P2.2.7 - Energy and Power

Question 1

What is the equation used to calculate energy? (the triangle will help…)

Answer 1

Energy (J) = Power (W) x Time (S)

Question 2

What is the equation used to calculate power? (the triangle will help…)

Answer 2

Power (W) = Energy (J) ÷ Time (S)

Question 3

What are the units of energy?

Answer 3

Joules (J)

Question 4

How do you convert minutes into seconds?

Answer 4

Multiply by 60

Question 5

What are the units of power?

Answer 5

Watts (W)

Question 6

How mant Watts are in 1 kW?

Answer 6

1000 W = 1 kW

Question 7

How do you convert hours into seconds?

Answer 7

Multiply by 3600

Question 8

What units do energy companies use to calculate energy costs?

Answer 8

Kilowatt hours (kWh)

Question 9

What is the equation used to calculate the time that an electrical appliance will run for? (the triangle will help…)

Answer 9

Time (s) = Energy (J) ÷ Power (W)

Question 10

What is meant by power?

Answer 10

The amount of energy (joules) transferred by an electrical appliance per second.

Question 11

A microwave that has a higher power rating…

Answer 11

will transfer more energy (joules) per second to the food it is heating.

Question 12

How do you calculate the kilowatt hours of electricity used by a household?

Answer 12

Number of Kilowatts of energy used x number of hours used for.

e.g. 12 kW used for 3 hours

= 12 x 3 = 36kWh