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

Question

A potentiometer wire has length 4 m and resistance 8 Ω . The resistance that must be connected in series with the wire and an accumulator of e.m.f. 2V , so as to get a potential gradient 1 mV per cm on the wire is :, 32 Ω, 40 Ω, 44 Ω, 48 Ω

MARKS App · Accepted Answer

d V d t = 1 m V c m For a potentiometer 1 c m of wire has 1 m V of voltage So, 400 c m has 0.4 V . Given R must be connected in series Δ V = 0.4 = 2 8 + R × 8 8 + R = 16 0.4 = 160 4 = 40 ⇒ R = 32 Ω

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