07 Energy 2

Energy is…

• An action that results in using less energy

• The ability to do work or make a change

• Thunder

• the energy of motion

What is power measured in?

• Joules (J)

• Watts (W)

• Kiliwatt-hours (kWh)

• Volts (V)

What type of diagram is used to show energy efficiency?

• Bar chart

• Sankey diagram

• Flow chart

• Power diagram

How do we calculate percentage efficiency?

• (useful energy out ÷ total energy in) × 100

• (useful energy in ÷ total energy out) x 100

• (total energy out ÷ useful energy in) x 100

Calculate the efficiency of a bulb with an input energy of 50J, which outputs 40J of thermal energy and 10J of light energy.

• 10%

• 20%

• 25%

• 50%

You have used 784 kWh of electricity since your last meter reading. Each kWh costs 14p. Calculate the cost of your bill.

• £56.00

• £109.76

• £560.00

• £10976.00

Which kinds of appliances transfer the most energy?

• heaters and cookers

• lights

• TVs and radios

• computers

The Law of Conservation of Energy states:

• Energy can created or destroyed but not transformed

• Energy cannot be created or destroyed, it can only transformed

• Energy can't be created, destroyed or transformed

• Energy cannot be created or destroyed.

• 100%

• 80%

• 40%

• 10%

• 100%

• 10%

• 40%

• 20%