Question

The resistivity of potentiometer wire is 40 × 10^-8 ohm - metre and its area of cross-section is 8 × 10^-6 m². If 0.2 ampere current is flowing through the wire, the potential gradient of the wire is ______.

Options

• 10^-1 V/m

• 10^-2 V/m

• 10^-3 V/m

• 10^-4 V/m

Answer 1

The resistivity of potentiometer wire is 40 × 10^-8 ohm - metre and its area of cross-section is 8 × 10^-6 m². If 0.2 ampere current is flowing through the wire, the potential gradient of the wire is 10^-2 V/m.

Explanation:

`"R" = (rho"I")/"A"`

∴ `"R"/"I" = rho/"A" = (40 xx 10^-8)/(8 xx 10^-6) = 5 xx 10^-2 ` V/m

Potential gradient is given by,

`"V"/"I" = "IR"/"I" = 0.2 xx 5 xx 10^-2 = 10^-2` V/m