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Flashcards in The Cost of Electricity Deck (11)
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1
Q

What do electrical appliances do?

A

Transfer electrical energy into other forms.

2
Q

The amount of energy that is transferred by an appliance depends on what?

A

Its power - how fast the appliance can transfer it.

Amount of time the that appliance is switched on.

3
Q

What is energy usually measured in?

A

Joules.

1 J is the amount of energy transferred by a 1 W appliance in 1 second.

4
Q

What is power usually measured in?

A

Watts or Kilowatts.

A 5 kW appliance transfers 5000 J in 1 second.

5
Q

When you are dealing with large amounts of electrical energy, what is it easier to think of?

A

Power and time in kilowatts and hours.

Rather than watts and seconds.

6
Q

What is the standard unit of electrical energy?

A

Kilowatt-hours not joules.

7
Q

Equation for energy transfer.

A

Energy = power x time.

8
Q

Define Kilowatt hour.

A

Is the amount of electrical energy used by a 1 kW appliance left on for 1 hour.

9
Q

Name the 2 easy formulas for calculating the cost of electricity.

A
Units = kW x hours.
Cost = Units x price.
10
Q

The units on a electricity meter are usually in what?

A

kWh.

11
Q

What do you do if in the exam they ask you to work out the total energy that’s been used over a particular period of time?

A

Subtract the meter reading at the start of the time from the reading at the end to work it out.