A electric iron consumes energy at the rate of
(a) `840 W` when heating is at the maximum rate and
(b) `360 W` when the heating is at the minimum.
The voltage is `220 V`. What are the current and the resistance in each case ?

Explanation

From Eq. (12.19), we know that the power input is P=VI
Thus the current `I=P//V`
(a) When heating is at the maximum rate,
`I=840W//220V=3.82A,`
and the resistance of the electric iron is
`R=V//I=220 v//3.82A=57.60 Omega`.
(b) When heating is at the minimum rate,
`I=360 W//220V=1.64 A,`
and the resistance of the electric iron is
`R=V//I=220V//1.64A=134.15Omega`.