Discussion Forum

A potentiometer wire, 10 m long, has a resistance of 40Ω. It is connected in series with a resistance box and a 2 V storage cell. If the potential gradient along the wire 0.1 m is V/cm, the resistance unplugged in the box is

Answer:

Explanation:

Potential gradient along wire = $\frac{Potential difference along wire}{length of wire}$

or, 0.1×10^-3 = $\frac{I\times40}{1000}$V/cm

or, Current in wire, I = $\frac{1}{400}$ A

or, $\frac{2}{40+R}$ = $\frac{1}{400}$ or R = 800 - 40=760 Ω