Question

A potentiometer wire of length 5 m is connected to a battery. For a certain cell having negligible internal resistance, the null point is obtained at 250 cm. If the length of the potentiometer wire is increased by 1 m, where will be the new position of the null point?

Answer 1

Data : L₁ = 5m, 

L₂ = 6m, 

l₁ = 250 cm

E = \(\left(\cfrac{V}L \right)I\)

where V/L is the potential gradient and l is the balancing length.

∴ E₁ = \(\left(\cfrac{V}{L_1 }\right)I_1\) = \(\left(\cfrac{V}{L_2 }\right)I_2\)

I₂ = \(\left(\cfrac{L_2}{L_1}\right)\) x I₁ = \(\cfrac65\) x 250 = 300 cm