Tiêu đề 2. Current Electricity (S.C.Q.) E 300+.pdf ✅

PHYSICS Q.301 The resistance of 3 and 6 are joined in series and connected across a battery of emf 10 V and internal resistance 1. The power dissipated by battery is - (A) 3 W (B) 8 W (C) 9 W (D) 10 W [D] Q.302 A 24 V battery of internal resistance 4 is connected to a variable resistor. The rate of heat production in the resistor is maximum when the current in the circuit is - (A) 2 A (B) 3 A (C) 4 A (D) 6 A [B] Q.303 If energy consumption of this circuit is 150 watt then find the value of resistance –AIEEE-2002] 2 15V R (A) 2  (B) 4  (C) 6  (D) 8  [C] Q.304 A wire when connected to 220 V mains supply has power dissipation P1. Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is P2. The P2 : P1 is – [AIEEE-2002] (A) 1 (B) 4 (C) 2 (D) 3 [B] Q.305 The length of a given cylindrical wire is increased by 100%. Due to the consequent decrease in diameter the change in the resistance of the wire will be – [AIEEE-2003] (A) 100% (B) 50% (C) 300% (D) 200% [C] Q.306 A 220 volt, 1000 watt bulb is connected across a 110 volt mains supply. The power consumed will be – [AIEEE-2003] (A) 500 watt (B) 250 watt (C) 1000 watt (D) 750 watt [B] Q.307 A 3 volt battery with negligible internal resistance is connected in a circuit as shown in the figure. The current I in the circuit will be – [AIEEE-2003] I 3 3 3 3V (A) 1.5 A (B) 2 A (C) 1/3 A (D) 1 A [A] Q.308 The total current supplied to the circuit by the battery is – [AIEEE-2004] 2 1.5 6 6V 3 (A) 1 A (B) 2 A (C) 4 A (D) 6 A [C] Q.309 The resistance of the series combination of two resistance is S. When they are joined in parallel the total resistance is P. If S = n P then the minimum possible value of n is – [AIEEE-2004] (A) 4 (B) 3 (C) 2 (D) 1 [A] Q.310 An electric current is passed through a circuit containing two wires of the same material, connected in parallel.If the lengths and radii are in the ratio of 3 4 and 3 2 , then the ratio of the current passing through the wires will be (A) 8/9 (B) 1/3 (C) 3 (D) 2 Sol. [B]  = same R 1 I    2 r I   1 2 2 2 2 1 2 1 r r I I   =  = 4 3 3 2 2        = 1/3
Q.311 The thermistors are usually made of – [AIEEE-2004] (A) Metals with low temperature coefficient of resistivity (B) Metals with high temperature coefficent of resistivity (C) metal oxides with high temperature coefficient of resistivity (D) Semiconducting meterials having low temperature coefficient of resistivity [C] Q.312 Time taken by a 836 W heater to heat one litre of water from 10°C to 40°C is – [AIEEE-2004] (A) 50 s (B) 100 s (C) 150 s (D) 200 s [C] Q.313 A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistance in ohms needed to be connected in series with the coil will be – [AIEEE-2005] (A) 103 (B) 105 (C) 99995 (D) 9995 [D] Q.314 In the circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be – [AIEEE-2005] 500 12V B R A 2V G (A) 200  (B) 100  (C) 500  (D) 1000  [B] Q.315 Two sources of equal emf are connected to an external resistance R. The internal resistances of the two sources are R1 and R2(R2 > R1). If the potential difference across the source having internal resistance R2 is zero, then – [AIEEE-2005] (A) R = R2 × (R1 + R2)/(R2 – R1) (B) R = R2 – R1 (C) R = R1R2/(R1 + R2) (D) R = R1R2/(R2 – R1) [B] Q.316 An energy source will supply a constant current into the load if its internal resistance is – [AIEEE-2005] (A) equal to the resistance of the load (B) very large as compared to the load resistance (C) zero (D) non-zero but less than the resistance of the load [B] Q.317 A material 'B' has twice the specific resistance of 'A'. A circular wire made of 'B' has twice the diameter of a wire made of 'A'. then for the two wires to have the same resistance, the ratio B/A of their respective lengths must be – [AIEEE 2006] (A) 4 1 (B) 2 (C) 1 (D) 2 1 [B] Q.318 The Kirchhoff's first law (i = 0) and second law (iR = E), where the symbols have usual meanings, are respectively based on – [AIEEE 2006] (A) conservation of momentum, conservation of charge (B) conservation of charge, conservation of energy (C) conservation of charge, conservation of momentum (D) conservation of energy, conservation of charge [B] Q.319 The current I drawn from the 5 volt source will be– [AIEEE 2006] 5Volt I 5 10 20 10 10 + – (A) 0.67 A (B) 0.17 A
(C) 0.33 A (D) 0.5 A [D] Q.320 In a Wheatstone's bridge, three resistances P, Q and R are connected in the three arms and the fourth arm is formed by two resistances S1 and S2 connected in parallel. The condition for the bridge to be balance will be – [AIEEE 2006] (A) Q P = 1 2 1 2 2S S R(S + S ) (B) Q P = S1 S2 R + (C) Q P = S1 S2 2R + (D) Q P = 1 2 1 2 S S R(S + S ) [D] Q.321 An electric bulb is rated 220 volt – 100 watt. The power consumed by it when operated on 110 volt will be – [AIEEE 2006] (A) 25 watt (B) 50 watt (C) 75 watt (D) 40 watt [A] Q.322 The resistance of wire is 5 ohm at 50oC and 6 ohm at 100oC. The resistance of the wire at 0oC will be – [AIEEE 2007] (A) 2 ohm (B) 1 ohm (C) 4 ohm (D) 3 ohm [C] Q.323 A 5 V battery with internal resistance 2  and a 2V battery with internal resistance 1 are connected to a 10 resistor as shown in the figure. [AIEEE-2008] 5V 2 10 2V 1 P2 P1 The current in the 10  resistor is - (A) 0.03 A P1 to P2 (B) 0.03 A P2 to P1 (C) 0.27 A P1 to P2 (D) 0.27 A P2 to P1 [B] Directions : Questions No. 22 and 23 are based on the following paragraph. Consider a block of conducting material of resistivity ‘’ shown in the figure. Current ‘I’ enters at ‘A’ and leaves from ‘D’. We apply superposition principle to find voltage ‘V’ developed between ‘B’ and ‘C’. The calculation is done in the following steps : (i) Take current ‘I’ entering from ‘A’ and assume it to spread over a hemispherical surface in the block. (ii) Calculate field E(r) at distance ‘r’ from A by using Ohm’s law E = j, where j is the current per unit area at ‘r’. (iii) From the ‘r’ dependence of E(r), obtain the potential V(r) at r. (iv) Repeat (i), (ii) and (iii) for current ‘I’ leaving ‘D’ and superpose results for ‘A’ and ‘D’. A B C D I I a b a V Q.324 For current entering at A, the electric field at a distance ‘r’ from A is - [AIEEE-2008] (A) 2 r I (B) 2 2 r I   (C) 2 4 r I   (D) 2 8 r I   [B] Q.325 V measured between B and C is - [AIEEE-2008] (A) a I – (a b) I +  (B) 2 a I   – 2 (a b) I  +  (C) 2 (a b) I  −  (D) a I   – (a b) I  +  [B] Q.326 A battery of internal resistance 4  is connected to the network of resistance as shown. In order that maximum power can be delivered to the network, the value of R in ohm should be [IIT- JEE 95]
R R R R 4R 6R 4 R (A) 9 4 (B) 2 (C) 3 8 (D) 18 [B] Q.327 In the circuit shown in fig , each battery is 5V and has an internal resistance of 0.2 ohm. The reading in ideal voltmeter V is – [IIT - 97] V (A) 0 V (B) 5 V (C) 40 V (D) 25 V [A] Q.328 The equivalent resistance between points A and B of the circuit given below – [IIT - 97] A 2R 2R R B (A) 5 R (B) R/2 (C) 2 R (D) R [B] Q.329 A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is/are – [IIT - 97] (A) current, electric field and drift speed (B) drift speed only (C) current and drift speed (D) current only [D] Q.330 In the circuit shown in figure , the current through– [IIT - 98] 3 2 2 2 2 2 9V 8 8 4 I A B D C (A) the 3 resistor is 0.50 A (B) the 3 resistor is 0.25 A (C) the 4 resistor is 0.50 A (D) the 4 resistor is 0.25 A [D] Q.331 When a potential difference is applied across, the current passing through [IIT-99] (A) a metal at 0 K is zero (B) a semiconductor at 0 K is zero (C) a metal at 0 K is finite (D) a p-n diode at 300 K is finite, if is reverse biased [B] Q.332 Two wires of equal diameters of resistivities 1 and 2 and lengths x1 and x2 are joined in series. The equivalent resistivity of the combination is- [IIT Sc. 2001] (A) 1 2 1 1 2 2 x x x x +  +  (B) 1 2 1 2 2 1 x x x x −  − (C) 1 2 1 2 2 1 x x x x +  +  (D) 1 2 1x1 2x2  +   +  [A] Q.333 In the given circuit, it is observed that the current I is independent of the value of the resistance R6. Then the resistance values must satisfy – [IIT Sc. 2001] R5 R1 R2 R3 R4 R6 I (A) R1R2R5 = R3R4R6