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A room has AC run for 5 hours a day at a voltage of 220V. The wiring of the room consists of Cu of 1 mm radius and a length of 10 m. Power consumption per day is 10 commercial units. What fraction of it goes in the joule heating in wires? What would happen if the wiring is made of aluminium of the same dimensions?
A room has AC run for 5 hours a day at a voltage of 220V. The wiring of the room consists of Cu of 1 mm radius and a length of 10 m. Power consumption per day is 10 commercial units. What fraction of it goes in the joule heating in wires? What would happen if the wiring is made of aluminium of the same dimensions?
CBSE | Class 12 | Current Electricity | NCERT | NCERT Exemplar | Physics
A room has AC run for 5 hours a day at a voltage of 220V. The wiring of the room consists of Cu of 1 mm radius and a length of 10 m. Power consumption per day is 10 commercial units. What fraction of it goes in the joule heating in wires? What would happen if the wiring is made of aluminium of the same dimensions?

Power consumption in a day = 10 units

Power consumption per hour = 2 units

Power consumption = 2 units = 2 kW = 2000 J/s

Power consumption in resistors, P = VI

Which gives I = 9A

We know that resistance, R = ρ l/A

Substituting the values we get, resistance = 4 J/s

This is used in the calculation of power loss in Al wire = 6.4 J/s

Fractional loss in the second wire due to Joule heating is = 0.32%

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