A potentiometer wire has length 4 m and resistance 8\ . The resistance that must be connected in series with the wire and the driving battery of e.m.f. 2 V, so as to get a potential gradient of 1 mV per cm on the wire is

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Correct answer: D. 32\

Potential gradient k = 1 mV/cm = 10^ -3 V 10^ -2 m = 0.1 V/m Length of the potentiometer wire L = 4 m Potential difference across the potentiometer wire V = k × L = 0.1 × 4 = 0.4 V Current in the circuit I = (V)/(R_p) = (0.4)/(8) = 0.05 A Total resistance of the circuit R_ eq = (E)/(I) = (2)/(0.05) = 40\ Resistance to be connected in series R = R_ eq - R_p = 40 - 8 = 32\ Answer: 32\

A potentiometer wire has length 4 m and resistance 8\ . The...

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