Question

At what rate per hour does a 1 kW heater convert electrical energy into heat?

(a) 3.5 MJ

(b) 2.5 MJ

(c) 3.6 MJ

(d) 2.6 MJ

I got this question in exam.

This question is from Basic Energy Concepts in division Energy Balance of Bioprocess Engineering

Answer 1

The correct choice is (c) 3.6 MJ

For explanation I would say: Energy = power x time

1 kW is 1,000 watts

Since 1 watt is 1 joule per sec

1,000 watts is 1,000 joules per sec

In one hour there are 3,600 seconds

Substituting in the equation energy = 1,000 x 3,600 joules

= 3,600,000 joules

= 3.6 MJ

Therefore a 1 kW heater converts 3.6 MJ of electrical energy into heat per hour.