# Usefulness of electrical appliances

HideShow resource information
• Created by: Megan1404
• Created on: 13-03-16 15:14
What is the formula for calculating the energy transferred by an appliance? What are the units?
Energy = Power x Time, kWh, kW, hrs
1 of 5
What is the formula for calculating the cost of using a device?
Total cost = no. of kWhs x cost per kWh
2 of 5
A 3kW electric motor is switched on for 15 mins. How much energy does it transfer during this time?
E = P x t E = 3 x 0.25 E = 0.75kWh
3 of 5
1 kWh of energy costs 8p. On one day 30kWh of electricity were used - how much would this cost?
30 x 8 = 240p/£2.40
4 of 5
During the week a 2kW iron was used for 2.5 hrs. How much energy was transferred?
2 x 2.5 = 5kWh
5 of 5

## Other cards in this set

### Card 2

#### Front

What is the formula for calculating the cost of using a device?

#### Back

Total cost = no. of kWhs x cost per kWh

### Card 3

#### Front

A 3kW electric motor is switched on for 15 mins. How much energy does it transfer during this time?

### Card 4

#### Front

1 kWh of energy costs 8p. On one day 30kWh of electricity were used - how much would this cost?

### Card 5

#### Front

During the week a 2kW iron was used for 2.5 hrs. How much energy was transferred?