Question 314: Current Electricity

Question

In a potentiometer experiment, it is found that no current passes through the galvanometer when the
terminals of the cell are connected across 52 cm of the potentiometer wire. If the cell is shunted by a
resistance of 5 $$\Omega$$, a balance is found when the cell is connected across 40 cm of the wire. Find the internal
resistance of the cell.

Accepted Answer

Internal resistance of potentiometer,
r = $$\left( {{E \over V} - 1} ight) 	imes R$$
Initially when no current passes through the galvanometer then
emf, E = K (52)
here K = potential gradient
After cell is shunted by a resistance 5 $$\Omega $$, then,
Terminal voltage, V = K(40)
$$	herefore\,\,\,$$ r = $$\left( {{{52K} \over {40K}} - 1} ight)$$ $$ 	imes $$ 5
= $$\left( {{{26} \over {20}} - 1} ight)$$ $$ 	imes $$ 5
= 1.5 $$\Omega $$

Answer

2.5 $$\Omega$$

Answer

1 $$\Omega$$

Answer

1.5 $$\Omega$$

Answer

2 $$\Omega$$

Current Electricity

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