Question

An electric bulb is rated at 60w, 240v. Calculate it's resistance if the voltage drops to 192v, calculate the energy consumed consumed and the current drawn by the bulb.

Answer 1

P=60W
V=240V
P=V^2/R
R=V^2/P
R=240×240/60
R=960 ohm
If V=192V
P=V^2/R
P=192×192/960
P=38.4 W
Now, P=VI
I=P/V
I=38.4/192
I=0.2A