WAVE PARTICLE DUALITY OF LIGHT: SUMMARISED - PART ONE

Source: commons.wikimedia.org

Light is undoubtedly a type of wave and at the same time, it still exhibits properties that only a particle would exhibit. Now the issue is why?

First lets discuss on what properties makes light a wave.

LIGHT AS A WAVE

Light is a wave, it exhibits all the known properties of waves. From the first to the fifth. Now let us take a quick view through all of these wave-like properties and see the cases where light exhibits them...

1. Refection
probably the most common and explains how we see our images in a mirror.

2. Refraction
the bending of light rays. It explains why a light bends when it changes medium; why a straw appears broken in a clear glass of water and even extends to apparent depth.

3. Interference:
When two identical waves meet in the same medium, they interact with each other in order to strengthen themselves(Constructive) or to destroy(destructive) themselves. This exhibits this too like other waves.

4. Diffraction

Single slit Diffraction of Light
(Source: cronodon.com, 2013. Image was also edited)

Diffraction is the bending of waves when they pass through an opening lower than their wavelength. This is applicable in reading a CD or DVD disc.
Read more on interference and Diffraction here.


5.Polarization
Polarization is the change in the plan of oscillation of light waves. Its occurrence in nature makes the sky appear blue and is used in many other fields.

Light isn't just a wave, it has a family called ELECTROMAGNETIC WAVES it has all their properties. From their common velocity (c= 2.997 x 10^8m/s) to a perfect place in their frequency(400-790THz) and wavelength(380-750nm) spectrum.

Light in the Electromagnetic Spectrum
Source: www.itseducation.asia

LIGHT AS A PARTICLE

Wow, now light is a particle too. It has properties that only particles would exhibit.

1. Light supports the view that its is a stream of particles called PHOTONS.
This was postulated by Albert Einstein. Photons are the smallest unit of radiant energy. They are like small particles that makes up light waves.
-The greater the number of photons, the greater the intensity of light.
-The higher the frequency of oscillation of the photons, the more energy they carry.
This energy is given as E=hf;
where, E = Energy of oscillation of photon
h = Planck's constant (6.63 × 10^-34 m2kg/s)
f = frequency of oscillation.

2.It obeys the law of conservation of momentum, in fact, it can knock off other 'particles' and transfer energy to them.
This is seen in an phenomenon known as the Compton effect.

The Compton Effect

Source: whs.wsd.wednet.edu

This is seen in cases where light rays are used to liberate electrons from the surface of metals (Read Photo Electric Effect). It is noticed that the energy the electrons, leaving the surface of the metal possesses, approximately equal to the energy of the colliding photon. This means that, the laws of conservation of momentum and energy has been obeyed.

Continue to WAVE PARTICLE DUALITY OF LIGHT: SUMMARIZED - PART TWO