MCQs of Current Electricity

Current Electricity MCQs

MCQs of Current Electricity

Showing 11 to 20 out of 119 Questions

11.

Masses of three wires of copper are in the ratio 5 : 3 : 1 and their lengths are in the ratio 1 : 3 : 5. The ratio of their electrical resistances are _____.

(a)	5 : 3 : 1
(b)	$\sqrt{125} : 15 : 1$
(c)	1 : 15 : 125
(d)	1 : 3 : 5

12.

The resistance of a 10 m long potentiometer wire is 20 Ω. It is connected in series with a 3 V battery and 10 Ω resistor. The potential difference between two points separated by distance 30 cm is equal to _____ .

(a)	0.02 V
(b)	0.06 V
(c)	0.1 V
(d)	1.2 V

13.

n identical cells each of emf ε and internal resistance r are connected in parallel with resistor R. The current flowing through resistor R is, _____ .

(a)	$\frac{n ε}{R + n r}$
(b)	$\frac{n ε}{nR + r}$
(c)	$\frac{ε}{R + r}$
(d)	$\frac{ε}{nR + r}$

14.

A wire is uniformly stretched to make its area of cross - section {\frac{1}{n}}^{th} times (n > 0) . What will be its new resistance ?

(a)	$\frac{1}{n^{2}} times$
(b)	$n^{2} times$
(c)	$\frac{1}{n} times$
(d)	n times

15.

If the current in an electric bulb increases by 1 %, what will be the change in the power of a bulb ? [Assume that the resistance of the filament of a bulb remains constant.]

(a)	increases by 1 %
(b)	decreases by 1 %
(c)	increases by 2 %
(d)	decreases by 2 %

16.

Two bulbs of 220 V and 100 W are first connected in series and than in parallel with supply of 220 V. Total power in both the cases will be _____ .

(a)	50 W, 100 W
(b)	100 W, 50 W
(c)	200 W, 150 W
(d)	50 W, 200 W

17.

In a hydrogen atom, the electron is moving in a circular orbit of radius 5.3 x 10^-11 m with a constant speed of 2.2 x 10⁶ ms^-1. The electric current formed due to the motion of electron is _____

(a)	1.12 A
(b)	1.06 mA
(c)	1.06 A
(d)	1.12 mA

18.

A ring of radius R and linear charge density λ on its surface is performing rotational motion about an axis perpendicular to its plane. If the angular velocity of the ring is ω, how much current is constituted by the ring ?

(a)	Rωλ
(b)	R²ωλ
(c)	Rω²λ
(d)	Rωλ²

19.

A cell supplies a current of 0.9 A through a 2 Ω resistor and current of 0.3 A through a 7 Ω resistor. What is the internal resistance of the cell ?

(a)	0.5 Ω
(b)	1.0 Ω
(c)	1.2 Ω
(d)	2.0 Ω

20.

A current density of 2.5 Am^-2 is found to exist in a conductor when an electric field of 5 x 10^-8 Vm^-1 is applied across it. The resistivity of a conductor is _____

(a)	1 x 10^-8 Ωm
(b)	2 x 10^-8 Ωm
(c)	0.5 x 10^-8 Ωm
(d)	12.5 x 10^-8 Ωm

Showing 11 to 20 out of 119 Questions