# Propagation of light as wave

• utkarsh009
In summary, classical waves are a result of physical particles, while light is a wave that does not need a physical medium to travel. Classical waves can be seen as similar to how light behaves, such as interference and having certain aspects that are described using math similar to waves. However, light is still a particle that has momentum and energy that can only be absorbed or emitted in discrete quanta, the photon.

#### utkarsh009

huy there! everyone says that light has wave particle duality. it means light is a wave and also consists of a particle. now, wave is a disturbance in a medium. but, we know that light can travel without a medium. then why do we say it is a wave? (i know that it is a non mechanical wave then why do we define wave as a disturbance in a medium if it can be non-mechanical?) also light is a transverse wave. in this particles of medium move up and down about their normal positions. which are the particles that move up and down when light travels in space?

I think a better way of looking at it is to say that light acts as a wave or as a particle depending on what observations you do to it. For example, in the photoelectric effect, light is "acting" like a particle. However, in the double slit experiment light is "acting" like a wave in part of it, and then a particle in another part. Look it up on wikipedia for more info.

Classical waves, such as sound and water waves, are a result of a large amount of physical particles acting in a certain way. Light isn't like this. The only reason we call it a wave is that some of the results of our experiments are strikingly similar to what a classical wave would do, such as interference that we see in the double slit experiment. Also certain aspects of light can be described using math that is similar to describing waves, such as frequency and wavelength. However we still find that light acts like a particle and has momentum and a specific amount of energy that can only be absorbed or emitted in discrete quanta, AKA the photon, a particle.

Wave is a periodic disturbance in space which transfer energy. Any moving particles can be seen as wave packets since it alters space for a moment and transfer mass.

thanks for replying and explaining. :-)

## 1. What is the nature of light?

Light is a form of electromagnetic radiation that exhibits wave-like behavior. This means that it has properties of both a particle and a wave.

## 2. How does light propagate as a wave?

Light propagates as a transverse wave, meaning that it vibrates perpendicular to the direction of its motion. This allows light to travel through a vacuum or a medium, such as air or water.

## 3. What is the speed of light?

The speed of light in a vacuum is approximately 3 x 10^8 meters per second. This is a fundamental constant in physics and is denoted by the symbol c.

## 4. How does light interact with matter?

When light encounters matter, it can be absorbed, reflected, or transmitted. The interaction between light and matter is dependent on the properties of both the light and the material it is passing through.

## 5. Can light be polarized?

Yes, light can be polarized, meaning that its electric and magnetic fields are oriented in a specific direction. This can occur naturally or can be artificially induced, and is important in various applications such as 3D glasses or polarized sunglasses.