A water heater of power 2000   W is used to heat water. The specific heat capacity of water is 4200…

A water heater of power 2000 W is used to heat water. The specific heat capacity of water is 4200 J kg-1 K-1. The efficiency of heater is 70%. Time required to heat 2 kg of water from 10°C to 60°C is _____ s.

(Assume that the specific heat capacity of water remains constant over the temperature range of the water).

Solution

Heat provided to water will be responsible for increase in temperature. Therefore, we can write

η×P×t=M×s×ΔT

Now, η=70100=0.7 and energy=power×time.

Therefore,

t=2×4200×60°-10°0.7×2000 s=300 s

Asked in: JEE Main 2023 (31 Jan Shift 2)

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