Light travels in straight lines from a source. We see a light source when its light goes straight into our eyes. We see other objects because light from a source bounces off them and then travels into our eyes. That is why we cannot see in the dark: no light is bouncing off anything.
A mirror reflects light very well, so it gives a clear image. A periscope uses two mirrors to see over a wall. The part of the eye that lets light in is the pupil, the black circle in the middle. In bright light it gets smaller to protect the eye; in dim light it gets bigger to let more light in.
Worked example
Explain how you see a book on a table.
- Light travels from the lamp to the book.
- Light reflects off the book.
Answer:The reflected light travels in a straight line into your eyes.
Key words
- straight line
- the way light travels
- mirror
- a very smooth, shiny surface that reflects light clearly
- pupil
- the hole in the eye that lets light in
- periscope
- a tube with two mirrors for seeing over things
Practise this
New questions every time.
NGSS-referenced: 4-PS4-2