An electric heater of resistance 8 Ω draws 15 A from the service mains for 2 hours. Calculate the rate at which heat is developed in the heater.

Answer:

Given parameters

The resistance of the electric heater (R) = 8 Ω

Current drawn (I) = 15 A

Time = 2 hrs

T = 120 min x 60

Time (T) = 7200 secs

The rate of heat produced by the device in terms of power is expressed as

The heat developed in heater can be calculated using the formula

H = I2RT

H = 15 x 15 x 8 x 7200

H = 12960000

H = 1296 x 104 J

 

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