Poll Results
No votes. Be the first one to vote.
The supply voltage to room is 120 V. The resistance of the lead wires is 6 Ω. A 60 W bulb is already switched on. What is the decrease of voltage across the bulb, when a 240 W heater is switched on in parallel to the bulb?
Given: Supply voltage = 120V, Lead wire resistance = 6Ω, Bulb power = 60W, Heater power = 240W.
using R = V²/P, Bulb resistance = 240, Heater resistance = 60Ω.
Current before: 0.5A, Current after: 2.5A.
Voltage drop increase: 12V.
Closest answer : (c) 13.3V.
Share