Current Electricity PYQs Set 4 (PDF)

Set 4 of 25 · Questions 91-120 of 723

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Mere Teacher · Previous Year Questions JEE Main Physics · Current Electricity · Set 4 (Q91-120)
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91. $If specific resistance of a potentiometer wire is 1 0^{- 7} Ωm and current flow through it is 0.1 amp., cross‐sectional area of wire is 1 0^{- 6} m^{2} then potential gradient will be$ (1) $1 0^{- 2} volt / m$ (2) $1 0^{- 4} volt / m$ (3) $1 0^{- 6} volt / m$ (4) $1 0^{- 8} volt / m .$ 92. $A wire of length l and resistance 100Ω is divided into 10 equal parts. The first 5 parts are connected in series while the next 5 parts are connected in parallel. The two combinations are again connected in series. The resistance of this final combination is [NEET 2024]$ (1) $26Ω$ (2) $52Ω$ (3) $55Ω$ (4) $60Ω$ 93. $The resistance of platinum wire at 0^{\circ} C is 2Ω and 6.8Ω at 80^{\circ} C . The temperature coefficient of resistance of the wire is [NEET 2023]$ (1) $3\times 1 0^{- 3} \circC-1$ (2) $3\times 1 0^{- 2} \circC-1$ (3) $3\times 1 0^{- 1} \circC-1$ (4) $3\times 1 0^{- 4} \circC-1$ 94. $The resistance of a galvanometer is 50 ohm and the maximum current which can be passed through it is 0.002 A . What resistance must be connected to it order to convert it into an ammeter of range 0 - 0.5 A ?$ (1) $0.05 ohm$ (2) $0.002 ohm$ (3) $0.02 ohm$ (4) $0.2 ohm$ 95. $Heater of electric kettle is made of a wire of length L and diameter d. It takes 4 minutes to raise the temperature of 0.5 kg water by 40K. This heater is replaced by a new heater having two wires of the same material, each of length L and diameter 2d. The way these wires are connected is given in the options. How much time in minutes will it take to raise the temperature of the same amount of water by 40K?$ (1) $4 if wires are in parallel$ (2) $2 if wires are in series$ (3) $1 if wires are in series$ (4) $0.5 if wires are in parallel.$ 96. $Which of the following will NOT be observed when a multimeter (operating in resistance measuring mode) probes connected across a component, are just reversed?$ (1) $Multimeter shows NO deflection in both cases i.e. before and after reversing the probes if the chosen component is capacitor.$ (2) $Multimeter shows NO deflection in both cases i.e. before and after reversing the probes if the chosen component is metal wire.$ (3) $Multimeter shows a deflection, accompanied by a splash of light out of connected component in one direction and NO deflection on reversing the probes if the chosen component is LED.$ (4) $Multimeter shows an equal deflection in both cases i.e. before and after reversing the probes if the chosen component is resistor.$ 97. $In a potentiometer experiment of a cell of cmf 1.25 V gives balancing length of 30 cm . If the cell is replaced by another cell, balancing length is found to be 40 cm . What is the emf of second cell?$ (1) $≃ 1.47 V$ (2) $≃ 1.57 V$ (3) $≃ 1.37 V$ (4) $≃ 1.67 V$ 98. $Four identical cells of emf E and internal resistance r are to be connected in series. Suppose if one of the cell is connected wrongly, the equivalent emf and effective internal resistance of the combination is$ (1) $4E and 2r$ (2) $2E and 2r$ (3) $4E and 4r$ (4) $2E and 4r$ 99. $In the density measurement of a cube, the mass and edge length are measured as (10.00 \pm 0.10) kg and (0.10 \pm 0.01) m respectively. The error in the measurement of density is:$ (1) $0.01 kg / m^{3}$ (2) $0.10 kg / m^{3}$ (3) $0.31 kg / m^{3}$ (4) $0.07 kg / m^{3}$ 100. $In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitude are found to be 6V and 2V respectively. The modulation index is$ (1) $100%$ (2) $80%$ (3) $60%$ (4) $50%$ 101. $Sensitivity of potentiometer can be increased by$ (1) $increasing the emf of the cell$ (2) $increasing the length of the potentiometer wire$ (3) $decreasing the length of the potentiometer wire$ (4) $None of the above$ 102. $The current sensitivity of moving coil galvanometer is increased by 25%. This increase is achieved only changing in the number of turns of coils and area of cross section of the wire while keeping the resistance of galvanometer coil constant. The percentage change in the voltage sensitivity will be:$ (1) $+25%$ (2) $-50%$ (3) $-25%$ (4) $Zero$ 103. $The energy that will be ideally radiated by a 100 kW transmitter in 1 hour is [NEET 2022]$ (1) $36 \times 10^{4} J$ (2) $36 \times 10^{5} J$ (3) $1 \times 10^{5} J$ (4) $36 \times 10^{7} J$ 104. $The number of electrons flowing per second in the filament of a 110 W bulb operating at 220 V is : ( Given (e = 1.6 \times 10^{- 19} C)$ (1) $6.25 \times 10^{17}$ (2) $1.25 \times 10^{19}$ (3) $6.25 \times 10^{18}$ (4) $31.25 \times 10^{17}$ 105. $Two resistors of 100Ω each are connected in series with a 9 V battery. A voltmeter of 400Ω resistance is connected to measure the voltage drop across one of the resistors. The voltmeter reading is____V.$ (1) $2$ (2) $3$ (3) $4$ (4) $4.5$ 106. $A cell can supply currents of 1 A and 0.5 A via resistances of 2.5Ω and 10Ω respectively. The internal resistance of the cell is$ (1) $2Ω$ (2) $3Ω$ (3) $4Ω$ (4) $5Ω$ 107. $A current of 10 A exists in a wire of cross-sectional area of 5 mm^{2} with a drift velocity of 2 \times 10^{- 3} ms^{- 1} . Thenumber of free electrons in each cubic meter of the wire is$ (1) $2 \times 10^{6}$ (2) $625 \times 10^{25}$ (3) $2 \times 10^{25}$ (4) $1 \times 10^{23}$ 108. $In the experiment of Ohm's law, a potential difference of 5.0 V is applied across the end of a conductor oflength 10.0 cm and diameter of 5.00 mm . The measured current in the conductor is 2.00 A. The maximum permissible percentage error in the resistivity of the conductor is:-$ (1) $3.9$ (2) $8.4$ (3) $7.5$ (4) $3$ 109. $A galvanometer of resistance G is shumted with a resistance of 10 % of G . The part of the total current that flows through the galvanometer is$ (1) $\frac{I}{11}$ (2) $\frac{I}{12}$ (3) $\frac{I}{10}$ (4) $\frac{I}{55}$ 110. $Two electric bulbs, rated at (25 W, 220 V) and (100 W, 220 V), are connected in series across a 220 V voltage source. If the 25W and 100 W bulbs draw powers P_{1} and P_{2} respectively, then:$ (1) $P_{1} = 4 W, P_{2} = 16W$ (2) $P_{1} = 16 W, P_{2} = 9W$ (3) $P_{1} = 16 W, P_{2} = 4W$ (4) $P_{1} = 9 W, P_{2} = 16W$ 111. $A flow of 1 0^{7} electrons per second in a conducting wire constitutes a current of$ (1) $1.6 \times 1 0^{- 12} A$ (2) $1.6 \times 1 0^{26} A$ (3) $1.6 \times 1 0^{- 26} A$ (4) $1.6 \times 1 0^{12} A .$ 112. $Consider the following two statements. (I) Kirchhoff’s junction law follows from the conservation of charge. (II) Kirchhoff’s loop law follows from the conservation of energy. Which of the following is correct?$ (1) $Both (I) and (II) are wrong$ (2) $(I) is correct and (II) is wrong$ (3) $(I) is wrong and (II) is correct$ (4) $Both (I) and (II) are correct$ 113. $Five identical cells each of internal resistance 1Ω and emf 5V are connected in series and in parallel with an external resistance 'R'. For what value of 'R', current in series and parallel combination will remain the same?$ (1) $1Ω$ (2) $25Ω$ (3) $5Ω$ (4) $10Ω$ 114. $The resistance of a wire is 5 ohm at 50º C and 6 ohm at 100ºC. The resistance of the wire at 0ºC will be$ (1) $2 ohm$ (2) $1 ohm$ (3) $4 ohm$ (4) $3 ohm$ 115. $The battery of a mobile phone is rated as 4.2 V, 5800 mAh . How much energy is stored ir it when fully charged?$ (1) $87.7 kJ$ (2) $43.8 kJ$ (3) $48.7 kJ$ (4) $24.4 kJ$ 116. $If a wire is stretched to make it 0.1% longer, its resistance will:$ (1) $increase by 0.05%$ (2) $increase by 0.2%$ (3) $decrease by 0.2%$ (4) $decrease by 0.05%$ 117. $A cylindrical metallic wire is stretched to increase its length. If the resistance of the wire is increased by 4 %, then the percentage increase in its length is$ (1) $4 %$ (2) $8 %$ (3) $1 %$ (4) $2 %$ 118. $Resistance of a wire at 0^{\circ} C, 100^{\circ} C and t^{\circ} C is found to be 10Ω, 10.2Ω and 10.95Ω respectively. The temperature t in Kelvin scale is______$ 119. $A potential V0 is applied across a uniform wire of resistance R. The power dissipation is P1. The wire is then cut into two equal halves and a potential of V0 is applied across the length of each half. The total power dissipation across two wires is P2. The ratio of P2 : P1 is x : 1. The value of x is_____.$ 120. $Eight copper wire of length l and diameter d are joined in parallel to form a single composite conductor of resistance R. If a single copper wire of length 2 l have the same resistance (R) then its diameter will be _________ d.$