MCQs of Current Electricity

Current Electricity MCQs

MCQs of Current Electricity

Showing 111 to 119 out of 119 Questions

111.

n resistors of resistance r are connected to a battery of emf

ε

and internal resistance r. The ratio of terminal voltage to emf of battery = _____.

(a)	$n$
(b)	$\frac{n}{n + 1}$
(c)	$\frac{1}{n + 1}$
(d)	$\frac{n + 1}{n}$

112.

Equivalent resistance of n resistors having same resistance r when connected in parallel is R. Equivalent resistance When connected in series = _____.

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

113.

Resistance of a long wire of uniform cross-section is R. It is cut into n equal pieces. Equivalent resistance of these pieces when connected parallel is R', then R' =_____.

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

114.

A wire of radius r has resistance R. if it is converted into a wire of to radius

\frac{r}{2}

, its resistance will be _____.

(a)	16R
(b)	2R
(c)	4R
(d)	zero

115.

Electric current is passed through a resistance

R_{1}

for time t form an electric cell. Now current is passed through a resistance

R_{2}

for the same time from the same cell. Internal resistance of the cell is _____, if the joule heat developed in both resistors is the same.

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

116.

Two resistors are connected (a) in series (b) in parallel. The equivalent resistance in two cases are 9 ohms and 2 ohms respectively. The resistors are _____.

(a)	2 Ω and 7 Ω
(b)	3 Ω and 6 Ω
(c)	3 Ω and 9 Ω
(d)	5 Ω and 4 Ω

117.

Length of a heating filament is reduced by 20 %, then its power will _____.

(a)	decrease by 20 %
(b)	increase by 20 %
(c)	increase by 25 %
(d)	increase by 40 %

118.

What maximum power can be obtained from a battery of emf

ε

and internal resistance r connected with an external resistance R ?

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

119.

A wire of 20 Ω resistance is passed through ice and 220 V is supplied. What is the rate of melting of the ice ? latent heat of melting of ice = 80 cal/g.

(a)	6·56 g/s
(b)	7·2 g/s
(c)	1·92 g/s
(d)	0·85 g/s

Showing 111 to 119 out of 119 Questions