Theory of Light
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| Light |
- Newton’s Corpuscular
theory
- Huygens’s wave theory
- Maxwell’s
electromagnetic wave theory &
- Plunk’s quantum
theory
Newton’s Corpuscular
theory:
A source of light continuously emits tiny elastic particles called
Corpuscle. The particles/Corpuscles moves with high velocity as that of light
and get scattered in all direction of light. This theory says the velocity of
light is changed with the change in density of medium. This theory can explain
three major properties of light are reflection, refraction and rectilinear
propagation. This theory also says the color of light depends on the size of
corpuscles. This theory has some drawbacks which are given below…….
- This theory cannot
explain Diffraction, Dispersion, and Polarization etc.
- According to this
theory the velocity of light in denser medium is greater than the rare medium,
but later it proves wrong.
- This theory assumed
that the source of light loses mass as it emits particles, but not such
determent that the mass loose.
- As per this theory
the velocity light is changed if the temperature is changed. But later it
proves that light is independent of temperature.
Huygens’s wave theory:
The locus of all medium particles vibrating in the same phase is called a wave
front. Each point in a source of light sends out waves in the all directions in
a hypothetical medium called ether. Ether was assumed to be a continuous medium
which provides all spaces having large elasticity and extremely low density
which is homogeneous and isotropic. This theory says the waves of light is
mechanical and transverse in nature. It can explain the phenomena are
reflection, refraction, interference and diffraction. This theory agreed with
the previous theory in the velocity of light dependent on the density of the
medium and the color of light depend on the length of wave.
 |
| Ether |
The drawbacks are…
- There is no existence
of medium “Ether”.
- It fails to explain
the electromagnetic effect, polarization and Compton Effect.
- It fails to explain
why light has no longitudinal component.
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