CBSE Class 12 Physics 2023 Outside Delhi Set 1 Paper

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Question : 4
Total: 35
A cell of emf E is connected across an external resistance R. When current ' T ' is drawn from the cell, the potential difference across the electrodes of the cell drops to V. The internal resistance ' r ' of the cell is

Since, ‌‌I=‌
E
R+r

So, E=Ir+V
∴‌‌r=‌
E−V
I

Or, ‌‌r=(‌
E−V
V
)
R
‌
‌[∵V=IR]
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