A potentiometer wire of length 1 m is connected in series with 495 Ω resistance and 2 V battery. If 0.2 mV/cm is the potential gradient, then the resistance of the potentiometer wire is (a) 8 Ω (b) 6 Ω (c) 7 Ω (d) 5 Ω

Answer: (d). k = 0.2 mV/cm = 0.02 V/m, so p.d. across 1 m wire = 0.02 V. (2r)/(495 + r) = 0.02 ⇒ 1.98r = 9.9 r = 5 Ω. So the answer is (d) 5 Ω.

A potentiometer wire of length 1 m is connected in series with 495 Ω… | MHT CET 2024 (4 May, Shift 1)

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Potentiometer

A potentiometer wire of length 1 m is connected in series with $495\ \Omega$ resistance and 2 V battery. If $0.2\text{ mV/cm}$ is the potential gradient, then the resistance of the potentiometer wire is

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Answer: (d)

$k = 0.2\ \text{mV/cm} = 0.02\ \text{V/m}$ , so p.d. across 1 m wire $= 0.02\ \text{V}$ .
$\frac{2r}{495 + r} = 0.02 \Rightarrow 1.98r = 9.9$
$r = 5\ \Omega$ .
So the answer is (d) $5\ \Omega$ .

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