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
Correct Answer: Option C
Explanation
Heat energy = Elect. energy
mc(theta) = power x time
1 x 4200 x (50 – 20) = 750 x t
t = 168s