Question

An electric heater is rated 2200 VA, 220V. If the heater is operated for 1 hour, calculate the energy consumed:

(i) in kWh

(ii) in J

• A. 2.2 kWh, 792J
• B. 22 kWh, 792J
• C. 2.2 kWh, 792 x 10²J
• D. 2.2 kWh, 792 x 10²J

Answer 1

The correct option is D

2.2 kWh, 792 x 10²J

VA = volt x ampere = watt

P = 2200VA = 2200w = 2.2kw

i) Energy (in kWh) = P ´ t = 2.2 ´ 1 = 2.2kWh

ii) Energy (in J) = P ´ t = 2200 ´ 3600 = 792 ´ 10⁴ J