CUET · PHYSICS · PYQ PAPER 2025
A 12 V battery connected to a 6 \( \Omega \), 10 mH coil through a switch drives a constant current in the circuit. The switch is suddenly opened. Assuming that it took 1 ms to open the switch, the average emf induced across the coil would be
- A 10 V
- B 20 V
- C 200 V
- D 12 V
Answer & Solution
Correct Answer
(B) 20 V
Step-by-step Solution
Detailed explanation
\( I = \frac{V}{R} = \frac{12}{6} = 2 \, \text{A} \) \( \Delta I = 0 - I = -2 \, \text{A} \) \( |\text{EMF}_{avg}| = L \left| \frac{\Delta I}{\Delta t} \right| = (10 \times 10^{-3}) \frac{|-2|}{1 \times 10^{-3}} = 20 \, \text{V} \)
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