Question

4. Consider a 60W light bulb plugged into a 120V socket, and a 100W light bulb plugged into another 120V socket Recall that a bulb's brightness is related to the amount of power (in watts) that is dissipated as heat and light. a Through which light bulb is more current passing? b. Which light bulb filament has more resistance? c. If these light bulbs were connected together in series into the same 120V outlet, which light bulb will be brighter? Use the model to explain.

Answer 1

P_1 = 60 W V = 120 V P_2 = 100 W V = 120 V P_1 = V^2/R_1 R_1 = 120 times 120/60 = 240 Ohm R_2 = 120 times 120/100 = 144 Ohm P_1 = V I_1 I_1 = P_1/V = 60/120 = 1/2 = 0.5 A I_2 = P_2/V = 100/120 = 5/6 = 0.83 A So through second bulb the current pass more \r\n R_1 = 240 Ohm R_2 = 144 Ohm So first bulb has greater resistance P_2 = I^2 R The brightness is proportional to 120 v The power dissipation when the bulbs are connected in series with each other the current is same Brightness R So the first bulb will glow brighter.