A motor operating on `120 V` draws a current of `2 A` . If the heat is developed in the motor at the rate of `9 cal s^(-1)`, what is the efficiency?

A motor operating on `120 V` draws a current of `2 A` . If the heat is

1.	A motor operating on `120 V` draws a current of `2 A` . If the heat is developed in the motor at the rate of `9 cal s^(-1)`, what is the efficiency?
Answer» Correct Answer - `80.9%` Here`V= 110 V, l = 2A` power supplied to motor `= 1//1 = 110 xx 2 = 220 W` power loss in the form of heat `= 10 cals^(-1)` `= 10 xx 4.2 Js^(-1) = 42 Js^(-1)` power used by motor `= 220 - 42 = 178 W` Effeciency `eta = ("power used by motor")/("power supplied to motor") xx 100` `= (178)/(220) xx 100 = 80.9%`

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A motor operating on `120 V` draws a current of `2 A` . If the heat is developed in the motor at the rate of `9 cal s^(-1)`, what is the efficiency?

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