How long does it take a 750W heater to raise the temperature of 1kg of water from 20oC to 50oC [specific heat capacity of water = 4200Jkg-1K-1]
A
84s
B
112s
C
168s
D
280s
Verified Correct Answer: C.
Physical Principles & Numerical Solution
Heat energy = Elect. energy
mc\(\theta\) = power x time
1 x 4200 x (50 - 20) = 750 x t
t = 168s
Source: Myschool Past Questions Archive (Record #28180)