(a) An electric iron consumes energy at a rate of 880 W when heating is at the maximum rate and 330 W when…
(a) An electric iron consumes energy at a rate of 880 W when heating is at the maximum rate and 330 W when the heating is at the minimum. If the source voltage is 220 V, calculate the current and resistance in each case.
(b) What is heating effect of electric current ?
(c) Find an expression for the amount of heat produced when a current passes through a resistor for some time.
Solution
(a) When heating is at maximum rate.
Power, P = 880 W
Voltage, V = 220 V
Current, I = P/V = 880/220 = 4A
Resistance, R = V/I = 220/4 = 55 Ω
When heating is at minimum rate
Power, P = 330W
Voltage, V = 220 V
Current, I = P/V = 330/220 = 3/2 = 1.5A
Resistance, R = V/I = 220/1.5 = 146.6 Ω
(b) When electric current is passed through a resistor, electrical energy is dissipated and appears as heat energy.
(c) H = I²Rt / H=VIt