Question

An electric iron is rated at 230 V, 750 W. Calculate (i) the maximum current, and (ii) the number of units of electricity it would use in 30 minutes.

Answer 1

V=230V, P=750 W, t=30/60=0.5hr 

(i) Let max current be I 

We have P=VI 

750 =230xI 

I= 3.26 A 

(ii) Electric energy consumed, E = Pxt = 0.75kW x 0.5h = 0.375 kWh 

No. of units used in 30 min = 0.375