Current Electricity PYQs Set 4 (PDF)

Set 4 of 21 · Questions 91-120 of 612

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Mere Teacher · Previous Year Questions NEET Physics · Current Electricity · Set 4 (Q91-120)
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91. $In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitude are found to be 6V and 2V respectively. The modulation index is$ (1) $100%$ (2) $80%$ (3) $60%$ (4) $50%$ 92. $Sensitivity of potentiometer can be increased by$ (1) $increasing the emf of the cell$ (2) $increasing the length of the potentiometer wire$ (3) $decreasing the length of the potentiometer wire$ (4) $None of the above$ 93. $The current sensitivity of moving coil galvanometer is increased by 25%. This increase is achieved only changing in the number of turns of coils and area of cross section of the wire while keeping the resistance of galvanometer coil constant. The percentage change in the voltage sensitivity will be:$ (1) $+25%$ (2) $-50%$ (3) $-25%$ (4) $Zero$ 94. $The energy that will be ideally radiated by a 100 kW transmitter in 1 hour is [NEET 2022]$ (1) $36 \times 10^{4} J$ (2) $36 \times 10^{5} J$ (3) $1 \times 10^{5} J$ (4) $36 \times 10^{7} J$ 95. $The number of electrons flowing per second in the filament of a 110 W bulb operating at 220 V is : ( Given (e = 1.6 \times 10^{- 19} C)$ (1) $6.25 \times 10^{17}$ (2) $1.25 \times 10^{19}$ (3) $6.25 \times 10^{18}$ (4) $31.25 \times 10^{17}$ 96. $Two resistors of 100Ω each are connected in series with a 9 V battery. A voltmeter of 400Ω resistance is connected to measure the voltage drop across one of the resistors. The voltmeter reading is____V.$ (1) $2$ (2) $3$ (3) $4$ (4) $4.5$ 97. $A cell can supply currents of 1 A and 0.5 A via resistances of 2.5Ω and 10Ω respectively. The internal resistance of the cell is$ (1) $2Ω$ (2) $3Ω$ (3) $4Ω$ (4) $5Ω$ 98. $A current of 10 A exists in a wire of cross-sectional area of 5 mm^{2} with a drift velocity of 2 \times 10^{- 3} ms^{- 1} . Thenumber of free electrons in each cubic meter of the wire is$ (1) $2 \times 10^{6}$ (2) $625 \times 10^{25}$ (3) $2 \times 10^{25}$ (4) $1 \times 10^{23}$ 99. $In the experiment of Ohm's law, a potential difference of 5.0 V is applied across the end of a conductor oflength 10.0 cm and diameter of 5.00 mm . The measured current in the conductor is 2.00 A. The maximum permissible percentage error in the resistivity of the conductor is:-$ (1) $3.9$ (2) $8.4$ (3) $7.5$ (4) $3$ 100. $A galvanometer of resistance G is shumted with a resistance of 10 % of G . The part of the total current that flows through the galvanometer is$ (1) $\frac{I}{11}$ (2) $\frac{I}{12}$ (3) $\frac{I}{10}$ (4) $\frac{I}{55}$ 101. $Two electric bulbs, rated at (25 W, 220 V) and (100 W, 220 V), are connected in series across a 220 V voltage source. If the 25W and 100 W bulbs draw powers P_{1} and P_{2} respectively, then:$ (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) $P_{1} = 9 W, P_{2} = 16W$ 102. $A flow of 1 0^{7} electrons per second in a conducting wire constitutes a current of$ (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) $1.6 \times 1 0^{12} A .$ 103. $Consider the following two statements. (I) Kirchhoff’s junction law follows from the conservation of charge. (II) Kirchhoff’s loop law follows from the conservation of energy. Which of the following is correct?$ (1) $Both (I) and (II) are wrong$ (2) $(I) is correct and (II) is wrong$ (3) $(I) is wrong and (II) is correct$ (4) $Both (I) and (II) are correct$ 104. $Five identical cells each of internal resistance 1Ω and emf 5V are connected in series and in parallel with an external resistance 'R'. For what value of 'R', current in series and parallel combination will remain the same?$ (1) $1Ω$ (2) $25Ω$ (3) $5Ω$ (4) $10Ω$ 105. $The resistance of a wire is 5 ohm at 50º C and 6 ohm at 100ºC. The resistance of the wire at 0ºC will be$ (1) $2 ohm$ (2) $1 ohm$ (3) $4 ohm$ (4) $3 ohm$ 106. $The battery of a mobile phone is rated as 4.2 V, 5800 mAh . How much energy is stored ir it when fully charged?$ (1) $87.7 kJ$ (2) $43.8 kJ$ (3) $48.7 kJ$ (4) $24.4 kJ$ 107. $If a wire is stretched to make it 0.1% longer, its resistance will:$ (1) $increase by 0.05%$ (2) $increase by 0.2%$ (3) $decrease by 0.2%$ (4) $decrease by 0.05%$ 108. $A cylindrical metallic wire is stretched to increase its length. If the resistance of the wire is increased by 4 %, then the percentage increase in its length is$ (1) $4 %$ (2) $8 %$ (3) $1 %$ (4) $2 %$ 109. $A potentiometer is an accurate and versatile device to make electrical measurements of E.M.F. because the method involves:$ (1) $cells$ (2) $potential gradients$ (3) $a condition of no current flow through the galvanometer$ (4) $a combination of cells, galvanometer and resistance$ 110. $An electric power line having total resistance of 2Ω, delivers 1 kW of power at 250 V. The percentage efficiency of transmission line is____.$ (1) $100$ (2) $92.5$ (3) $96.9$ (4) $86.5$ 111. $Across a metallic conductor of non-uniform cross section a constant potential difference is applied. The quantity which remains constant along the conductor is$ (1) $current$ (2) $drift velocity$ (3) $electric field$ (4) $current density$ 112. $In potentiometer experiment, the balancinglength is 8 m when two cells E_{1} and E_{2} are joined in series. When two cells are connected in opposition the balancing length is 4 m . The ratio of the e.m.f. of the two cells (\frac{E _{1}}{E _{2}}) is$ (1) $1 : 2$ (2) $2 : 1$ (3) $1 : 3$ (4) $3 : 1$ 113. $Identify the correct statement among the following:$ (1) $Resistivity of metals decreases with temperature because more electrons are available for conduction.$ (2) $Resistivity of metals increases with temperature because number of electrons decreases.$ (3) $Resistivity of metals increases with temperature because number of collisions between electrons increases$ (4) $Resistivity of metals decreases with temperature because superconductivity sets in.$ 114. $Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R . Assertion A : An electron microscope can achieve better resolving power than an optical microscope. Reason R : The de Broglie's wavelength of the electrons emitted from an electron gun is much less than wavelength of visible light. choose the correct answer from the options given below:$ (1) $A is true but R is false.$ (2) $Both A and R are true but R is NOT the correct explanation of A .$ (3) $Both A and R are true and R is the correct explanation of A .$ (4) $A is false but R is true.$ 115. $A galvanometer has resistance of 100Ω and a current of 10 mA produces full scale deflection in it. The resistance to be connected to it in series, to get a voltmeter of range 50 volt is$ (1) $3900Ω$ (2) $4000Ω$ (3) $4600Ω$ (4) $4900Ω$ 116. $A metal has 9 \times 10^{28} conduction electrons per m^{3} and its resistivity is 1 \times 10^{- 8} Ω . m. If the drift speed of an electron in the metal is 1.6 \times \frac{10 ^{6} m}{s} then its mean free path is (mass of electron = 9 \times 10^{- 31} kg and charge of electron (= 1.6 \times 10^{- 19} C)$ (1) $55.5 nm$ (2) $78.0 nm$ (3) $40.0 nm$ (4) $62.5 nm$ 117. $A potentiometer consists of a wire of length 4 m and resistance 10 Ω . It is connected to a cell of e.m.f. 2 V ne potential difference per unit length of the wire will be$ (1) $5 V / m$ (2) $2 V / m$ (3) $0.5 V / m$ (4) $10 V / m$ 118. $A circuit to verify Ohm's law uses ammeter and voltmeter in series or parallel connected correctly to the resistor. In the circuit$ (1) $Ammeter is always connected in series and voltmeter in parallel$ (2) $Both ammeter and voltmeter must be connected in parallel$ (3) $Ammeter is always used in parallel and voltmeter is series$ (4) $Both ammeter and voltmeter must be connected in series$ 119. $The H amount of thermal energy is developed by a resistor in 10 s when a current of 4A is passed through it. If the current is increased to 16A, the thermal energy developed by the resistor in 10 s will be:$ (1) $H$ (2) $16H$ (3) $\frac{H}{4}$ (4) $4H$ 120. $A potentiometer balances at 44 cm when a cell of internal resistance 1Ω is in the secondary circuit. To obtain the balancing point at 40 cm, the resistance to be connected parallel to cell is$ (1) $20Ω$ (2) $10Ω$ (3) $30Ω$ (4) $5Ω$