What Is Energy?
Energy is all around us — it powers your phone, lets you hear music, lights up a room, and even helps your body move. But what exactly is energy?
Energy is the ability to do work or cause a change. It cannot be created or destroyed, only transferred from one form to another.
Think about eating breakfast. The chemical energy stored in your food gets transferred into movement energy as you walk to school, and heat energy that keeps your body warm. Energy is always doing something — changing, moving, or being stored.
In this subtopic, we will explore four important forms of energy:
- 🔦 Light energy
- 🔊 Sound energy
- ⚡ Electrical energy
- 🧪 Chemical energy
Scientists often call these forms of energy energy types or energy stores and transfers. In MYP Sciences, we focus on understanding what each form is and where we see it in everyday life.
Light Energy
Light energy is a form of energy that travels as electromagnetic waves and can be detected by our eyes. It is also known as radiant energy.
Light energy travels incredibly fast — about 300,000 kilometres per second in a vacuum (empty space). This is called the speed of light. Light can travel through space, which is why we can see the Sun and distant stars even though there is nothing between us and them.
Sources of light energy include:
- The Sun (natural source — the most important source of light and heat for Earth)
- Light bulbs and LEDs (artificial sources)
- Fire and candles
- Fireflies and some deep-sea creatures (a process called bioluminescence)
What can light energy do?
- Allow us to see the world around us
- Help plants make food through photosynthesis
- Carry information in fibre-optic cables (used in internet connections)
- Produce electricity in solar panels
Imagine dropping a stone into a still pond. Ripples spread out in all directions from the point where the stone landed. Light travels in a similar way — as waves spreading outward from its source in all directions.
Many students think light needs a medium (like air or water) to travel through — but it doesn't! Light can travel through the vacuum of space, which is how sunlight reaches Earth. Sound, however, cannot travel through a vacuum.
9 more sections in this topic
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