Question

If a 50 W bulb is lighted for 3 h daily. Give the energy consumed in 30 days.

Answer 1

now 50 watt means bulb consume 50 joule of energy every second
so in 3 hours we have 3*60*60 seconds
so daily(1day) energy consume=3*60*60*50 joules
in 30 days it's equal to 30*3*60*60*50 joules

Answer 2

Energy = Power × Time
= 50 Watt × 30 days × 3 hour/day
= 4500 Watt hour
= 4.5 kWh

∴ Energy consumed in 30 days is 4.5 kWh