What is Light? | Definition, Types, Formula & Examples

What is Light made of?

Light has no mass and is not really considered matter. So does it even exist? Of course it is! We cannot live without light. Today, scientists say that light is a form of energy made up of photons. Light is unique in that it behaves both as a particle and as a wave.

Why does Light go through some things and not others?

Depending on the type of matter it comes into contact with, light behaves differently. Sometimes light travels directly through matter, as with air or water. This type of material is called transparent. Other objects completely reflect light, such as an animal or a book. These objects are said to be non-transparent. The third type of object does a bit of both and tends to scatter light. These objects are called fuzzy objects.

How Light helps us to survive

Without sunlight, our world would be a dark and dead place. Sunlight doesn’t just help us see (which is great too). Sunlight keeps the Earth warm, so it’s not just a frozen ball in space. It is also a major component of photosynthesis, which is how most plants on Earth grow and obtain nutrients. Sunlight is a source of energy as well as a source of vitamin D for humans.

What is the speed of Light?

Light travels at the fastest known speed in the universe. Nothing travels faster (or even close to) the speed of light. In a vacuum, where nothing slows it down, light travels at 300,000 km/s! Well, that’s fast! When light passes through matter, such as air or water, it slows down a bit, but is still pretty fast.

To help you visualize the speed of light, we will give some examples. The Sun is nearly 93 million km from Earth. It takes about 8 minutes for light to travel from the Sun to the Earth. It takes about 1.3 seconds for light to travel from the Moon to Earth.

Refraction

Normally, light travels in a straight line called a ray, however, when it passes through transparent materials, such as water or glass, the light will be bent or rotated. This is because different materials or media have different qualities. In any type of medium, whether air, water or glass, the wavelength of light will change, but the frequency will not. As a result, the direction and speed of the traveling light wave will change and the light will be bent or redirected.

An example of a refraction is a prism. Prisms are unique in that each color of light is refracted at a different angle. Therefore, it can take white light from the Sun and emit light of different colors.