# P5: Electricity in the house

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A 40 W light bulb is switched on for 30 minutes. Calculate the energy it transfers.
time taken = 1800 s. E = P x t. = 72,000 J
1 of 6
Calculate the normal current through a 500 W, 230 V heater.
Current = 500 / 230 = 2.2 A.
2 of 6
Calculate the energy transferred in a component when the charge passing through it is 30 C and the potential difference is 20 V.
E = V x Q. = 600 J.
3 of 6
A 230 V, 12 A electric motor in a machine has an efficiency of 60%. Calculate the electrical power supplied to it.
power supplied = current x potential difference. = 2,760 W.
4 of 6
A 230 V, 12 A electric motor in a machine has an efficiency of 60%. Calculate the output power of the motor.
efficiency as a ratio = 60% / 100% = 0.6
5 of 6
A 230 V, 12 A electric motor in a machine has an efficiency of 60%. Calculate the energy per second wasted by the motor.
energy wasted per second = 2760 W - 1660 W = 1,100 W.
6 of 6

## Other cards in this set

### Card 2

#### Front

Calculate the normal current through a 500 W, 230 V heater.

#### Back

Current = 500 / 230 = 2.2 A.

### Card 3

#### Front

Calculate the energy transferred in a component when the charge passing through it is 30 C and the potential difference is 20 V.

### Card 4

#### Front

A 230 V, 12 A electric motor in a machine has an efficiency of 60%. Calculate the electrical power supplied to it.

### Card 5

#### Front

A 230 V, 12 A electric motor in a machine has an efficiency of 60%. Calculate the output power of the motor.