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.

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1 Answers

(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

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