### 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 $\epsilon$ and internal resistance r. The ratio of terminal voltage to emf of battery = _____.
 (a) $\mathrm{n}$ (b) $\frac{\mathrm{n}}{\mathrm{n}+1}$ (c) $\frac{1}{\mathrm{n}+1}$ (d) $\frac{\mathrm{n}+1}{\mathrm{n}}$
112.
Equivalent resistance of n resistors having same resistance r when connected in parallel is R. Equivalent resistance When connected in series = _____.
 (a) $nR$ (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) $nR$ (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) (b) (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 $\epsilon$ and internal resistance r connected with an external resistance R ?
 (a) $\frac{{\epsilon }^{2}}{4r}$ (b) $\frac{{\epsilon }^{2}}{3r}$ (c) $\frac{{\epsilon }^{2}}{2r}$ (d) $\frac{{\epsilon }^{2}}{r}$
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