- Define and explain Sources of Light in your own words
- Use key terms such as light source accurately
- Apply what you have learned to new examples and questions
- Avoid the common mistakes learners make with this topic
Light lets us see the world, and shadows are light's mysterious partner. Every shadow tells a story about where the light is coming from and what is blocking it. This chapter shines a light on how it all works.
This lesson focuses on Sources of Light: naming natural and artificial light sources, from the Sun to light bulbs.
Naming natural and artificial light sources, from the Sun to light bulbs.
Key ideas
Shadows form when light is blocked
Stand in sunshine and your body blocks the Sun's rays, leaving a dark patch — your shadow — on the ground behind you. Only opaque objects make proper shadows; transparent glass lets the light straight through. The shadow always falls on the opposite side from the light source.
Light travels in straight lines
Light cannot bend around corners — it always moves in straight lines called rays. That is why you cannot see around a wall but you can see down a straight corridor. Shadows have sharp edges because light cannot curve around the object making them.
Key term — light source: Anything that gives out light, such as the Sun, a candle flame or a torch bulb.
Name two natural light sources.
The Sun and stars (also acceptable: lightning, fireflies, glow-worms).
Answer: The Sun and stars (also acceptable: lightning, fireflies, glow-worms).
- Saying the Moon is a light source The Moon does not make its own light — it reflects sunlight towards us.
- Thinking shadows can appear on the same side as the light A shadow always falls opposite the light source, where the light is blocked.
Practice
No — a mirror reflects light from a real source; it does not produce light itself.
Glass is transparent, so light passes straight through instead of being blocked.
Light travels in straight lines and cannot bend around the corner to reach your eyes.
At midday the Sun is high overhead so light comes almost straight down; in the evening the Sun is low, so your body blocks rays at a shallow angle and the shadow stretches out.
Quick check
Which of these best defines "light source"?
You move a toy further from a lamp. What happens to its shadow on the wall?
- Sources of Light: naming natural and artificial light sources, from the Sun to light bulbs.
- Shadows form when light is blocked: Stand in sunshine and your body blocks the Sun's rays, leaving a dark patch — your shadow — on the ground behind you.
- shadow: The dark shape formed when an object blocks light from reaching a surface.
- Watch out for: saying the Moon is a light source