A household refrigerator with a coefficient of performance 1.2 removes heat from refrigerated space

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11.Thermodynamics

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A household refrigerator with a coefficient of performance $1.2$ removes heat from the refrigerated space at the rate of $60\ kJ/min$ .What would be cost of running this fridge for one month ( $30$ days) ....... $Rs.$ (assuming each day it is used for $4$ hours and cost of one electrical unit is $6\ Rs$ .)

A

$180$

B

$300$

C

$480$

D

$600$

Solution

$W=\frac{\phi C}{\operatorname{cop}}=\frac{60 \times 10^{3}}{60 \times 1.2} \mathrm{J} / \mathrm{s}=\frac{10^{3}}{1.2} \mathrm{J} / \mathrm{s}$

No of units consumed

$=\frac{\left(\frac{10^{3}}{1.2}\right)(4)(30)}{1000}=100 \mathrm{units}$

cost of energy $=(6)(100)=600 \mathrm{Rs}$

$\therefore(4)$

Standard 11

Physics

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