How long does it take a 750 W heater operating at full rating to raise the temperature of 1 kg of water from 40oC to 70oC? (Take the specific heat capacity of water as 4200 J kg-1 K-1 and neglect heat losses).
- 84s
- 112s
-
168s
- 280s
- 616s
The correct answer is: C
Explanation
div class="eq-c">pt = mcθΔ; t =mcθΔp
= 1 x 4200 x (70 - 40)750
= 168s