MCQs of Current Electricity

Current Electricity MCQs

MCQs of Current Electricity

Showing 51 to 60 out of 119 Questions

51.

Two wires which are made of the same material have the same cross-sectional area, but different lengths l₁ and l₂ are used as fuse wires. If same value of the current flowing through them, in the same time, which wire fuse early ?

(a)	wire having length l₁
(b)	wire having length l₂
(c)	both will melt at the same time
(d)	none of these

52.

A and B are two electric bulbs with their ratings respectively 40 W, 110 V and 100 W and 110 V. Find their respective filament resistances. If the bulbs are connected in series with a supply of 220 V, which bulb will fuse ?

(a)	R_A = 22 Ω, R_B = 100 Ω, bulb A
(b)	R_A = 160 Ω, R_B = 50 Ω, both bulb A and B
(c)	R_A = 302.5 Ω, R_B = 121 Ω, bulb A
(d)	R_A = 300 Ω, R_B = 150 Ω, bulb B

53.

The internal resistance of a cell of emf 4 V is 0·1 Ω. It is connected to a resistance of 3·9 Ω The voltage across the cell will be _____.

(a)	0·1 V
(b)	3·8 V
(c)	3·9 V
(d)	2 V

54.

The ratio of cross- sectional areas of two conducting wires made up of same material and having same length is 1 : 2. What will be the ratio of heat produced per second in the wires, when same current is flowing in them ?

(a)	$1 : \sqrt{2}$
(b)	$1 : 1$
(c)	$1 : 4$
(d)	$2 : 1$

55.

Two similar cells, whether joined in series or in parallel, have the same current through an external resistance of 2 Ω. The internal resistance of each cell is _____.

(a)	1·5 Ω
(b)	0·5 Ω
(c)	2 Ω
(d)	1 Ω

56.

Two electric bulbs have ratings respectively of 25 W, 220 V and 100 W, 220 V. If the bulbs connected in series with a supply of 440 V, which bulb will fuse ?

(a)	100 W bulb
(b)	25 W bulb
(c)	Both (A) and (B)
(d)	None of the above

57.

The maximum power dissipated in an external resistance R, when connected to a cell of emf E and internal resistance r, will be _____.

(a)	$\frac{E^{2}}{4}$
(b)	$\frac{E^{2}}{2 r}$
(c)	$\frac{E^{2}}{3 r}$
(d)	$\frac{E^{2}}{4 r}$

58.

The carbon resistor has three orange bands. The maximum value of resistance offered by the resistor will be _____.

(a)	49·6 kΩ
(b)	33 kΩ
(c)	39·6 kΩ
(d)	26·4 kΩ

59.

Two wires of same material having lengths and in the radii in the ratio of 3 : 4 and 3 : 2 respectively, are connected in parallel with a potential source of 6 V. The ratio of currents flowing through them, I₁ : I₂ = _____.

(a)	1 : 3
(b)	1 : 2
(c)	3 : 1
(d)	2 : 1

60.

Two wires of equal length and equal diameter and having resistivities

ρ_{1}

and

ρ_{2}

are connected in series. The equivalent resistivity of the combination is _____.

(a)	$(ρ_{1} + ρ_{2})$
(b)	$\frac{ρ_{1} ρ_{2}}{ρ_{1} + ρ_{2}}$
(c)	$\frac{ρ_{1} + ρ_{2}}{2}$
(d)	$\sqrt{ρ_{1} ρ_{2}}$

Showing 51 to 60 out of 119 Questions