Question

A refrigerator works between 4°C and 30°C. It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is (Take 1 cal = 4.2 joules). 

Options

• 236.5 W

• 2365 W

• 2.365 W

• 23.65 W

Answer 1

236.5 W

Explanation:

`"Q"_2/"W" = "T"_2/("T"_1 - "T"_2)`

here, T₂ = 4°C = 277 K

T₁ = 303 K

Q₂ = 600 cal

∴ `600/"W" = 277/(303 - 277)`

∴ W = `600/10.5 ≈ 56  "cal"`

∴ P = `"W"/"t" = 56/(1"s") xx 4.2`

∴ P = 236.5 W