Internal battery resistance: When a 100-Ω resistor is connected across the terminals of a battery of emf ε and internal resistance r, the battery delivers 0.794 W of power to the 100-Ω resistor. When the 100-Ω resistor is replaced by a 200-Ω resistor, the battery delivers 0.401 W of power to the 200-Ω resistor. What are the emf and internal resistance of the battery?
A) ε = 10.0 V, r = 5.02 Ω
B) ε = 4.50 V, r = 4.00 Ω
C) ε = 9.00 V, r = 2.04 Ω
D) ε = 9.00 V, r = 1.01 Ω
E) ε = 12.0 V, r = 6.00 Ω

Question

Quizplus · Accepted Answer

By using the power formula P = V^2/R and the relation V = ε - Ir, we can set up equations for both scenarios and solve for ε and r. The correct values that satisfy both conditions are ε = 9.00 V and r = 1.01 Ω.

Internal Battery Resistance: When a 100-Ω Resistor Is Connected Across