D) 6, , (A) 20 Ah at 6 V, , (A), (B), (C), (D), , Relative density, , of, , of, , electrolyte decreases, change, The emf decreases, , The emf does not, , Relative density increases, , C)5 Ah, , at 6V, , (B) 20 Ah at 1.5 V, , (D)5 Ah at 1.5 V, , Ans. (C) 5 Ah at 6 V, 46. An external resistance R is connected to a, cell of internal resistance r. The current n, the circuit is maximum when:, (A) R>r (B) R<r (C) R= r (D) R = 0, Ans. (D) R =0, , of the, , the internal resistance, , (r), , of, , An's., , 9SE, , 62, , (A)3, , (B), , (C) 92, , (D) 122, , Ans., , (D) 122, 55. The resistance of hot tungsten filament is, about 10 times the cold resistance. What will, , be the resistance of 100 W and 200V lamp, when not in use ?, , resistances, , are, , connected in, Ans., , resistors, (A) Same current is set up in both, Current through smaller resistor is more, , in, , (C) 9.1, , discharging, , (E), , parallel across a cell. Which of the following, , true, , 5eries each having capacity 5 Ah at 1.5 volt., The battery will have capacity equal to, , the, , on, , the value of emf, , statements is true ?, of the, , (B) 72, , during, , (B) D to B, on, , the cell, , (A) 5A, Ans. (C) 9.10, 39. What happens, Edison cell ?, , www.r102, , (A) B to DD, , series with a cell. Which of the following, , 62, www, 22, , m, , more, , 2, , ww., , A1, , depending on the emf of the cell, Ans. (C) Potential drop across larger resistor 15, , 403 752, , circuit given below, , (C) R<r, , Ans. (C) resistance, , (D) Any one, , (C) smaller than the smallest resistance, , 54. Find the resistance between A and B in the, , 1052r, , more, , 50, , Ans., , 92, , (C) Potential drop across larger resistor is, , A, , (C) smaller than the smallest resistance, (D) larger than the smallest resistance, , www, , more, , A, , (B) larger than the largest resistance, , conventional current between B and D?, , (A) Nickel oxide, , statement is true ?, (A) Potential drop, , (D) R = 0, , (A) smaller than the largest resistance, , (A) R= o, , 43. Wheatstone bridge is used to measure, , A) ), , (B) R>r, , (C) R=r, , 53. The equivalent resistance of the parallel, combination is, , (B) 2200 2 + 100%, , Ans. (D) None of these, , (iv), (i), (ii), Which is the V- I graph for semiconductor, diode, , (A) R<r, , 49. Figure, below, shows, an, unbalanced, wheatstone bridge. What is the direction of, , materials of the Edison cell ?, , (D) R3 and R, in parallel in series with R2, , the absence of, , Ans. (B) R>r, , (A) 222 2+ 10%, , 48. An ammeter of resistance R is to be used to, measure the current through a resistance r., In which case the reading will be nearest to, the current in the absence of ammeter., , Ans., , difference, the reading, , that in, , voltmeter?, , for R<r, , N and, 35. The internal resistance of cell is 0.1, its emf is 2V. When a current of 2A is being, drawn from it the potential difference, across its terminals will be:, , 52. A voltmeter of resistance R is to be used, to measure the potential, across, a resistance r. In which case, , (B), more, (C) Current through larger resistor is, true, of, the, one, be, above can, (D) Any, cell, depending on the emí of the, is more, (B) Current through smaller resistor, , (A) 14000 Q, , (B) 400 2, , (C) 402, , (D) 4, , (C) 40 2, , 56. In the circuit given below, the ammeter, reading is zero. What is the value of the, , resistance R?, 12V, , 1. The resistance of 1 kg of a material in the, What will be, , side l is R., cubical form of each same, material is used as, , 5000, , the resistance, if the, , a rectangular block of length 21?, , (B) 2, , (C), , 2R, , Ans. (D) 4R, , (A) 50 2, , (B) 100, , (C) 200 2, , (D) 400 2, , (D) 4R, Ans. (B) 100 2

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56, , VIDYA MaDKmarks, , PHYSIcs | CLASs 12, , 62. What is the total resistance of the, 57. You are given three equal resistors. How, many groups of resistances can be obtained, by joining them in series and parallel, grouping?, (B) Three, A) Two, (D) Six, (D) Four, , shown in fig:, , 50, , wwwM, , 52, , ww, (A) 0.25 A, , B) 0.5 A, , (C) 1.0A, , (D) 2.0 A, , Ans. (D) 2.0 A, 59. The equivalent resistance in series, combination is:, (A) smaller than the largest resistance, (B) larger than the largest resistance, the smallest resistance, (D) larger than the smallest resistance, Ans. (B) larger than the largest resistance, 60. What is the current through the 32, resistance in the circuit shown below?, , (C)smallerthan, , E 5V, , E, , 3A, wwww, , 20, 5A, , w.T, , (B) nE, , (C) E/n, , (D) None of these, , 72., , In the circuit shown below, what is the, , potential difference across A andB?, 60V, , 202, , H, , 5v,,32, , (A) 62, , (B) 7, , (C)8, , (D) 9, , Ans. (C) 8Q, 63. Potentiometer is better for measuring the, potential difference than the voltmeter, because:, (A) it uses a long wire, (B) it uses an auiliary battery of large emí, (C) it does not disturb the potential difference, to be measured, , 402, , 2V,, , (B) 2A, (D) 0.5 A, , (C) 1A, Ans., , (A) 60 V, (B) 45 V, (C) 30V, (D) 20 V, Ans. (A) 600V, 73. Which of the following is true when the, , 12, , (A) 4A, , cells are connected in series ?, , (C) 1A, , 68. Four resistors are connected as shown, and, a 6 volt dc battery of negligible resistance, is connected across terminal A, C. The, , potential, , (D) itisbased on the principle of Wheatstone, , difference, , across, , terminal B, D, , will be:, , bridge, , 6V, , Ans. (C) it does not disturb the potential difference, to be measured, 64. Gy G, G3 are the conductances of three, they are joined in series,, their equivalent conductance will be:, , (A) Current capacity increases, (B) Current capacity decreases, (C) The emf increases, D) The emf decreases, Ans. (C) The emf increases, 74. Two identical batteries are connected in, series with + ve terminals together, ve, terminals together, forming a closed circuit, , and, , ~, , Which of the following will be zero?, , (A) The emf of each cell, , conductors. When, , 52, , 30, , 102, , (B) Potential difference across each cell, , (A) G+G2+G3, , (C) Current in the circuit, , D) Resistance in the circuit, , (B), , (A) OV, (C) 2V, , GGG2G3, , (G+G+G, , Ans. (D) given by some other relation, 65. In the fig. the, potential difference across AB, is 3V. If the internal resistance of the, battery, is 12, its, emf is, , (B) 1.5V, (D) 3V, , 12, , 40, , 60, , (A) Tungsten, (B) Carbon, , 72, , (C)Auxiliarybattery only, (D) Neither cell nor auxiliary battery, , (A)6V, (C) 15 V, Ans. (B) 9 v, , resistances ?, , (A), (B), (C), (D), , (B) 1.52, , (C) 2.0, , (D) 2.5, , ideal cells are connected in parallel ?, (A) Current capacity increases, (B) Current capacity decreases, , It is based, It does, It is, , a, , on, , not, , arms, , Kirchoff's lawvs, , involve ohm's law, , null method, , 76. Slide wire bridge does not operate, , on, , the, , same principle as the:, (A) Wheatstone bridge, (B) Potentiometer, , through, , (A) 1.02, , It has four resistor, , Ans. (D) It is a null method, , (C), (D), , internal resistance of the cel1?, , 1. Which of the following is true when the, , (B) 9V, (D) 18V, , than the other methods of measuring, , A cell supplies a current of 1A through, A, resistance of 50 and a current of 0.6, resistance of 10 Q. What is the, a, , Ans. (D) 2.5 N, , www, , 75. Why the Wheatstone bridge is more accurate, , (B) Cell only, , 70., wwww., , Ans. (C) Current in the circuit, , Ans. (A) 0V, 69. When the balance point is obtained in the, potentiometer, the current is drawn from:, (A) Both the cell and auxiliary battery, , Ans. (C) Auxiliary battery only, , the, , (D) Platinum, Ans. (B) Carbon, , (A) nE, , below?, , (B) 3A, (C) 11 A, (D) Cannot be calculated unless E2 is known, Ans. (A) 5 A, 61. Which of, following has ve temperature, coefficient of resistance?, , (C) Nichrome, , (C) The emf increases, , Ans. (D) None of these, 67. What is the current in the circuit given, , 22, , 4, , (D) given by some other relation, , www., , A), , w, , 57, , (D) The emf decreases, Ans. (A) Current, capacity increases, , is:, , ww, , wwww, , 44, , 66. If n cells each of emf E are connected in, parallel, the effective emf of the combination, , V, , 3, , wwww.., , current Electricity, , wwww, , Ans. (D) Four, 58. What is the reading of ammeter in the, fig.? Assume that the internal resistance of, battery is zero and the key is closed ?, 10V, , ircuit, , Ans., , Post office box, None of the above, , (B) Pbtentiometer, , Kirchhoff's law, the sum, 77. According to the, current and resistance as, of, the, of, products, closed, a, in, emf's, loop is:, well as, than z e r o, (A) greater, (B) zero

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VIDYA, , 58 PHYSIcs | CLASS 12, , mark curent Electricity, , 82. The null point in a potentiometer with, obtained at a distance' 'T, of e.m.f. Eis, on, t, , (C) less than zero, (D) determined by the emf., , wire. Then:, , Ans. (B) zero, 78. In the circuit given below, the ammeter and, , voltmeter are ideal measuring devices. What, is the reading of the voltmeter ?, 6V, , (B) EP, , (A) Ex1, , L, , Ans. (A) E« 1, , 83. Out of the following which does not pos,, oSses, negative temperature coefficient?, (B) Rubber, (A) Paper, , 129, (A), , 6V, (C) 1.5 V, , (B), , with a cell is at length 240 cm. On, shunting, the cell with a resistance of 2, the, , 4V, , (D) 05, , drop, , inside, , the, , battery, , increases, (B) emf of the battery decreases, , (C), , internal, , resistance, , of, , the, , increases, , potential, , drop, , inside, , increases, , the, , (C)0.75V, , (D) 1.00 V, , bulbs, , identical. How do the, of the bulbs compare?, are, , battery, , Ans. (C)17, , (C) 2 ohms, , (A) 0.5 2, , (B) 1.02, , (C) 2.02, , (D) 4.02, , (C) 2, Ans. (A), , 4, , a, , die, , www, , the wire will be :, , (B), (D) 4, , (0), , (C) 4 R, , (D) 16 R, , oversight, , the emf and internal, combination will be, , resistance, , (A) 7E, 7, , (B) 5E, 5 r, , (C) 7E, 5r, , (D) 5E,7, , of, , the, , wW-, , Two wires have, , same, , length., , (C), , R, , (D) 3R, , Ans. (C)R, conductor decrease, a, 96. The conductivity of, because on heating:, with temperature, , (A) atoms vibrate vigorously, (B) conductor expands, (C) electrons gain energy, , Ans. (D) 5E, 7 r, , other. If the, , W, , (B) R, , (A), , internal resistance, 91. 7 cells each of emf E and, series. If due to, in, connected, r are to be, one cell is connected wrongly, , cross-section, , A and B in the, , www.-, , Ans. (C) 4 R, , ., , across, , www., , so as to double its length. If the original, resistance of, resistance be R, then the new, , R, (A) 16, , B) 1 ohmn, (D) 5 ohms, , Ans. (B) 1 ohm, 95. What is the resistance, fig. ?, , 90. An aluminium wire is drawn through, , 86. Whena, current I is set up ina wire of radius, r, the drift speed is, va If the same current b, set up, through a wire of radius 2r the dril, speed will be, , (A), , piece, , (A) 8 ohms, , ofthe cel1?, , brightest, brightest, , None of these, , resistance is, , Ans. (A) 0.5, , Le, , (D), , of wire of resistance 4 ohm is bent, through 180° at its mid-point and the two, halves are twisted together. Then, the, , 94. A, , current of 4A. What is the internal resistance, , brightnesses, , (B) E/R, , Ans. (B) E/R, (B) 122, (D) None of these, , (C) 15Q, , 85. In the circuit in figure given below, all fou, , battery, , (A) E/2R, (C) 2 E/3R, , Ans. (D) None of these, 89. A cell of emf 2V, when short circuited gives a, , (C) Bulbs 1 and 4 are brighter than 2 and 3, (D) Bulbs 3 and 4 are brighter than 1 and 2, Ans. (C) Bulbs 1 and 4 are, brighter than 2 ands, , 14R, , ww, , w., (B) 0.66 VV, , Bulb 1 is, (B) Bulb 4 is, , 14R, (C)7, , B, , R, www-, , (A) 0.25 V, , (A), , (B) R, , A, , (A) 92, , the circuit given below?, , (A) 2R, , and B in the fig, if R = 32?, , 50cm, , 81. What is the total resistance across A and B in, , w-, , Ans. D)1 and 5, , 82, www., , Ans. (B) 0.66 V, , (D) current drawn from the battery decreases, Ans. (A), , (C) 3 and 4, , is the current through the resistor R in, What, the circuit shown in fig. The emf of each cell, , 12, , Ans. (B) 20, 80. When the car starts, the illuminance of the, head lights decreases. This happens because, the, , (A) potential, , (D) 12.5 2, , s E., , (B) 2 only, (D) 1 and 5, , www-, , internal resistance of the cell isS:, (A) 42, (B) 20, 19, , 93., , shown in fig, if the deflection in th, galvanometer is zero ? The resistance of th, wire is 3 2. The length of the wire is 100 cn, , balancing length becomes 120 cm. The, , (B) 50 2, , (C) 25 Q, , Ans. (B) 502, , (A) 1 onlyy, , 84. What is the emf of the cell C in the ciru, , (D) Zero, , (A) 100 2, , 88. What is the equivalent resistance across A, , Ans. (D) Nichrome, , 3V, , Ans. (D) Zero, 79. In a potentiometer experiment the balancing, , (C), , (D) Nichrome, , C) Gutta Parcha, , what is the resistance of the thicker, 2002,, wire?, , Which bulb(s) light{s) most brightly?, , ) E, , (C)E, , 59, , 87. All bulbs in figure below are identical., , But, , area, , of, , that of the, of o n e is 4 times, wire be, resistance of thinner, , (D), Ans., , (C), , electrons vibrate vigorously, electrons, , gain energy

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VIDYA MaKmark: curent Electricity, , 60 PHYSIcs CLASS12, the potentiometer wire, N. The, force of 2.4 x, wire is 4 m. The, of, potentiometer, length, emf of the battery connected across the wire, , 97. An, , electron, , experiences, , in, , the, , (B) 4.0 V, , (C) 4.8V, , (D) 6.0 V, , 10 ohms each are connected in the formof, , (A) 5E, , quare. The equivalent resistance between, , Ans. (C) 3E, , and, , (A) 10 ohms, , (B) 40 ohms, , C) 20 ohms, , (D) 10/4 ohms, , Ans. (A) 10 ohms, , across the battery. The internal resistance of, , have equivalent resistance of 3 2. When one, , the battery is r = 1.5 2., , of the resistance is burnt and broken, the net, resistance is 12 2. What is the resistance of, the burnt resistor ?, (A) 4, (B) 82, (D) 162, , ()122, www-, , (A) 4, , 104. In apotentiometer experiment for measuring, the emf of a cell, the null point is at 240 cm, when we have a 5002 resistor in series, with the cell and galvanometer. If the series, resistance is reduced to half, the null point, , ww., reading in the ammeter?, B) 1.5 A, (A) 1A, (, 10.5 A, (D) 12 A, Ans. (A) 1A, 99. In a potentiometer of 10 wires, the balance, is obtained on the 6th wire. To shift the, balance point to 8th wire, we should, (A) increase resistance in the main ircuit, B) decrease resistance in the main circuit, , point, , (A) 480 cm, (C) 120 cm, , Ans. (B) 240 cm, 105. A cell of emf E is connected across a, resistance R. The potential difference across, of, is V. What is the, internal resistance of the cell ?, , the terminals, , the cell, , Ans. (A) increase resistance in the, main circuit, 100. Five cells each of internal resistance 0.2 2, and e.m.f. 2V are connected in series with a, , resistance of 4 2 The current through the, external resistance is:, , analyzing, , an, , electric, , (A) Einstein's theory (B) Newton's laws, (C) Kirchhoff's laws (D) Faraday's laws, Ans. (C) Kirchhoff's laws, , (C)1A, , (D) 2A, , 107. Kirchhoff's first and second laws, , between, , wo, , points separated by, , potential, , 50 cm, , on, , of, , (A) momentum and energy, (B) charge and energy, (C) mass and energy, (D) none of the above, Ans. (B) charge and, energy, , Resistivity, , (8) inversely proportional to temperature, (C) independent of dimensioins of conductor, , (D) finite and its value increases with, increase of time of use, , and, , its, , value increases with, , increase of time of use, , (D) less than resistivity of a semiconductor, Ans. (A) independent of temperature, 117. Which material is expected to have least, (Diksha), resistivily?n, , (A) Copper, (C) Mercury, Ans. (A) Copper, , of the cell must bee, (A) E, , (B) E/2, , (C) E/4, , (D) 3E/2, , (Diksha), , (B) Lead, , (D) Zinc, , make it, , 118. A copper wire is stretched to, 0.2%. What is the percentage change in its, (Diksha), , resistivity?, , T is connected across a resistance R. The, potential difference between the terminals, , (A) 04%, , (B) 2.07%, , (C) 4.0%, , (D) None of these, , Ans. (D) None of these, 119. The V-I characteristics shown in figure, , represents, , Ans. (B) E/2, 112. Four resistors, , (all having, , resistance, , 5), , Re=5 2, (A) Sum all, (B) One in parallel to sum of three, (C) Two in series are parallel to other two in, series, (D) Two in parallel to series of other two, Ans., 113., , are, , respectively based on law of conservation, , battery of 6 volt is connected to the, terminals of the 3 meter, long wire of, uniform thickness and, resistance of the, order of 100 ohm. The, difference of, , increases5, Ans. (D) Resistivity of Cu decreases and Ge, increases, 116. Which of the, following is wrong?, of a conductor is, (Diksha), , (D) 1.1, , increase of time of use, , (Diksha), , (B) 0.5 A, , Ans. (D) 2A, , () Resistivity of Cu decreases and Ge, , should be connected in which way to obtain, , A) 0.2A, , 101. A, , and, , (Diksha), , (A) independent of temperature, , 110. About internal resistance of a cel, the, correct statement is that, it is, (Diksha), (A) constant for a given cell, (B) infinite, (C) finite and its value decreases with, , (D)ER, , 106. The basic laws for, circuit are, , (Dksha), , (C) 0.122, , (A) E-, , Ans., , taken, , (C) Resistivity of Cu increases and Ge, , Ans. (B) 02, , () increase resistance in series with the cell, whose emf is to be measured, (D) decrease resistance in series with the cell, whose emf is to be measured, , (Diksha), , 111. A cell of e.m.f. E and internal resistance, , (B) 240 cm, (D) 60 cm, , are, , (A) Resistivity of both increases, (B) Resistivity of both decreases, , D) 4 E, , (B) 0, , (A) 0.11 N, , Ans. (D) finite, , of Ge and Cu, , decreases, , cell i, , will be at, , If at any instant R1+R2 = 10.5 Q, what is the, , (C) 3E, , 109. Three identical cells, each of4V and internal, resistance r, are connected in series to a, 6 ohm resistor. If the current flowing in the, circuit is 2 A. The internal resistance of each, , 103. Two resistances when connected in parallel, , Ans., , (B) 2 E, , Identical piece, , cooled, then, , and internal resistance of the combination, , Ans. (A) 1 volt, , two opposite corners of the square is, , Ans. (D) 6.0V, 98. Fig. shows a battery B of emf12 V connected, in series with an ammeter, a resistor R, a rheostat Rz. A voltmeter is also connected, , 61, 115., , is connected wrongly. The equivalent emf, , 102. Four wires of equal length and of resis tance, , is, (A) 2.4 V, , (D) 3 volt, , C) 2 volt, , 101, , a, , 408. Five cells each of emf E and resistance r are, connected in series, due to oversight one cell, , (B) 1.5 volt, , (A) 1 volt, , (DIksha), , (C) Two in series are parallel to other two in, , series, , (A) Ohmic conductors, , A current of 2 A flows in a wire offering a, , (B) Non-ohmic conductors, , resistance of 10 ohm. Calculate the energy, dissipated by the wire in 0.5 hour (Diksha), (B) 72 kJ, (A) 72 Wh, , (C) Insulators, , (C) 7200J, , (D) 72 kJh, , Ans. (B) 72kJ, , (D) Superconductors, , Ans. (B) Non-ohmic conductors, 120. Ohm's law fails in, (A) Diode, , 14. A bulb has a power of 200 W. What is the, minutes? (Diksha), , energy dissipated by it in 5, (B) 1000, (A) 60J, (C) 60 kJ, Ans. (C) 60k), , (D) 1k, , Ans., , (B) Thyristor, (C) p-n junction system, D) All of the above, above, (D) All of the, , (Diksha)

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62 PHYSIcs |, , CLASS, , VIDYA, , 12, , varies, , with the, , 121. Drift velocity va, relation, electric field as per the, , intensity of, (Diksha), , (A) * E, (C) D= Constant, , Ans. (A) a, , (D), , E, , 122. Which of the following, the, of electrons determines, , characteristics, , (A), (B), (C), (D), , drift velocity alone, thermal velocity alone, , velocity and thermal, , Ans. (A) drift veloity alone, 123. Ohm's law is not applicable to, (A) dc circuits, (C) small resistors, Ans., , more, , (Diksha), sensitive, , Ans, (A) Both Assertion and Reason are true and, Reason is the correct explanation of Assertion, , voltmeter, , take, , where p is resistivity of material which does, does, , not, , take, , not depend on the dimensions of wire. Since,, when wire had bent its resistivity, length, and area of cross-section do not change., , current, , constant, , to, , balance point, 130. With a certain cell, the, is obtained at 65 cm from the end of a, cell whose, potentiometer wire. With another, first, the, that, of, from, by 0.1 V, the, emf differs, balance point is obtained at 60 cm. Then, the, (Diksha), emf of each cell is, (A) 1.2 V and 1.5 V respectively, , wound type, , (B) 2.1 V and 2.2 V respectively, , constant, , (D) 5.1 V and 5.2 V respectively, , (A) full deflection, , (B) partial deflection, , (C) no deflection, , (D) null deflection, , 126. In a balanced Wheatstone's network, the, resistances in arms Q and S are interchanged., (Diksha), As a result of this, (A) galvanometer and the cell must be, interchanged to balance, (B) galvanometer shows z e r o deflection, (C) network is not balanced, (D) network is still balanced, , same, therefore, , Ans. (C) network is not balanced, (Diksha), , brightness than 100 W bulbs., Reason: A 100 W bulb has more resistance, than a200W bulb., , (B) Kirchhoff's voltage law, (C) Balance Wheatstone bridge, , Ans. (A) Both Assertion and Reason are true and, , (D) Both (a) and (b), Ans. (C) Balance Wheatstone, bridge, 128. Theresistance in left and right gap of a meter, bridge are 20 2 and 30 Q respectively. When, the resistance in the left gap is reduced to, half its value, the balance points shifts, by, (DIksha), , Heat produced is hig, , melting point, , Reason is the correct explanation of Assertion, , if R is high. The, , must be low, , so, , that wire may, As the, , 4. Assertion Kirchhoff's junction, from conservation of charge., follows from, Reason: Kirchhoff's loop rule, the conservation of momentum., Ans. (C) Assertion is, , true, , but Reason is false, , connected, , Keason, , :, , in series with, , As resistance increase,, , a, , galvacurrent, , through the circuit increases, , R, , Ans., , (C), , high, , bridge experiment a, series, always connected in, , meter, , reistance is, , is, , Assertion, , Explanation, galvanometer, , true, , is false, Assertion is true but Reason, , but Reason is false, , The, , resistance, , of the, , In meter bridge, the galvanometer, experiments, to protect, resistance is, from a high current high, it from, to, order, protect, in, it, to, connected, fixed., , is, , damage, Case/Source, , Based Type, , 1 Mark, resistance, , resistorwhose, 1. Athermistorisa type of, temperature,, on, dependent, is strongly, than, , in, , Thermistors are, , The word, and resistor, , standard resistor., , combination, , . Assertion: In meter bridge, a high resistance, always, nometer., , 8. Assertion In, , more, , rule follows, Explanation: Kirchhoffs loop, conservation of ener8y, 15, , the, be dissipated without overheating, device, when this rating is exceeded, heat, , Ans. (C), , rule follows, , -, , y2, , Because of heat production, , with a galvanometer, Reason: As resistance increases, the current is, more accurately measured by galvanometer, , through the fuse wire,, break the circuit., , Explanation: As we know that,, P=, , remains, , law,, , melt with increase in temperature., safe value, flows, current equal to maximum, it heats up, melts and, , Reason is the correct explanation of Assertion, but, (B) Both Assertion and Reason are true, Reason is not the correct explanation of, , 1. Assertion: The 200 W bulbs glows with more, , according, , current, , to Joule's, , H= 42cal, , true and, , (C) Assertion is true but Reason is false, (D) Assertion is false but Reason true, , temperature., Ans. (D) Assertion is false but Reason true, , change unpredictably., , high, , Fuse wire must have, , :, , resistance because in series, , Assertion, , 7. Assertion: In practical application, power, rating of resistance is not important., Reason: Property of resistance depends on, , is produced, due to which resistance may, , below., are, , 1S, , only, , Assertion-Reasoning Type 1Mark, (A) Both Assertion and Reason, , substance, , every resistances has a maximum power, rating the maximum power that can, , Select the correct answer to these questions, from the codes (A), (B), (C) and (D) as given, , Ans. (D) null deflection, , a, , 1ts resistance when it is one metre long and, its area of, cross-section is one square metre., Reason: The SI units of resistivity is ohmn, meter., Ans. (B) Both Assertion and Reason are true, but, is not the correct explanation of, , Fuse wire must have high, resistance and low melting point., Reason: Fuse is used for small current flow, , Assertion, , Explanation, , Ans. (C) 1.3 V and 1.2 V respectively, , galvanometer., Assertion: The resistivity for, , Explanation:, , same., , Ans. (C) Assertion is true but Reason is false, , C) 1.3 V and 1.2 V respectively, , 125. Wheatstone bridge works on the principle, (Diksha), of, , Therefore, resistance of wire also remains, , 3., , ., , Explanation:As, R=A, , R=P, , curren, , from the circuit, , Ohm's law, 124. The condition for the validity of, (Diksha), is that the, remain, (A) Temperature should, be, should, Current, proportional, (B), , (D) potentiometer, , bridge, protect the galvanometer expermentd, from tong, current, high resistance is connected, the, , Reason, Assertion, , Explanation: Resistance of a wire, than, , Ans., , (D) semi-conductors, , 127. Meter bridge is application of, (A) Kirchhoff's current law, , than, , of potentiometer is less, , (C) potentiometer is cheaper, not, (D) potentiometer does, , (Diksha), , D) semi-conductors, , C) Resistance must be wire, (D) All of the above, Ans. (A) Temperature should remain, , Reason: Resistance of wire is proportional to, resistivity of material., , from the circuit, , (B) high currents, , voltage, , is, , than voltmeter, , velocity, neither drift nor thermal velocity, both drift, , voltmete;,, , because, , (Diksha), , conductor?, , over, , electrical resistance., , meter, , to, , brightly, Assertion: Bendin8 a wire does not effect, , a, , S, , lesser is the resistance and so it will gloww, , of potential difference,, , (A) potentiometer, voltmeter, (B) the resistance, , :The, Explanation, resistanceof galvanometer, fixed. In, , That means higher is the wattage of a bulb,, , 129. For, potentiometer is preferred, , ina, , current, , 63, , R, , (A) 15 cm to the right, left, (B) 15 cm to the, the, right, (C) 20 cm to, left, (D) 20 cm to the, Ans. (B) 15 cm to the left, measurement, , « E, , Max marks curent Electricity, , of, , thermal, , widely used, , as, , in rush current, , sensors,, , limiters, temperature, protectors, over current, elements., , self-resetting, regulating, are generally, , and self, , Thermistors, , heating, metal oxides,, powdered, produced using, or cylindrical shape, a bead, disk, into, pressed, with an impermeable, encapsulated, and then, o r glass., such as epoxy, material

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64, , PHYSIcs, , | CLASS, , VIDYA MaKmark, , 12, , The energy liberated in 20 minutes, W =Pxt, 25 x 20x 60, = 3 x 10J, , (iv), , Nichrome and copper wires of, , same, , current Electricity, , ), lengt, , and same radius are connected in series and, them. Then:, current passed through, Nichrome wire wil be heated more, , (A), heated more, (B) Copper wire will be, , If the coil, , of, , a, , Explanation, , D), , (0 Change in resistance, measured using a ., , in, , thermistor, , (A) Anderson's bridge, , (C) Hay's bridge, , per meter, (B) 10 per meter, (C) 10 per meter, , (A), , (D) Maxwell's bridge, Ans. (B) Wheatstone's bridge, , Explanation : The change in resistance in a, thermistor is measured using a Wheatstone's, bridge. It is used for measurement of, , Ans., , resistance between the range of - 100°C to, , (B) Increases, D) Doubles, , Ans. (B) Increases, , Explanation: By increase in temperature, the, , (Hi) An electric bulb was marked 100 W-230 V., If the supply voltage drops to 115 V, what, be the total energy liberated in form of, heat and light by bulb in 20 minutes ?, (A) 3.8 x 100j, (B) 3 x 10J, , will, , (D) 4.5 x 10 J, , C)6x10J, x, , 10J, , Then,, If the, Then, , (iv) The resistance of conductor depends upon:, (A) Cross sectional area, (B) length of wire, , (C)10 permeter, , (A) V/R, (C) PR, Ans. (B) P/R, , (B) P/R, (D) VI, , The process in, move from a higher potential to lowe, (A) heat energy, , (B) light energy, , voltage drops to 115 Vx, , 115x115, 529, , = V/R3 VI, which charges continuous, , potential becomes a continuous source or, , (230), =100 =529N, , PP-R, , (C) wire's nature, (D) all of the above, Ans. (D) All of the above, , Explanation: As =R(v) As compare to thin wires, thick have ., resistance, (A) more, , (B) less, (C) same, , appliances like bulb, electric iron, electri, heater etc. runs on the principle of Joule:, heating effect., () Which of the following terms does nol, represent electrical power in a circuit?, , (i), , P, , R, , Hence, resistance becomes half of initial, , Explanation: As P=/R, , Explanation:, Since,, , { wire is cut to half}, , resistance and so is heat., , i, , relaxation timer decreases orthe hindrace in, the path of electric current increases. Due to, which, the resistance of wire increases., , 10, , 2. A conductor becomes hot after some time i, an electric current is passed through it. This, phenomenon of production of heat in a, conductor by the source of an electric current, through it is called Joule's heating effect or, heating effect of current. In a purely resistive, ircuit, the energy supplied by the source, emf is completely converted into heat energ, but if the ircuit has an appliance like motor, etc. then some part of energy supplied, converted into useful work. Various electrica, , increased, what is the effect on its electrical, , Ans. (B) 3, , P2, A2, , (C) chemical energy, (D) electrical energy, , 25 W, Ans., , (D) electrical energy, , :, , (D) none of the above, Ans. (A) nature of materials, , Explanation, , (D) 10 per meter, , 200°C., (i) When the temperature of a metallic wire is, resistance?, (A) Decreases, (C) No effect, , R2, , more, , () What is the order of the number of free, electrons in metals?, , Resistivity is independent of, , (B) temperature, (C) dimensions of materials, , RNiReu, , (B) Wheatstone's bridge, , Dim ight, , (A) nature of materials, , Wire will be short-circuited, , Then,, , arnounl of, resistance, , Bright light, (), , Explanation: Since, Pu> Pau, , is, , High, , Small amount, Yof resistance, , Ans. (B) Halved, , (C) Both will be heated in the same amount, Ans. (A) Nichrome wire will be heated, , 65, , heater is cut to, half, what, would haPpen to heat produced?, (A) Doubled, (B) Halved, (C) Remains same (D) None of these, , (D) not enough information, , Ans. (B) less, , Explanation: As, Ro, 3., , Resistance is a measure of the opposition to, , flow in an electric circuit. Resistance, 1s measured in ohms. Also resistivity, the, unit, electrical resistance of a conductor of, and unit length. A, area, Cross-sectional, characteristic property of each materials,, is useful in comparing various, current, , resistivity, , materials, , on, , the basis of their ability to, , conduct electric currents., , As resistivity is the, , characteristic property of the materials., (i) For which of the following dependence of, drift velocity va on electric field E, is ohm's, law obeyed?, (B) D E2, (A) P «E, , (C) P= constant, Ans. (D) Da= E, , (D) va= E, , (11) Two resistors are said to be in ., is one, end of all resistors is joined together and, similarly the other ends joined together, refers to:, (A) Series, (B) parallel, (C) either (A) or (B) (D) None of these, , Here, A, , Ans. (B) parallel, (iv) The example of non-ohmic resistance is :, (B) copper wire, (A) diode, (D) carbon resistor, (C) filament lamp, Ans. (A) diode, (v) Nichrome or Manganin is widely used in, wire bound standard resistors because of, their:, , (A) temperature independent resistivity, (B) very weak temperature dependent, resistivity, (C) strong dependence of resistivity with, temperature, (D) mechanical strength, , Ans. (B) very weak, resistivity, , temperature, , Explanation: These materials, values would be, , dependent, resistance, , changed by very, , temperature change., , little