an electric cell with nominal voltage E has a resistance of 3Ω connected across it. If the voltage falls to 0.6E, the internal resistance of the cell is

an electric cell with nominal voltage E has a resistance of 3Ω connected across it. If the voltage falls to 0.6E, the internal resistance of the cell is

Answer Details

I = V/R = 0.6E/3 = 0.2E Again, I = E / (R+ϒ) = E / (3+ϒ) Divide eqn (2) by eqn (1) I/I = E / (3+ϒ) x I / 0.2E => 0.2(3+ϒ) = 1 0.6 x 0.2ϒ = 1 ∴0.2ϒ = -0.6 => ϒ = 0.6 / 0.2 = 3Ω ϒ = 3Ω