Question

What is light? How fast light travels.

Answer 1

Hint: Study about waves and its properties. Learn about different types of waves to answer the question. Light is a one type of wave that can travel without any help of any medium. It has the fastest possible velocity in the universe. Nothing can travel faster than the light.

Complete answer:
We know that there are mainly three types of waves.
Mechanical waves: These types of waves vibrate the particles of the medium to propagate along the medium.

Electromagnetic waves: this type of wave does not need any medium to propagate and the vibration of the wave is along the vertical direction means the wave vibrates perpendicular to the direction of propagation. Example-light. (This also falls under the example of transverse mechanical waves)

Matter waves: they are quantum mechanical waves. In quantum mechanics it says that the matter also behaves like particles and particles behave like waves. When matter behaves like waves it is called matter waves. Example- any quantum scale particle like electron, photon (it can only be explained by phenomena like -diffraction of electrons).

So, we can see that the light falls into the category of electromagnetic waves. The electromagnetic spectrum has a broader range of radiations from infrared to gamma rays. Light falls into the visible category of the spectrum. So, light is a one type of transverse electromagnetic radiation or wave. All the electromagnetic radiation travels at a speed of \[3 \times {10^8}{\text{m}}{{\text{s}}^{{\text{ - 1}}}}\] in vacuum or air. In other denser medium the velocity of it depends on the refractive index of the medium.

So, light also travels with a speed of \[3 \times {10^8}{\text{m}}{{\text{s}}^{{\text{ - 1}}}}\].

Note: Light has also matter properties. When it falls on an object it heats the objects by transferring energy. Then we consider the light as particles. This particle wave or matter waves of light in nature coexist at the same time. These particles of light are called photon particles.