Question

calculate the heat energy given out by the filament of an electric bulb in 20 sec when the resistance of it is 4 and p.d. acrosss its ends is 12 volt

Answer 1

H=? V=12 V R=4 ohms t=20

H=voltage square/resistance multiplied to time[to numerator]

H=12*12*20/4

H=2880/4

Therefore,H=720 J