Energy – JSS1 Intermediate Science Lesson Note (Third Term)

WHAT IS ENERGY?

Think about how you feel after running a long race or playing under the sun for hours. You feel “tired,” right? You say, “I don’t have the strength to move.”

In Science, we call that “strength” Energy.

The Definition

Energy is simply the ability to do work.

If you want to lift a heavy bag, kick a ball, or even breathe while you sleep, your body needs energy. Without energy, nothing in the universe can move or change.

The Unit of Energy

Just as we measure height in meters, we measure energy in Joules (J).

FORMS OF ENERGY

Energy is like a chameleon—it can change its appearance. It exists in many different forms. Here are the most common ones:

1. Mechanical Energy: This is the energy of movement. It is divided into two:
   1. Potential Energy: Stored energy (like a stone held high in the air).
   2. Kinetic Energy: Moving energy (like that same stone falling).
2. Chemical Energy: Energy stored in things like food, batteries, and petrol. When you eat, your body “burns” this energy to help you move.
3. Thermal (Heat) Energy: Energy that makes things hot. We use it to cook our food or iron our clothes.
4. Light Energy: Energy that helps us see. The sun and light bulbs are great examples.
5. Sound Energy: Energy produced when things vibrate. When you talk or play a drum, you are creating sound energy.
6. Electrical Energy: The energy that flows through wires to power our TVs and fans.

WHERE DOES ENERGY COME FROM? (SOURCES)

A “source” is where we get something from. We can group energy sources into two main families:

1. Renewable Sources (The “Never-Ending” Sources)

These are sources that do not run out. Nature keeps replacing them.

• The Sun (Solar): The biggest source of energy for the Earth. We can use solar panels to turn sunlight into electricity.
• Wind: We use wind to turn large blades (windmills) to create power.
• Water (Hydro): Falling water from dams (like the Kainji Dam in Nigeria) is used to make electricity.

2. Non-Renewable Sources (The “Finished” Sources)

These are sources that will eventually finish if we use them too much.

• Fossil Fuels: These include Crude Oil (Petrol), Coal, and Natural Gas. Once we burn them, they are gone forever.
• Food: Even though we can grow more food, it is the source of energy for our bodies.

ENERGY TRANSFORMATION AND SUMMARY

One of the coolest things about energy is that it can change from one form to another. This is called Transformation.

• Example 1: When you turn on a torch, the Chemical Energy in the battery turns into Light Energy.
• Example 2: When you rub your palms together quickly, the Mechanical Energy (movement) turns into Heat Energy.

Summary Table

Class Activity

Let’s identify the energy changes! What energy change happens when:

1. A radio is switched on? (Electrical → ______)
2. You eat a bowl of garri and then go to farm? (Chemical → ______)
3. An electric iron is plugged in? (Electrical → ______)

Revision Questions

1. Define Energy in your own words.
2. Mention three renewable sources of energy.
3. Why is the Sun called the “primary source” of energy?
4. What is the unit for measuring energy?

Homework

Look around your house. List five objects and write down the form of energy they use or produce. (Example: Television — Electrical and Sound energy).