Current Electricity - Result Question 107
112. If specific resistance of a potentiometer wire is $10^{-7} \Omega m$, the current flow through it is $0.1 A$ and the cross-sectional area of wire is $10^{-6} m^{2}$ then potential gradient will be
[2001]
(a) $10^{-2}$ volt $/ m$
(b) $10^{-4} volt / m$
(c) $10^{-6} volt / m$
(d) $10^{-8}$ volt $/ m$
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Answer:
Correct Answer: 112. (a)
Solution:
- (a) Potential gradient $=$ Potential fall per unit length.
In this case resistance of unit length.
$R=\frac{\rho l}{A}=\frac{10^{-7} \times 1}{10^{-6}}=10^{-1} \Omega$
Potential fall across $R$ is
$V=I . R=0.1 \times 10^{-1}=0.01 volt / m$.
$=10^{-2}$ volt $/ m$
