✨ What is Light?
Light is a form of energy that we can see. Light travels in straight lines at incredibly fast speeds (about 300,000 km per second!). We need light to see things — without light, everything would be dark.
💡 Sources of Light
☀️
Natural Sources
Sun, stars, lightning, fire, bioluminescence
💡
Artificial Sources
Light bulbs, torches, screens, LEDs
Luminous vs Non-Luminous
- Luminous — produces its own light (sun, candle, torch)
- Non-luminous — doesn't produce light, only reflects it (moon, book, you!)
➡️ How Light Travels
Key Facts
- Light travels in straight lines
- Light can travel through transparent materials (glass, air)
- Some light passes through translucent materials (frosted glass)
- Light cannot pass through opaque materials (wood, metal)
🔄 Light Behaviour
Reflection
When light bounces off a surface. Smooth surfaces (mirrors) give clear reflections.
When light bends as it passes from one material to another (like air to water). This is why a straw looks "bent" in a glass of water!
👤 Shadows
How Shadows Form
When light hits an opaque object, it creates a shadow on the opposite side because light cannot pass through.
- Close to light source = bigger shadow
- Far from light source = smaller shadow
- Time of day changes shadow length (sun position)
✏️ Activities
- Shine a torch at an object
- Move the torch closer — what happens to the shadow?
- Move it further away — what changes?
- Try different angles
Luminous or Non-luminous?
- The moon: ___________
- A candle flame: ___________
- A mirror: ___________
- A TV screen: ___________
Why do shadows get longer in the evening?
👩🏫 Teacher Notes
- Science: Physical World — energy