Question

1 kW,220V electric heater is to be used with 220 V d.c. supply.how much heat in calorie is produced per second

Answer 1

power P = 1 kW = 1000 w

time t = 1 sec

heat produced per second in calorie H = (P x t) /J

                                                                  = (1000 x 1) / 4.2

                                                                  = 240 cal/sec