When a 19-Ω resistor is connected across a 5-V battery,a current of 489 mA flows.What is the power output delivered by the emf of the battery?
A) 95 W
B) 79.5 W
C) 4.5 W
D) 1.2 W
E) 46.5 W

Question

When a 19-Ω resistor is connected across a 5-V battery,a current of 489 mA flows.What is the power output delivered by the emf of the battery?
A) 95 W
B) 79.5 W
C) 4.5 W
D) 1.2 W
E) ​46.5 W

Quizplus · Accepted Answer

The power output delivered by the emf of the battery can be found using the formula P = IV, where P is power, I is current, and V is voltage. Here, I = 489 mA = 0.489 A, and V = 5 V. Using Ohm's law, we can find the resistance R = V/I = 5/0.489 = 10.211 Ω. However, the question tells us that a 19-Ω resistor is connected across the battery, so the effective resistance in the circuit is R = 19 Ω. Using the formula P = IV again, we get P = (0.489 A)^2 x 19 Ω = 4.472 W ≈ 4.5 W, which is choice C.

When a 19-Ω Resistor Is Connected Across a 5-V Battery,a