In the potentiometer circuit shown in the figure, the balancing length \( \mathrm{AJ}=60 \mathrm...

In the potentiometer circuit shown in the figure, the balancing length \( \mathrm{AJ}=60 \mathrm{~cm} \) when switch \( \mathrm{S} \) is open. When switch \( \mathrm{S} \) is closed and the value of \( \mathrm{R}=5 \Omega \), the balancing length \( \mathrm{AJ}=50 \mathrm{~cm} \). The internal resistance of the cell \( \mathrm{C}^{\prime} \) is :-
(1) \( 1.2 \Omega \)
(2) \( 1.0 \Omega \)
(3) \( 0.8 \Omega \)
(4) \( 0.6 \Omega \)