## Class 12 Physics MCQs Current Electricity for JEE/NEET

Here, you will get Class 12 Physics MCQ of Chapter 3 Current Electricity for cracking JEE and NEET/AIIMS. By solving these MCQs of Class 12 Physics Chapter 3 Current Electricity, you will get the confidence to crack JEE or NEET. Practice MCQ Questions for Class 12 Physics with Answers on a daily basis and score well in exams.

## Current Electricity Class 12 MCQs Questions with Answers

Which of the following has a negative temperature coefficient of resistance ?
(a) Tungsten
(b) Carbon
(c) Nichrome
(d) Platinum

When there is an electric current through a conducting wire along its length, then an electric field must exist:
(a) outside the wire but normal to it
(b) inside the wire but parallel to it
(c) inside the wire but normal to it
(d) outside the wire but around it

Answer: (b) inside the wire but parallel to it

For which of the following dependence of drift velocity electric field E is Ohm’s law obeyed.
(a) vd < √E
(b) vd ∝ E
(c) vd ∝ E²
(d) vd = constant

Potentiometer measures the potential difference more accurately than a voltmeter because:
(a) It has a wire of high resistance
(b) It has a wire of low resistance
(c) It does not draw current from external circuit
(d) It draws heavy current from external circuit

Answer: (c) It does not draw current from external circuit

An electric heating element consumes 500 W, when connected to a 100 V line. If the line voltage becomes 150 V, the power consumed will be
(a) 500 W
(b) 750 W
(c) 1000 W
(d) 1125 W

The charge flowing in a conductor varies with time as
q = αt 1/2 βt² + 1/6 γt³
Where α, β, γ are positive constants. Then the initial current (l) is given by the condition

(a) l = α
(b) l = α²
(c) l = α-1
(d) None of these

Two conductors of equal length and radii the ratio of 2 : 3 are; connected in parallel the source of electricity. The ratio of the velocity of electrons in the conductor be
(a) 2 : 3
(b) 4 : 9
(c) 1 : 1
(d) 3 : 2

The phenomenon of super-conductivity was discovered by
(a) Ohm
(b) Onnes
(c) Edison
(d) None of these

The emf of a car battery is about
(a) 2.5 V
(b) 4.5 V
(c) 8.6 V
(d) 12 V

Ohm’s law is valid when the temperature of conductor is
(a) very low
(b) very high
(c) varying
(d) constant

Kirchhoffs first and second laws for electrical circuits are consequences of
(a) conservation of energy
(b) conservation of electrical charge and energy respectively
(c) conservation of electric charge
(d) neither conservation of energy nor electric charge

Answer: (b) conservation of electrical charge and energy respectively

Two wires of copper are of the same length but’have different diameters. When they are connected in series across a battery, the heat generated is H1 When connected in parallel across the same battery, the heat generated during the same time is H2 Then
(a) H1 = H2
(b) H1 < H2
(c) H1 > H2
(d) H1 > H2

In an experiment to measure the internal resistance of a cell by a potentiometer, it is found that the balance point is at a length of 2 m, when the cell is shunted by a 5Ω resistance and is at 3 m when the cell is shunted by a 10Ω resistance. The internal resistance of the cell is
(a) 10 Ω
(b) 15 Ω
(c) 1 Ω
(d) 1.5 Ω

The temperature coefficient of resistance of a wire is 0.00125° C-1. At 27°C, its resistance is 1Ω. The temperature of the wire at which its resistance becomes 2Ω is
(a) 1400 K
(b) 854°C
(c) 1127 K
(d) 1154 K

A current I flows in a wire of circular cross-section with the free electrons travelling with a drift velocity v. The drift velocity of electrons when a current 21 flows in another wire of twice radius and of the same material is
(a) v/2
(b) v
(c) 2v
(d) √2v

A cell of e.m.f. ‘E’ and internal resistance r is connected in series with an external resistance nr. Then the ratio of the terminal potential difference to e.m.f. is
(a) 1n
(b) 1/n+1
(c) n/n+1
(d) n+1/n

The resistivity of alloy manganin is
(a) Nearly independent of temperature
(b) Increases rapidly with increase in temperature
(c) Decreases with increase in temperature
(d) Increases rapidly with decrease in temperature

Answer: (a) Nearly independent of temperature

In a potentiometer of 10 wires, the balance point is obtained on the 7th wire. To shift the balance point to 9th wire, we should
(a) decrease resistance in the main circuit
(b) increase resistance in the main circuit
(c) decrease resistance in series with the cell whose emf is to be measured
(d) increase resistance in series with the cell whose emf is to be determined

Answer: (d) increase resistance in series with the cell whose emf is to be determined

In a Wheatstone bridge if the battery and galvanometer are interchanged then the deflection in galvanometer will
(a) change in previous direction
(b) not change
(c) change in opposite direction
(d) none of these

Combine three resistors 5 Q, 4.5 Q and 3 Q in such a way that the total resistance of this combination is maximum
(a) 12.5 Q
(b) 13.5 Q
(c) 14.5 Q
(d) 16.5 Q

A wire of resistance 3 Ω is cut into three pieces, which are then joined to form a triangle. The equivalent resistance between any corners of the triangle is
(a) 2/3 Ω
(b) 3/2 Ω
(c) 1/2 Ω
(d) 1/3 Ω

The specific resistance of a rod of copper as compared to that of thin wire of copper is
(a) less
(b) more
(c) same
(d) depends upon the length and area of cross-section of the wire

Specific resistance of all metals is mostly affected by
(a) temperature
(b) pressure
(c) magnetic field
(d) volume

How many different resistances are possible with two equal resistors?
(a) 2
(b) 3
(c) 4
(d) 5