Question

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

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Answer 1

At maximum the current is 4A and resistance is 55Ω

At minimum the current is 1.636A and resistance is 134.45Ω

Step-by-step explanation:

The computation of the current and the resistance in each case is shown below:

At the time when it is heated at max rate,

power, P = 840W

V = 220V

As We know that

P = VI

840 = 220 × I

I = 840 ÷ 220

I = 4 A

Now

R = V ÷ I

= 220 ÷4

= 55 Ω

Hence, the current is 4A and resistance is 55Ω

At the time When it is heated at minimum rate,

power, P = 360W

V = 220V

As We know that

P = VI

360 = 220 × I

I = 360 ÷ 220

I = 1.636 A

Now

R = V÷ I

= 220 ÷1.636

= 134.45 Ω

Hence, the current is 1.636A and resistance is 134.45Ω