An electric heater is rated 1500W. How much energy does it use in 10 hours ?

Explanation

Here, Power, P = 1500 W
`= (1500)/(1000) kW`
= 1.5 kW
And, Time, t = 10 h
Now, `"Power " = ("Energy used")/("Time taken")`
So, `1.5 kW = ("Energy used")/(10 h)`
And Energy used `= 1.5 kW xx 10 h`
= 15 kWh `" "` (or 15 units)
Thus, the energy consumed is 15 kWh or 15 units.