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Magnetic Effects of Electric Current
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02/08/2021 12:15 pm
Topic starter
(a) 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.
(b) Which of the following fuse ratings would be suitable for this electric iron?
1 A, 3 A, 5 A, 13 A
1 Answer
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02/08/2021 12:17 pm
(a) V = 230V, P = 750 W, t = 30/60 = 0.5hr
(i) Let max current be I
We have P = VI
750 = 230 x I
I = 3.26 A
(ii) Electric energy consumed, E = P x t
= 0.75kW x 0.5h = 0.375 kWh
No. of units used in 30 min = 0.375
(b) 5 A fuse rating will be suitable for this electric iron as the maximum current for this iron is 3.26 A.