An electrical appliance having a resistance of 200Ω is operated at 200 V. Calculate the energy consumed by the appliance in 5 minutes (i) in joule, (ii) in kWh.
(i) R=200 ΩV=200 Vt=5 mins=300 s
Now, energy consumed, H=V2Rt=2002200×300=60000 J
(ii) P=V2R=2002200=200 W=0.2kW
t=5 mins=560 h=112 h
Energy consumed, H=Pt=0.2×112=0.0167 kWh