A steam iron draws 6.5 A when connected to a potential difference of 120 V.

Question

(a) What is the power rating of this iron?
1 W
(b) How many joules of energy are produced in 20.0 min?
2 J
(c) How much does it cost to run the iron for 20.0 min at $0.014/kW·h?
$ 3

Answer 1

P =I•U = 6.5•120 =780 W
E = P•t =780•20•60 =9.36•10^5 J.
1 J = 2.78⋅10^ -7 kWh
9.36•10^5 J =0.26 kWt.
0.26 kWt •$0.014/kW•h = $0.00364