Q3 of 12 Page 37

An electric heater of power 920 W is working on a 230 V supply. If current flows for 5 minutes through it, calculate the heat generated.

Given:

Power = 920 W = 920 J/s


(∵ 1 Watt = 1Joule/sec)


Time = 5 mins = 5 × 60 seconds = 300 seconds.


Formula used:


Heat, H = Power × time


⇒ H = 920 J-sec-1 × 300 sec


= 276000 J


= 276 × 103 J


∴ 276 kilo joules energy will be generated in the heater when the current flows for 5 mins.


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