Question

In the circuit diagram, calculate the power consumed in the circuit when:

1. the switch S₁ is closed, and the switch S₂ is open.
2. the switch S₂ is closed, and the switch S₁ is open.

Answer 1

Power consumed is given by P = `V^2/R`, where V = 5 V

(a) When S₁ is closed and S₂ is open, only the 60 Ω resistor is in the circuit.

P = `5^2/60 = 25/60 = 5/12 W ≈ 0.42 W`

(b) When S₂ is closed and S₁ is open, only the 20 Ω resistor is in the circuit.

P = `5^2/20 = 25/20 = 5/4 W = 1.25 W`