Everything that is visible to us is emitting or reflecting light.
The Sun shining in the sky or street lamps glowing in the darkness.
Or light being reflected from trees, buildings, people, animals.
It's a form of energy that surrounds us.
Visible light makes up only a small part of the electromagnetic spectrum,
The range of electromagnetic radiation that fills our world.
Visible light is the only part that we can see naturally.
Light waves don't require molecules or atoms to transfer them.
If they did, our world would be a dark place, as almost all of our light comes from the Sun travelling through the near vacuum of space.
It travels at the speed of light, covering 150 million km in roughly eight minutes.
The speed of light is 3x108 m/s
The luminance or brightness is related to the amplitude or magnitude of the waves, and this can be affected by the distance from the source.
As light waves travel out from a source in straight lines, they spread out and become less concentrated – making the light appear dimmer.
This decreases the illuminance – how much light from a source hits a specific object or surface.
Light waves hitting objects are essential for our vision.
Although we can see the light emitted directly from sources we see most things because light is reflected off the surface, enters our eyes, and is then interpreted by our brain.
Whether natural or artificial, this form of energy is an important part of our lives allowing us to see, and providing vital energy for life on Earth.