TG EAMCET 2 May 2025 Shift 2 Paper

The length of the potentiometer wire is L=10m.
The resistance of the potentiometer wire is
Rω=5Ω
The emf of the cell is E=2.2V
The potential difference across a length of l=660cm of the wire is Vl=1.1V.
l=660cm=6.6m
The potential gradient, K=‌

Vl

l

K=‌

1.1V

6.6m

=‌

1

6

V∕m
The total potential drop across the wire Vω is
‌Vω=K×L
‌Vω=‌

1

6

V∕m×10m=‌

10

6

V=‌

5

3

V
Current, I=‌

Vω

Rω

=‌

‌ 5 3 V

5Ω

=‌

1

3

A
The current in the main circuit is also given by
I‌=‌

E

Rω+r

r‌=‌

E

I

−Rω=‌

2.2V

1 3 A

−5Ω
r‌=(2.2×3)Ω−5Ω
r‌=6.6Ω−5Ω=1.6Ω