Question

An electric iron of power 1.5 kW is used for 30 minutes to press clothes. Calculate the electrical energy consumed in (a)kilowatt hour (b)joule

Answer 1

Answer:

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

Explanation:

1. Find the wattage on the appliance label. Most high-power appliances have an energy label on the back or base of the appliance. ...

2. Multiply wattage by hours used each day. ...

3. Divide the result by 1,000. ...

4. Multiply your answer by the number of days you're measuring. ...

5. Multiply by the cost of electricity per kWh.