Current Electricity PYQs Set 7 (PDF)

Set 7 of 21 · Questions 181-210 of 612

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Mere Teacher · Previous Year Questions NEET Physics · Current Electricity · Set 7 (Q181-210)
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181. $A (100 W, 200 V) bulb is connected to a 160 volts supply. The power consumption would be$ (1) $100 W$ (2) $125 W$ (3) $64 W$ (4) $80 W$ 182. $A student is provided with a variable voltage source V, a test resistor R_{T} = 10Ω, two identical galvanometers G_{1} and G_{2} and two additional resistors, R_{1} = 10 MΩ and R_{2} = 0.01Ω . For conducting an experiment to verify ohm's law, the most suitable circuit is:$ (1) (2) (3) (4) 183. $In an atom electron revolve around the nucleus along a path of radius 0.72Å making 9.4 \times 10^{18} revolutions per second. The equivalent current is [given e = 1.6 \times 10^{- 19} C]$ (1) $1.4 A$ (2) $1.2 A$ (3) $1.8 A$ (4) $1.5 A$ 184. $A potentiometer wire of length 10 m is connected in series with a battery. The emf of a cell balances against 250 cm length of wire. If length of potentiometer wire is increased by 1 m, the new balancing length of wire will be$ (1) $2.00 m$ (2) $2.25 m$ (3) $2.50 m$ (4) $2.75 m$ 185. $The mean free path of electrons in a metal is 4 \times 1 0^{- 8} m . The electric field which can give on an average 2 eV energy to an electron in the metal will be in units V / m$ (1) $5 \times 1 0^{- 11}$ (2) $8 \times 1 0^{- 11}$ (3) $5 \times 1 0^{7}$ (4) $8 \times 1 0^{7}$ 186. $The resistance of a wire is ‘R’ ohm. If it is melted and stretched to ‘n’ times its original length, its new resistance will be$ (1) $\frac{R}{n}$ (2) $n^{2} R$ (3) $\frac{R}{n ^{2}}$ (4) $nR$ 187. $An electric toaster has resistance of 60Ω at room temperature (27^{\circ} C) . The toaster is connected to a 220 V supply. If the current flowing through it reaches 2.75 A, the temperature attained by toaster is around : (if (α = 2 \times \frac{10 ^{- 4}}{^{\circ} C})$ (1) $694^{\circ} C$ (2) $1235^{\circ} C$ (3) $1694^{\circ} C$ (4) $1667^{\circ} C$ 188. $A galvanometer of resistance G is converted into a voltmeter of range 0 - 1 V by connecting a resistance R_{1} in series with it. The additional resistance that should be connected in series with R_{1} to increase the range of the voltmeter to 0 - 2 V will be$ (1) $G$ (2) $R_{1}$ (3) $R_{1} + G$ (4) $R_{1} - G$ 189. $In a conductor, if the number of conduction electrons per unit volume is 8.5 \times 10^{28} m^{- 3} and mean free time is 25 fs (femto second), it's approximate resistivity is: (m_{e} = 9.1 \times) 10^{- 31} kg)$ (1) $10^{- 6} Ωm$ (2) $10^{- 7} Ωm$ (3) $10^{- 8} Ωm$ (4) $10^{- 5} Ωm$ 190. $A 4 μF capacitor is charged to 400 V If its plates are joined through a resistance of 2 kΩ, then heat produced in the resistance is$ (1) $0.64 J$ (2) $1.28 J$ (3) $0.16 J$ (4) $0.32 J$ 191. $For full scale deflection of total 50 divisions, 50mV voltage is required in galvanometer. The resistance of galvanometer if its current sensitivity is 2 div/mA will be:$ (1) $1Ω$ (2) $5Ω$ (3) $4Ω$ (4) $2Ω$ 192. $A galvanometer having a resistance of 20Ω and 30 divisions on both sides has figure of merit 0.005 ampere/division. The resistance that should be connected in series such that it can be used as a voltmeter upto 15 volt, is:$ (1) $80Ω$ (2) $100Ω$ (3) $120Ω$ (4) $125Ω$ 193. $Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is 8 volt and the average resistance per km is 0.5Ω The power loss in the wire is:$ (1) $19.2 W$ (2) $19.2 kW$ (3) $19.2 J$ (4) $12.2 kW$ 194. $A conducting wire of cross-sectional area 1 cm^{2} has 3 \times 10^{23} charge carriers per m^{3} . If wire carries a current of 24 mA, then drift velocity of carriers is$ (1) $5 \times 10^{- 2} m / s$ (2) $0.5 m / s$ (3) $5 \times 10^{- 3} m / s$ (4) $5 \times 10^{- 6} m / s$ 195. $A filament bulb (500 W, 100 V) is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R is [NEET 2016]$ (1) $230Ω$ (2) $46Ω$ (3) $26Ω$ (4) $13Ω$ 196. $In a Wheat stone's bridge, three resistances P, Q and R are connected in the three arms and the fourth arm is formed by two resistances S_{1} and S_{2} connected in parallel. The condition for the bridge to be balanced will be$ (1) $\frac{P}{Q} = \frac{R ( S _{1} + S _{2} )}{2 S _{1} S _{2}}$ (2) $\frac{P}{Q} = \frac{R}{S _{1} + S _{2}}$ (3) $\frac{P}{Q} = \frac{2 R}{S _{1} + S _{2}}$ (4) $\frac{P}{Q} = \frac{R ( S _{1} + S _{2} )}{S _{1} S _{2}}$ 197. $The quantity of a charge that will be transferred by a current flow of 20 A over 1 hour 30 minute period is$ (1) $10.8 \times 10^{3} C$ (2) $10.8 \times 10^{4} C$ (3) $5.4 \times 10^{3} C$ (4) $1.8 \times 10^{4} C$ 198. $When the terminals of a cell are connected by a wire of resistance 4Ω, the potential difference across the cell is 1.6 V . If a wire of the same resistance is connected in parallel with the first, the potential difference becomes 1.33 V . The emf and internal resistance of the cell are respectively$ (1) $1 V, 1Ω$ (2) $2 V, 1Ω$ (3) $1 V, 2Ω$ (4) $2 V, 2Ω$ 199. $A galvanometer having a coil resistance of 60 Ω shows full scale deflection when a current of 1.0 A passes through it. It can be converted into an ammeter to read currents upto 5.0 A by$ (1) $putting in parallel a resistance of 240$ (2) $putting in series a resistance of 15$ (3) $putting in series a resistance of 240$ (4) $putting in parallel a resistance of 15$ 200. $A wire of resistance R and length L is cut into 5 equal parts. If these parts are joined parallely, then resultant resistance will be:$ (1) $\frac{1}{25} R$ (2) $\frac{1}{5} R$ (3) $25 R$ (4) $5R$ 201. $To compare EMF of two cells using potentiometer the balancing lengths obtained are 200 cm and 150 cm. The least count of scale is 1 cm. The percentage error in the ratio of EMFs is____.$ (1) $1.65$ (2) $1.45$ (3) $1.75$ (4) $1.16$ 202. $An electrical power line, having a total resistance of 2Ω delivers 1 kW at 220 V . The efficiency of the transmission line is approximately$ (1) $85 %$ (2) $96 %$ (3) $72 %$ (4) $91 %$ 203. $The colour code for a carbon resistor of resistance 0.28 kΩ \pm 10 % is$ (1) $Red, Grey, Silver, Silver$ (2) $Red, Green, Silver$ (3) $Red, Grey, Brown, Silver$ (4) $Red, Green, Brown, Silver$ 204. $A potentiometer has a uniform wire of length 5 m . A battery of emf 10 V and negligible internal resistance is connected between its ends. A secondary cell connected to the circuit gives balancing length at 200 cm . The emf of the secondary cell is$ (1) $2 V$ (2) $8 V$ (3) $4 V$ (4) $6 V$ 205. $A wire of resistance 2R is stretched such that its length is doubled. Then the increases in its resistance is$ (1) $6R$ (2) $4R$ (3) $3R$ (4) $2R$ 206. $A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively$ (1) $both remain the same$ (2) $1.1 times, 1.1 times$ (3) $1.2 times, 1.1 times$ (4) $1.21 times, same$ 207. $A current of 2 A is passing through a metal wire of cross sectional area 2 \times 10^{- 6} m^{2} . If the number density of free electrons in the wire is 5 \times 10^{26} m^{- 3}, the drift speed of electrons is (given e = 1.6 \times 10^{- 19} C)$ (1) $\frac{1}{16} ms^{- 1}$ (2) $\frac{1}{40} m s^{- 1}$ (3) $\frac{1}{80} m s^{- 1}$ (4) $\frac{1}{32} m s^{- 1}$ 208. $A wire of resistance 3Ω is stretched to twice its original length. The resistance of the new wire will be$ (1) $1.5Ω$ (2) $3Ω$ (3) $6Ω$ (4) $12Ω$ 209. $In meter bridge experiment, with a standard resistance in the right gap and a resistance coil dipped in water (in a beaker) in the left gap, the balancing length obtained is l. If the temperature of water is increased, the new balancing length is$ (1) $> l$ (2) $< l$ (3) $= 0$ (4) $= l$ 210. $Two 220 volt, 100 watt bulbs are connected first in series and then in parallel. Each time the combination is connected to a 220 volt a . c . supply line. The power drawn by the combination in each case respectively will be$ (1) $50 watt, 100 watt$ (2) $100 watt, 50 watt$ (3) $200 watt, 150 watt$ (4) $50 watt, 200 watt$