A 9 V battery drives a circuit with resistance of 2 Ω. What is the power delivered by the battery?

Study for the IGCSE Physics Electricity. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

Multiple Choice

A 9 V battery drives a circuit with resistance of 2 Ω. What is the power delivered by the battery?

Explanation:
Power delivered by the battery is found using P = VI, and in a resistor circuit the current is I = V/R. With 9 V across 2 Ω, the current is 9/2 = 4.5 A. The power then is P = VI = 9 × 4.5 = 40.5 W. This can also be checked with P = I^2R = (4.5)^2 × 2 = 40.5 W or P = V^2/R = 81/2 = 40.5 W. So the battery delivers 40.5 watts of power.

Power delivered by the battery is found using P = VI, and in a resistor circuit the current is I = V/R. With 9 V across 2 Ω, the current is 9/2 = 4.5 A. The power then is P = VI = 9 × 4.5 = 40.5 W. This can also be checked with P = I^2R = (4.5)^2 × 2 = 40.5 W or P = V^2/R = 81/2 = 40.5 W. So the battery delivers 40.5 watts of power.

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