Question

solve this question with correct formula and technique.

Answer 1

V = iR

For a battery with internal resistance “r”
V = i × (R + r)

For 1st case
V = 1.5A × (3Ω + r) ……[1]

For 2nd case
V = 1A × (5Ω + r) ………[2]

Equate both the equations
1.5 (3 + r) = 5 + r
4.5 + 1.5r = 5 + r
0.5r = 0.5
r = 1 Ω

∴ Intenal resistance of battery is 1 Ω