A cell gives a current of 0.15A through a resistance of 8...
A cell gives a current of 0.15A through a resistance of 8Ω and 0.3A. When the resistance is changed to 3Ω the internal resistance of the cell is
0.05Ω
1.00Ω
1.50Ω
2.00Ω
2.50Ω
Correct answer is D
The E.M.F of a circuit is given by
E=I(R+r)
Hence, E = 0.15(8+r) = 0.3(3+r)
1.2 + 0.15r = 0.9 + 0.3r
1.2 - 0.9 = 0.3r - 0.15r
0.3 = 0.15r
r = 0.30.15
r = 2Ω