When connected across a 220 V power supply, an electric bulb consumes 60 W of power. What will be the power consumed if the supply voltage drops to 180 V , and what will it be if the supply is abruptly raised to 240 V ?

Step-by-step solution

The resistance of the electric bulb is given by R = V^2 P Substituting the given values, R = (220)^2 60 , Assuming the resistance of the bulb remains constant, the power consumed at a new voltage V' is P' = (V')^2 R When the supply voltage drops to 180 V : P₁ = (180)^2 (220)^2 60 = ( 180 220 )^2 60 = 81 121 60 40.16 W When the supply voltage is raised to 240 V : P₂ = (240)^2 (220)^2 60 = ( 240 220 )^2 60 = 144 121 60 71.40 W The power consumed will be approximately 40 W and 71 W .