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A battery of emf 10 V and internal resistance 3 $\Omega$ is connected to a resistor and the circuit current is 0.5 A. The terminal voltage of the battery when the circuit is closed is
A8.5 V
B10 V
C11.5 V
D1.5 V
Answer & Solution
Correct answer: A. 8.5 V
1. Terminal voltage on discharge is $V = \varepsilon - Ir$.
2. Internal drop: $Ir = 0.5 \times 3 = 1.5\ \text{V}$.
3. $V = 10 - 1.5 = 8.5\ \text{V}$.
4. 11.5 V wrongly adds the drop; 1.5 V is only the internal drop, not the terminal voltage.
_Source: NCERT Class 12 Physics Ch 3 "Current Electricity", p.14_
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