Question

A potentiometer wire has resistance of per unit length of 0.1 Ω/m. A cell of e.m.f. 1.5 V balances against a 300 cm length of the wire. Find the current in the potentiometer wire.

Answer 1

Given:

σ = 0.1 Ω/m,

E = 1.5 V,

L = 300 cm = 3 m.

To find:

Current through potentiometer (I) = ?

Formulae:

1. σ = R/L
2. I = E/R

Calculation:

From formula (1),

R = σL

= 0.1 × 3

= 0.3 Ω

From formula (2),

I = 1.5/0.3

= 5 A

Current through the potentiometer wire is 5 A.