A potentiometer wire of length 4 m has a potential gradient $K = 0.5$ V/m. The EMF of a cell that balances at length 80 cm from one end is:
A2.00 V
B0.20 V
C0.40 V
D1.00 V
Answer & Solution
Correct answer: C. 0.40 V
$\varepsilon = K\ell = 0.5 \times 0.80 = 0.40$ V.
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