How we see
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Evolution and inheritance
Light
Explainer Video
Summary
How we see
In a nutshell
You can see objects because they are a source and pass light directly into the eyes, or because they reflect light from a source into your eyes.
How objects are seen
There are two situations in which we can see the objects around us. These are:
- The object is a source and passes the light directly into the eyes.
- The object is not a source, but it reflects light from another source (such as the Sun) and into the eyes.
A light source is an object which produces light. This means that if an object is not a source, then it does not produce its own light.
Example:
A source is a fire or a glow stick. Bike reflectors are not a source of light.
The eye
The eye is very important for focusing light in order to see. Objects are seen because they produce or reflect light that travels into the eye. The lens in the eye focuses the light onto the retina.
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Once the light enters the eye, a message is sent to the brain via the optic nerve, and the brain interprets what it is seeing.
Curiosity: Someone may need glasses to see because the light doesn't focus properly on the retina.
FAQs - Frequently Asked Questions
What is a light source?
A light source is an object that produces its own light, for example the Sun or a torch.
How do we see objects?
Objects are seen because they produce or reflect light that travels into the eye.
What happens once light enters the eye?
Once light enters the eye, a message is sent to the brain, and the brain interprets what it is seeing.