Bsc 4th semester physics notes CBCS

1) What is diffraction of light ? Who discovered, what are factors on which it depends.

==> The bending of light near the edges of the obstacle and encroachment into the reason of geometrical shadow is called diffraction of light.

• This was 1st observed by Geimeld in 1668. The diffraction of light is depends on

1) wavelength of light

2) width of slit or size of slit

2) explain huygen's wave theory.

==> The light travels in the form of waves on the longitudinal mechanical wave was 1st observed by huygen. Every point on the luminous body is the source of disturbance hence light travels in the form of wave for the propogation of light wave . Huygen assured hypotypical medium is called ether.

* It has high elasticity, low density, weightlessness and invisible

Light from point source "S" travels in the form of waves with the velocity "C" after the time "t" . All the particles of the ether medium lying on the surface xy is called primary wavefront and it's radius become ct

Spherical wavefront

3) what is wavefront of the wave.

==> The locus of the all the points lying on the surface having same phase is called wavefront of the wave.

4) what are spherical, cylindrical and plane wavefront.

==> Spherical : the wavefront produced at the smaller distance from the point source is called spherical wavefront.

Cylindrical : the wavefront produced at the smaller distance from the linear source is called cylindrical wavefront.

Plane : the wavefront produced at the larger distance either by the point source or linear source is called plane wavefront.