Question

In the circuit given, consider R₁ = r, R₂ = 2r and power supply of voltage V.

Determine the power consumed by the circuit in each of the following instances: 

i. when the switch is open 

ii. when the switch is closed 

iii. while the switch is closed, the resistor R₂ is heated so that its resistance is doubled.

Answer 1

i. When the switch is open: 

Power₁ = V₂ /R₁ = V₂ /r

ii. When the switch is closed, 

Power₂ = V₂ /R_eq = 3V² /2r

iii. When R₂ is heated, its value = 4r ohm

Power₃ = 5V²/4r