An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at 'minimum heating' it consumes a power of 360 W but at 'maximum heating' it takes a power of 840 W. Calculate the current and resistance in each case.

To find the heat produced by iron in the problem, we need to use an expression for produced power, which depends on the resistance of the iron and the current flowing through the iron.

Pmin = VI


360 = 220XI


I = 1.63amp


R = V/I


R = 220/1.63


R = 134.96ohms


In case of maximum heating we get


We know that


Pmax = VI


840 = 220XI


I = 3.81amp


R = V/I


R = 220/3.81


R = 57.74ohms


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