The reading on the voltmeter, V, takes the following values: V=6.0V when R=2.0Ω and V=8.0V when R=4.0Ω, Claculate internal resistance for parallel circuit

Answer 1

V = ER/(R + r); V₁ = ER₁/(R₁ + r); 6 = 2E/(2 + r); 8 = 4E/(4 + r); 6/8 = 2(4 + r)/[4(2 + r)]; 16(4 + r) = 24(2 + r);

8 + 2r = 6 + 3r; r = 2Ω