A potentionmeter wire has resistance of per unit length of 0.1 Ω/m. A cell of e.m.f. 1.5V balances against 300 cm length of the wire. Find the current in the potentiometer wire.
Given:- σ = 0.1 Ω/m, E = 1.5 V,
L = 300 cm = 3 m.
To find:- Current through potentiometer (I).
Formulae: i. σ = R/L ii. I = E/R
Calculation:- From formula (i),
R = σL
= 0.1 x 3 = 0.3 Ω
From formula (ii),
I = 1.5/0.3 = 5 A
Current through the potentiometer wire is 5 A.