Question

A 2KW heater of capacity 10 litres is used for heating water. The time required to raise the temperature of water by 10 K is

• A. 210 S
• B. 180 S
• C. 240 S
• D. 150 S

Answer 1

The correct option is A 210 S

Mass of water = 10000 gram

Heat required to raise the temperature to $10K=\Delta H=10000\times 10\times 1calorie[\because S_w=1cal/g]$

$\Delta H=42000joules$

Now,

Power = 2000 W

Energy = $P\times t=2000J/s\times t$

$⟹2000t=420000$

$⟹t=210seconds$