Question 449: Current Electricity

Question

A cell, shunted by a 8 $$\Omega$$ resistance, is balanced across a potentiometer wire of length 3 m. The balancing length is 2 m when the cell is shunted by 4 $$\Omega$$ resistance. The value of internal resistance of the cell will be ____________ $$\Omega$$.

Accepted Answer

$${{{\varepsilon _1}8} \over {{r_1} + 8}} =3c$$
$${{{\varepsilon _1}4} \over {{r_1} + 4}} =2c$$
$$ \Rightarrow {{2({r_1} + 4)} \over {{r_1} + 8}} = {3 \over 2}$$
$$ \Rightarrow {r_1} = 8\,\Omega $$

Current Electricity

A cell, shunted by a 8 $\Omega resistance, is balanced across a potentiometer wire of length 3 m. The balancing length is 2 m when the cell is shunted by 4 \Omega resistance. The value of internal resistance of the cell will be ____________ \Omega$.

Choose the correct answer: