Question

A potentiometer wire has a length 2 m and resistance of 10$\Omega$. It is connected in series with a Resistance of 990 $\Omega$ and a cell of e.m.f. 2V. The potential gradient along the wire is

• A. 0.01 V/m
• B. 0.02 V/m
• C. 0.03 V/m
• D. 0.025 V/m

Answer 1

The correct option is A 0.01 V/m

when $L=2m,R=10\Omega ,R_E=990\Omega ,E=2V$

Potential gradient of wire ($k$)

$k=\frac{V}{L}$ since $I=\frac{E}{R+R_e}$

$V=IR=\frac{ER}{R+R_e}=\frac{2\times 10}{10+990}=\frac{20}{1000}$

$\therefore$ $V=2\times {10}^{-2}$ volt

$k=\frac{2\times {10}^{-2}}{2}$

$k={10}^{-2}V/m$

$k=0.01V/m$