Current Electricity PYQs Set 2 (PDF)

Set 2 of 21 · Questions 31-60 of 612

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Mere Teacher · Previous Year Questions NEET Physics · Current Electricity · Set 2 (Q31-60)
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31. $Balancing point of a potentiometer shifts from a length of 60 cm to 40 cm by shunting the cell with a 4 ohm resistance. What is the internal resistance of the cell?$ (1) $1Ω$ (2) $2Ω$ (3) $4Ω$ (4) $6Ω$ 32. $Three resistances 2Ω, 3Ω and 4Ω are connected in parallel. The ratio of currents passing through them when a potential difference is applied across its ends will be$ (1) $6 : 4 : 3$ (2) $4 : 3 : 2$ (3) $6 : 3 : 2$ (4) $5 : 4 : 3$ 33. $As the temperature increases, the electrical resistance [NEET 2022]$ (1) $decreases for both conductors and semiconductors.$ (2) $increases for conductors but decreases for semiconductors.$ (3) $decreases for conductors but increases for semiconductors.$ (4) $increases for both conductors and semiconductors.$ 34. $A copper wire is stretched to make it 0.5 % longer. The percentage change in its electrical resistance if its volume remains unchanged is:$ (1) $2.0 %$ (2) $2.5 %$ (3) $1.0 %$ (4) $0.5 %$ 35. $A motor operating on 100 V draws a current of 1 A. If the efficiency of the motor is 91.6 %, then the loss of power in units of cal / s is$ (1) $6.2$ (2) $2$ (3) $8.4$ (4) $4$ 36. $A thermocouple of negligible resistance produces an e.m.f. of 40 µV/°C in the linear range of temperature. A galvanometer of resistance 10 ohm whose sensitivity is 1µA/div, is employed with the thermocouple. The smallest value of temperature difference that can be detected by the system will be:$ (1) $0.5°C$ (2) $1°C$ (3) $0.1°C$ (4) $0.25°C$ 37. $A milli voltmeter of 25 milli volt range is to be converted into an ammeter of 25 ampere range. The value (in ohm) of necessary shunt will be:$ (1) $0.001$ (2) $0.01$ (3) $1$ (4) $0.05$ 38. $Two metal wires of same length, same area of cross section have conductivities of their material σ_{1} and σ_{2} . If they are connected in series, the effective conductivity is$ (1) $\frac{σ _{1} σ _{2}}{σ _{1} + σ _{2}}$ (2) $\frac{2 σ _{1} σ _{2}}{σ _{1} + σ _{2}}$ (3) $\frac{σ _{1} σ _{2}}{σ _{1} - σ _{2}}$ (4) $\frac{2 σ _{1} σ _{2}}{σ _{1} - σ _{2}}$ 39. $A moving coil galvanometer of resistance 100Ω shows a full scale deflection for a current of 1 mA. The value of resistance required to convert this galvanometer into an ammeter, showing full scale deflection for a current of 5 mA, is____Ω$ (1) $0.5$ (2) $2.5$ (3) $10$ (4) $25$ 40. $Two bulbs rated 25 W 220 V and 100 W 220 V are connected in series to a 440 V supply. Then,$ (1) $100 W bulb fuses$ (2) $25 W bulb fuses$ (3) $both the bulbs fuse$ (4) $neither of the bulb fuses.$ 41. $If the masses of three wires of same material are in the ratio of 1 : 2 : 3 and their lengths are in the ratio of 3:2:1, then electrical resistances of these wires are in the ratio$ (1) $1 : 1 : 1$ (2) $1 : 2 : 3$ (3) $9 : 4 : 1$ (4) $27 : 6 : 1$ 42. $Given below are two statements: Statement I: The equivalent resistance of resistors in a series combination is smaller than least resistance used in the combination. Statement II: The resistivity of the material is independent of temperature. In the light of the above statements, choose the correct answer from the options given below:$ (1) $Both Statement I and Statement II are false$ (2) $Both Statement I and Statement II are true$ (3) $Statement I is true but Statement II is false$ (4) $Statement I is false but Statement II is true$ 43. $A galvanometer has a coil of resistance 200Ω with a full-scale deflection at 20 μA . The value of resistance to be added to use it as an ammeter of range (0 - 20) mA is;$ (1) $0.40Ω$ (2) $0.20Ω$ (3) $0.50Ω$ (4) $0.10Ω$ 44. $A potentiometer is an accurate and versatile device to make electrical measurements of EMF because the method involves$ (1) $potential gradients$ (2) $a condition of no current flow through the galvanometer$ (3) $a combination of cells, galvanometer and resistances$ (4) $cells$ 45. $In a region of uniform electric field of intensity E, an electron of mass m_{e} is released from rest. The distance travelled by the electron in a time t is$ (1) $\frac{2 m _{e} t ^{2}}{e}$ (2) $\frac{eE t ^{2}}{2 m _{e}}$ (3) $\frac{m _{e} g t ^{2}}{eE}$ (4) $\frac{2 E t ^{2}}{e m _{e}}$ 46. $A galvanometer of resistance 20Ω gives a deflection of 5 divisions when 1 mA current flows through it. The galvanometer scale has 50 divisions. To convert the galvanometer into a voltmeter of range 25 volt, we should connect a resistance of$ (1) $1240Ω in series$ (2) $2480Ω in series$ (3) $2180Ω in parallel$ (4) $20Ω in parallel.$ 47. $A galvanometer having a coil resistance of 100 Ω gives a full scale deflection, when a current of 1 mA is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of 10 A, is:$ (1) $2$ (2) $0.1$ (3) $3$ (4) $0.01$ 48. $A galvanometer having a resistance of 20Ω and 30 divisionon both sides has figure of merit 0.005 ampere/division. Theresistance that should be connected in series such that itcan be used as a voltmeter upto 15 volt, is:$ (1) $100Ω$ (2) $120Ω$ (3) $80Ω$ (4) $125Ω$ 49. $Specific resistance of a conductor increases with$ (1) $increase in temperature$ (2) $increase in cross‐section area$ (3) $increase in cross‐section and decrease in length$ (4) $decrease in cross‐section area.$ 50. $The difference of temperature in a material can convert heat energy into electrical energy.To harvest the heat energy, the material should have$ (1) $high thermal conductivity and high electrical conductivity$ (2) $low thermal conductivity and low electrical conductivity$ (3) $high thermal conductivity and low electrical conductivity$ (4) $low thermal conductivity and high electrical conductivity$ 51. $The velocity of charge carriers of current (about 1 ampere) in a metal under normal conditions is of the order of$ (1) $a fraction of mm/sec$ (2) $velocity of light$ (3) $several thousand meters/second$ (4) $a few hundred meters per second$ 52. $The deflection in galvanometer falls to (\frac{1}{4})^{th} when it is shunted by 3Ω . If additional shunt of 2Ω is connected to earlier shunt, the deflection in galvanometer falls to$ (1) $\frac{1}{2}$ (2) $(\frac{1}{3})^{rd}$ (3) $(\frac{1}{4})^{th}$ (4) $(\frac{1}{8.5})^{th}$ 53. $The effective resistance of a parallel connection that consists of four wires of equal length, equal area of cross-section and same material is 0.25Ω . What will be the effective resistance, if they are connected in series? [NEET 2021]$ (1) $0.25Ω$ (2) $0.5Ω$ (3) $1Ω$ (4) $4Ω$ 54. $Three copper wires of lengths and cross‐ sectional areas are (l, A), (2 l, A /2) and (l /2, 2 A) . Resistance is minimum in$ (1) $wire of cross‐sectional area 2 A$ (2) $wire of cross‐sectional area \frac{A}{2}$ (3) $wire of cross‐sectional area A$ (4) $same in all three cases.$ 55. $In a meter bridge experiment, when a nichrome wire is in the right gap, the balancing length is 60 cm . When the nichrome wire is uniformly stretched to increase its length by 20 % and again connected in the right gap, the new balancing length is nearly$ (1) $61 cm$ (2) $31 cm$ (3) $51 cm$ (4) $41 cm$ 56. $The resistivity of a metal is 1 \times 10^{- 8} Ωm . If it contains 9 \times 10^{28} electrons per m^{3} then the relaxation time of electrons inside the metal is nearly (electron mass = 9 \times 10^{- 31} kg)$ (1) $4 \times 10^{- 14} s$ (2) $7 \times 10^{- 14} s$ (3) $1.0 \times 10^{- 14} s$ (4) $9 \times 10^{- 14} s$ 57. $If voltage across a bulb rated 220 V, 100 W drops by 2.5 % of its rated value, the percentage of the rated value by which the power would decrease is$ (1) $5 %$ (2) $20 %$ (3) $10 %$ (4) $2.5 %$ 58. $Two conductors have the same resistance at 0ºC but their temperature coefficients of resistance are α_{1} and α_{2} . The respective temperature coefficients of their series and parallel combinations are nearly$ (1) $\frac{α _{1} + α _{2}}{2}, α_{1} + α_{2}$ (2) $α_{1} + α_{2}, \frac{α _{1} + α _{2}}{2}$ (3) $α_{1} + α_{2}, \frac{α _{1} α _{2}}{α _{1} + α _{2}}$ (4) $\frac{α _{1} + α _{2}}{2}, \frac{α _{1} + α _{2}}{2}$ 59. $A wire of resistance 160 Ω is melted and drawn in a wire of one-fourth of its length. The new resistance of the wire will be$ (1) $16 Ω$ (2) $10 Ω$ (3) $640 Ω$ (4) $40 Ω$ 60. $The drift velocity of electrons in a conducting wire connected to a cell is V_{d} . If the length of the wire is doubled and area of cross-section is halved then the drift velocity of electrons becomes.$ (1) $V_{d}$ (2) $V_{d} 2$ (3) $2 V_{d}$ (4) $4 V_{d}$