⚡ Part 1: Energy Conservation and Efficiency

1. State the Law of Conservation of Energy in your own words:

2. What is the unit for measuring energy?

Watts (W)

Joules (J)

Newtons (N)

Kilograms (kg)

3. A light bulb receives 100 J of electrical energy. It produces 15 J of light energy and the rest is wasted as heat. Calculate:

a) Amount of energy wasted: _______ J

b) Energy efficiency of the light bulb: _______ %

Show your working:

4. Which of the following are examples of energy transformations? (Select all that apply)

A toaster converting electrical energy to heat energy

A solar panel converting light energy to electrical energy

A car engine converting chemical energy to kinetic energy

A battery storing electrical energy

5. Complete this energy chain for a kettle:

_____________ energy → _____________ energy → _____________ energy (useful)

Some energy is also wasted as _____________ energy to the surroundings.

📊 Part 2: Sankey Diagrams

6. What is a Sankey diagram used for in energy studies?

7. In a Sankey diagram, what does the thickness of the arrows represent?

The speed of energy transfer

The amount of energy being transferred

The type of energy transformation

The efficiency of the system

8. A car engine has an energy input of 1000 J. It produces 300 J of useful kinetic energy, 500 J is lost as heat, and 200 J is lost as sound and vibration. Draw a simple Sankey diagram for this system in the box below:

9. Calculate the efficiency of the car engine from question 8:

Efficiency = _______ %

Show your working:

🌱 Part 3: Real-World Applications

10. Explain why understanding energy efficiency is important for:

a) Environmental conservation:

b) Reducing electricity bills:

11. Suggest two ways to improve the energy efficiency of a home heating system:

1.

2.

12. Research Extension: Find one example of an energy chain in your home or school. Describe the energy transformations and estimate where energy might be wasted: