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Question
An electric heater is rated 1500 W. How much energy does it use in 10 hours?
Solution
Here, the power of the electric heater, P = 1500 W
Time for which it is used, t = 10 h
Energy used by the electric heater, i.e.,
W = P × t
= 1500 W × 10 h
= 15000 W h
= 15 kW h
Energy consumed = `15 "kW h" × (3.6 xx 10^6 "J")/(1 "kW h")`
= 5.4 × 107J ...(∵ 1 kW h = 3.6 × 106 J)
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