Calculate the time in which 4.8 kJ of energy would be expended when an electric heater of resistance 1.8 x 103Ω is used on a 240 V mains supply. (Neglect heat losses to the surrounding).
A
150.0s
B
90.0s
C
36.0s
D
20.0s
E
2.7s.
Verified Correct Answer: A.
Physical Principles & Numerical Solution
E = V2t/R
t = ER/V2 = 4800 x 1.8 x 103/240 x 240 = 150s
Source: Myschool Past Questions Archive (Record #24287)