Current Electricity PYQs Set 7 (PDF)

Set 7 of 25 · Questions 181-210 of 723

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher · Previous Year Questions JEE Main Physics · Current Electricity · Set 7 (Q181-210)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
181. $Though the electron drift velocity is small and electron charge is very small, a conductor can carry an appreciably large current because$ (1) $electron number density depends on temperature$ (2) $electron number density is very large$ (3) $relaxation time is small$ (4) $drift velocity of electron is very large.$ 182. $The diameter of a sphere is measured using a vernier caliper whose 9 divisions of main scale are equal to 10 divisions of vernier scale. The shortest division on the main scale is equal to 1 mm . The main scale reading is 2 cm and second division of vernier scale coincides with a division on main scale. If mass of the sphere is 8.635 g, the density of the sphere is:$ (1) $2.0 g / cm^{3}$ (2) $1.7 g / cm^{3}$ (3) $2.2 g / cm^{3}$ (4) $2.5 g / cm^{3}$ 183. $A resistance of 2 Ω is connected across one gap of a meter-bridge (the length of the wire is 100 cm) and an unknown resistance, greater than 2 Ω, is connected across the other gap. When these resistances are interchanged, the balance point shifts by 20 cm. Neglecting any corrections, the unknown resistance is$ (1) $3$ (2) $4$ (3) $5$ (4) $6$ 184. $A metal rod of length 10 cm and a rectangular cross-section of 1 cm \times \frac{1}{2} cm is connected to a battery across opposite faces. The resistance will be$ (1) $maximum when the battery is connected across 10 cm \times 1 cm faces$ (2) $same irrespective of the three faces$ (3) $maximum when the battery is connected across 1 cm \times \frac{1}{2} cm faces$ (4) $maximum when the battery is connected across 10 cm \times \frac{1}{2} cm faces.$ 185. $In a metallic conductor, under the effect of applied electric field, the free electrons of the conductor$ (1) $Drift from higher potential to lower potential$ (2) $Move with the uniform velocity throughout from lower potential to higher potential$ (3) $Move in the straight line paths in the same direction$ (4) $Move in the curved paths from lower potential to higher potential$ 186. $A copper wire of length 10m and radius (10^{- 2} / π) m has electrical resistance of 10Ω . The current density in the wire for an electric field strength of 10 (V / m) is [NEET 2022]$ (1) $10^{4} A / m^{2}$ (2) $10^{6} A / m^{2}$ (3) $10^{- 5} A / m^{2}$ (4) $10^{5} A / m^{2}$ 187. $A current of 5 A passes through a copper conductor (resistivity) = 1.7 \times 10^{- 8}) of radius of cross-section 5 mm . Find the mobility of the charges if their drift velocity is 1.1 \times 10^{- 3} ms .$ (1) $1.8 m^{2} / Vs$ (2) $1.5 m^{2} / Vs$ (3) $1.3 m^{2} / Vs$ (4) $1.0 m^{2} / Vs$ 188. $With the help of potentiometer, we can determine the value of emf of a given cell. The sensitivity of the potentiometer is (A) directly proportional to the length of the potentiometer wire (B) directly proportional to the potential gradient of the wire (C) inversely proportional to the potential gradient of the wire (D) inversely proportional to the length of the potentiometer wire Choose the correct option for the above statements:$ (1) $B and D only$ (2) $A and C only$ (3) $A only$ (4) $C only$ 189. $An electric bulb rated 50 W - 200 V is connected across a 100 V supply. The power dissipation of the bulb is:$ (1) $25 W$ (2) $12.5 W$ (3) $50 W$ (4) $100 W$ 190. $The current in the primary circuit of a potentiometer is 0.2 A. The specific resistance and cross-section of the potentiometer wire are 4 \times 1 0^{-7} ohm meter and 8 \times 1 0^{-7} m^{2} respectively. The potential gradient will be equal to:$ (1) $1 V/ m$ (2) $0.5 V/m$ (3) $0.1 V/m$ (4) $0.2 V/m$ 191. $Which of the following acts as a circuit Which of the following acts as a circuit protection device?$ (1) $fuse$ (2) $conductor$ (3) $inductor$ (4) $switch$ 192. $A wire of resistance R_{1} is drawn out so that its length is increased by twice of its original length. The ratio of new resistance to original resistance is:$ (1) $9 : 1$ (2) $1 : 9$ (3) $4 : 1$ (4) $3 : 1$ 193. $The resistance of a conductor at 150C is 16Ω and at 1000C is 20Ω . What will be the temperature coefficient of resistance of the conductor?$ (1) $0.01 0^{0} C^{- 1}$ (2) $0.03 3^{0} C^{- 1}$ (3) $0.00 3^{0} C^{- 1}$ (4) $0.04 2^{0} C^{- 1}$ 194. $An ammeter of resistance ' R' gives a full scale deflection when a current of 2 A passes through. it. If it is to measure maximum current of 10 A, the required shunt is$ (1) $\frac{R}{4}$ (2) $R$ (3) $2 R$ (4) $\frac{R}{2}$ 195. $A battery with EMF E and internal resistance r is connected across a resistance R . The power consumption in R will be maximum when:$ (1) $R = 2 r$ (2) $R = r /2$ (3) $R = r$ (4) $R = 2 r$ 196. $In good conductors of electricity, the type of bonding that exists is$ (1) $metallic$ (2) $vander Waals$ (3) $ionic$ (4) $covalent.$ 197. $Two equal resistances when connected in series to a battery, consume electric power of 60 W . If these resistance are now connected in parallel combination to the same battery, the electric power consumed will be:$ (1) $60 W$ (2) $240 W$ (3) $120 W$ (4) $30 W$ 198. $By what percentage will the illumination of the lamp decrease if the current drops by 20 % ?$ (1) $46 %$ (2) $26 %$ (3) $36 %$ (4) $56 %$ 199. $To measure the internal resistance of a battery, potentiometer is used. For R = 10Ω, the balance point is observed at l = 500 cm and for R = 1Ω the balance point is observed at l = 400 cm . The internal resistance of the battery is approximately:$ (1) $0.2Ω$ (2) $0.3Ω$ (3) $0.4Ω$ (4) $0.1Ω$ 200. $The time required to raise the temperature of 3 liter of water from 0^{\circ} C to 80^{\circ} C by a heater operated under 200 V having resistance of 50Ω is [specific heat capacity of water is 4200 J kg^{- 1} K^{- 1}] [density of water = 1000 kg / m^{3}]$ (1) $12 min$ (2) $18 min$ (3) $21 min$ (4) $24 min$ 201. $Which of the following graphs correctly represents the variation of heat energy (U) produced in a metallic conductor in a given time as a function of potential difference (V) across the conductor?$ (1) (2) (3) (4) 202. $In a potentiometer experiment the balancing length with a cell is 560 cm . When an external resistance of 10Ω is connected in parallel to the cell, then the balancing length changes by 60 cm . Find the internal resistance of the cell.$ (1) $1Ω$ (2) $2Ω$ (3) $1.2Ω$ (4) $2.1Ω$ 203. $A wire 50 cm long and 1 m m^{2} in cross‐ section carries a current of 4 A when connected to a 2 V battery. The resistivity of the wire is$ (1) $4\times 1 0^{- 6} Ωm$ (2) $1\times 1 0^{- 6} Ωm$ (3) $2\times 1 0^{- 7} Ωm$ (4) $5\times 1 0^{- 7} Ωm$ 204. $In a potentiometer experiment, the balancing point with a cell is at a length 240 cm . On shunting the cell with a resistance of 2Ω, the balancing length becomes 120 cm . The internal resistance of the cell is$ (1) $1Ω$ (2) $4Ω$ (3) $0.5Ω$ (4) $2Ω$ 205. $A (100 W, 200 V) bulb is connected to a 160 volts supply. The power consumption would be$ (1) $100 W$ (2) $125 W$ (3) $64 W$ (4) $80 W$ 206. $A student is provided with a variable voltage source V, a test resistor R_{T} = 10Ω, two identical galvanometers G_{1} and G_{2} and two additional resistors, R_{1} = 10 MΩ and R_{2} = 0.01Ω . For conducting an experiment to verify ohm's law, the most suitable circuit is:$ (1) (2) (3) (4) 207. $In an atom electron revolve around the nucleus along a path of radius 0.72Å making 9.4 \times 10^{18} revolutions per second. The equivalent current is [given e = 1.6 \times 10^{- 19} C]$ (1) $1.4 A$ (2) $1.2 A$ (3) $1.8 A$ (4) $1.5 A$ 208. $A potentiometer wire of length 10 m is connected in series with a battery. The emf of a cell balances against 250 cm length of wire. If length of potentiometer wire is increased by 1 m, the new balancing length of wire will be$ (1) $2.00 m$ (2) $2.25 m$ (3) $2.50 m$ (4) $2.75 m$ 209. $The mean free path of electrons in a metal is 4 \times 1 0^{- 8} m . The electric field which can give on an average 2 eV energy to an electron in the metal will be in units V / m$ (1) $5 \times 1 0^{- 11}$ (2) $8 \times 1 0^{- 11}$ (3) $5 \times 1 0^{7}$ (4) $8 \times 1 0^{7}$ 210. $The resistance of a wire is ‘R’ ohm. If it is melted and stretched to ‘n’ times its original length, its new resistance will be$ (1) $\frac{R}{n}$ (2) $n^{2} R$ (3) $\frac{R}{n ^{2}}$ (4) $nR$