An electric heater rated 220V, 1000 W is immersed into a bucket full of water. Calculate the mass of water if the temperature changes from 30°c to 100°c and the current flows for 300seconds. [specific heat capacity of water = 4200 jkg-1 K-1]
A
4.28 kg
B
42.86 kg
C
1.02 kg
D
7.14 kg
Verified Correct Answer: C.
Physical Principles & Numerical Solution
The energy supplied by the heater = heater gained by the water
pt = Mc\(\Delta\)\theta
1000 x 300 = m x 4200(100 - 30)
m = \(\frac{(1000 \times 300)}{4200 \times 70}\) = 1.02 kg
Source: WAEC / JAMB / NECO Classroom Archive (Record #14180)