Year 7 Science · Unit 3 · Lesson 13

Energy Transformation

Foundation Worksheet

Name

Date

Class

Learning Goals

State that energy is never created or destroyed — only transformed.
Identify the useful output and waste energy for common devices.
Calculate efficiency using the formula: (useful output ÷ total input) × 100%.

Warm Up

True or False? Fix the false ones

Circle T or F for each statement. If the statement is false, rewrite it correctly on the line below.

A solar panel creates new energy from sunlight.

Correct it:

A device with 100% efficiency wastes no energy at all.

Correct it:

An electric motor converts kinetic energy into electrical energy.

Correct it:

Waste energy from most devices is usually released as heat or sound.

Correct it:

When a petrol engine runs, some chemical energy is permanently destroyed.

Correct it:

Your Turn

Match each device to its energy transformation

Draw a line connecting each device on the left to its correct energy transformation on the right. Or write the matching letter next to each device.

Device	Your answer	Energy transformation
Electric toaster		A. Chemical (petrol) → kinetic + heat + sound
Solar panel		B. Electrical → light + heat
Petrol car engine		C. Electrical → thermal (heat) + some light
LED light bulb		D. Chemical (food) → kinetic + heat
Human leg muscles		E. Radiant (light) → electrical + heat
Wind turbine		F. Kinetic (wind) → electrical + heat + sound

Show What You Know

1. A hair dryer uses 1 200 J of electrical energy. It delivers 960 J as useful heat to dry your hair. Calculate its efficiency and state what happens to the remaining energy.

Recall 3 marks

2. Explain why no device can ever be 100% efficient. Use the words heat, sound, and conservation of energy in your answer.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?