Question

Derive the SI unit of power. An electric bulb is rated 15 watts. What does it mean?What is the energy consumed in joules if it is used for 10 minutes .

Answer 1

The SI unit of power is Watt. It cannot be derived.
An electric bulb is rated 15 watts means it consumes 15 joules of energy per second.
Energy consumed is the product of power and time.
E=P x t
here P=15 W=0.015 kW
t=10 min=10/60=1/6 h
So, E=0.015 x 1/6=0.0025 kWh