CUET · PHYSICS · PYQ PAPER 2025
A cell of emf E is connected across an external resistance R. When a current I is drawn, the potential difference across the electrodes drops to V. The internal resistance r of the cell is :
- A \( [\frac{E-V}{E}] R \)
- B \( [\frac{E-V}{R}] \)
- C \( [\frac{E-V}{I}] R \)
- D \( [\frac{E-V}{V}] R \)
Answer & Solution
Correct Answer
(D) \( [\frac{E-V}{V}] R \)
Step-by-step Solution
Detailed explanation
\( V = E - Ir \) \( Ir = E - V \) \( r = \frac{E - V}{I} \) \( r = \frac{E - V}{V/R} \) \( r = [\frac{E-V}{V}] R \)
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