A potentiometer wire 10 long has a resistance of `40Omega`. It is connected in series with a resistances box and a 2 v storage cell. If the potential gradient along the wire is `0.01(V)/(m)` the resistance unplugged in the box is

Options

A. `260Omega`
B. `760Omega`
C. `960Omega`
D. `1060Omega`

Answer

B

Explanation

Potential gradient along wire `=("potential difference along wire")/("length of wire")`
or `0.1xx10^(-3)=(Ixx40)/(1000)V//cm`
or Current in wire, `I=(1)/(400)A`
or `(2)/(40+R)=(1)/(400)orR=800-40=760Omega`