An electric iron of power 1.5 kW is used for 30 minute to press the clothes. Calculate the electrical energy consumed in (a) kilowatt hour (b) joule.
(a) P = w/t
∴ Eelectrical energy W = P × t
P = 1.5 kW t = 30 minute = 30/60 =1/2 hr
1.5 × 1/2 = 0.75 kwh
(b) 1 kWh = 3.6 × 106 J
∴ 75 kWh =0.75 × 3.6 × 106
= 2.700 × 106
= 2.7 × 106 J
