Question

An electric iron consumes energy at a rate of 840w when heating is at the max rate and 360w when heating is at minimum.the voltage is 220v,what are the current and resistance in each case.

Answer 1

Maximum values .

P = V I

= > 840 W = 220 v × I

= > I = 840 W / 220 v

= > I = 4 A

V = I R

= > R = V / I

= > R = 220 v / 4 A

= > R = 55 ohms

Minimum values

P = V I

= > I = P / V

= > I = 360 W / 220 v

= > I = 1.64 A

V = I R

= > R = V / I

= > R = 220 v / 1.64 A

= > R = 134.15 ohms

ANSWER :

55 ohms , 4 A

134.15 ohms , 1.64 A