Embibe Experts Solutions for Chapter: Current Electricity, Exercise 2: Exercise 2

$50 \mathrm{V}$ battery is supplying a current of $10 \mathrm{A}$ when connected to a resistor. If the efficiency of battery at this current is $25\%$ .Then internal resistance of battery is:

In the circuit shown, the value of $R$ in ohm that will result in no current through the $30 \mathrm{V}$ battery, is:

A current of $2 \mathrm{A}$ flows through a $2 \mathrm{\Omega }$ resistor when connected across a battery. The same battery supplies a current of $0.5 \mathrm{A}$ when connected across a $9 \mathrm{\Omega }$ resistor. The internal resistance of the battery is

The electric resistance of a certain wire of iron is $R.$ If its length and radius are both doubled, then

A cell when balanced with potentiometer gave a balanced length of $50 \mathrm{cm}$. $4.5 \mathrm{\Omega }$ external resistance is introduced in parallel with the cell in the secondary circuit, now it is balanced on $45 \mathrm{cm}$. The internal resistance of the cell is:

A primary cell has an e.m.f of $1.5$ volt. When short-circuited it gives a current of $3$ ampere. The internal resistance of the cell is

A potentiometer consists of a wire of length $4 \mathrm{m}$ and resistance $10 \mathrm{\Omega }$. It is connected to a cell of emf $3 \mathrm{V}$. The potential gradient of wire is

Two wires of same metal have the same length but their cross-sections are in the ratio $3:1$. They are joined in series. The resistance of the thicker wire is $10 \mathrm{\Omega }$. The total resistance of the combination is