1 (a) P = VI P
power in W
V p.d. in V
I current in A
3000
= 240 x I
I=3000/240
=12.5A
(b) V = IR
240=12.5R
R
= 240/12.5 = 19.2 Ω
(c) 3 kW = 3000 W = 3000 joules per second
Energy used in 1 min = 3000 x 60 = 180 000 J
2 8A 31.25Ω
3 Resistance depends upon temperature
4 1 641 600 J
5 4800J
6 6
7 2.083 kW
8 1920W 1687.5 W
9 .64m
10 50kW 0.072W
