Class 12 NEET Physics Current Electricity Questions Part 1

The current through the potentiometer wire is
I=‌

E0

(r+r1)

and the potential difference across the wire is
V=Ir=‌

E0r

(r+r1)

The potential gradient along the potentiometer wire is
k=‌

V

L

=‌

E0r

(r+r1)L

As the unknown e.m.f. E is balanced against length I of the potentiometer wire,
∴E=kl=‌

E0r

(r+r1)

‌

l

L