Light wave or particle
Hello! Welcome back to our blog Simple Science. Today I’m
going to write something about light, what is light? Light is a form of energy
which can travel in absence of any medium. Or Light is an electromagnetic wave
having electric and magnetic field perpendicular to each other and both of them
is perpendicular to its path of propagation. Behaviour of light is one of the
most confusing question in the field of science and also it raised several
theories to describe its behaviour. I’m going to describe few of them.
First one is the Newton’s corpuscles theory
According to this theory, light is a particle having some
energy. This theory of light was able to describe the spectrum of light and
reflection of light. The colours of light are due to size difference of
corpuscles each size of the corpuscles is for each colour. However, this theory
was applicable somewhere but this theory can’t able to describe the refraction
of light. According to this theory when a light particle hit any surface then
some amount of energy gets absorbed by the surface and rest reflected by it.
And in terms of refraction this theory states that, when a light particle is
travelling in lighter medium and get incident on denser medium then it gets
attracted towards denser medium and due to which its speed increases in denser
medium. But actually, its opposite happens.
Huygens wave theory of light
This was the fourth wave theory of light. According to this
theory light travel in the form of wave which travels through a medium called
luminiferous ether or simply ether and this ether is present everywhere in this
universe. This theory also says that light wave is a longitudinal wave which
was not correct. But theory was able to describe why light travel at constant
speed in the space. Sound is a longitudinal wave which requires a medium to
propagate and it have two property (i) Frequency and (ii) Intensity which determine
by its source and third is its speed which is not determined by its source. The
speed of sound is determined by the medium through which it travel. If you
increase the volume of your speaker there will be no change in its speed. And same
thing is with light however it is blue or red or UV its speed will be constant
in a medium. I have another example, if you drop a 20-gm stone or a 20 kg in a
pond the speed of the disturbance will be constant which will be determined by
the water not by the cause of disturbance (i.e. stone). This theory has
explained everything about the light but there was no evidence of the ether. And
finally, the idea of ether was collapsed.
The dual nature of light.
Light shows wave as well as particle nature when we observe
it. When we are observing its wave nature at that time its particle nature
collapse and when we are observing its particle nature at that time its wave
nature collapse. In photoelectric effect light observed as rain of particles or
rain of photons while in double slit experiment it starts behaving like wave.
Light has exposed great mysteries of this universe since physicist
started understanding it and there is no doubt it can helps us a lot if we observe
it more deeply. It can open the path of quantum world, time machine and can
exposed this whole cosmos.
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And don’t forget to share with your family and friends.
Read our older posts on light:-
(i) What is light?
