A potentiometer wire is 5 m long and a potential difference of 6V is maintained between its ends. Find the emf of a cell which balance against a length of 180 cm of the potentiometer wire.

Explanation

Length of potentiometer wire L = 5 m
Potentiall difference V = 6 volt
Potential gradient `phi = (V)/(L) = (6)/(5) = 1.2 V //m`
Balancing length l = 180 cm
= 1.80 cm
Emf of the cell `E = phi l`
`= 1.2 xx 1.8 = 2.16 V`.