WAVE FRONT, VARIOUS TYPES OF WAVE FRONT AND RAYS
• Wavefront
The locus of all the particles vibrating in the same phase is known as wavefront.
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• Types of wavefront
The shape of wavefront depends upon the shape of the light source originating that wavefront. Depending upon the shape of the source of light, wavefront are of three types.
1. Spherical Wavefront:
Shape of light source: Point source
Diagram of shape of wavefront:
Variation of amplitude with distance:
Variation of intensity with distance:
2. Cylindrical Wavefront:
Shape of light source: Linear or slit
Diagram of shape of wavefront:
Variation of amplitude with distance:
Variation of intensity with distance:
2. Plane Wavefront:
Shape of light source: Extended large source situated at very large distance
Diagram of shape of wavefront:
Variation of amplitude with distance:
      A = constant
Variation of intensity with distance:
      I = constant
CHARACTERISTIC OF WAVEFRONT
(a) The phase difference between various particles on the wavefront is zero.
(b) These wavefront travel with the speed of light in all directions in an isotropic medium.
(c) A point source of light always gives rise to a spherical wavefront in an isotropic medium.
(d) In an isotropic medium it travels with different velocities in different directions.
(e) Normal to the wavefront represents a ray of light.
(f) It always travels in the forward direction of the medium.
RAY OF LIGHT
The path of the light energy from one point to another is known as a ray of light.
(a) A line drawn at right angles to the wavefront is defined as a ray of light, which is shown by arrows in previous diagram of shape of wavefront.
(b) It represents the direction of propagation of light.
Questions
Q1) What is the shape of the wavefront when light is diverging from a point source? [1]
Ans.: Spherical
Q2) Draw a diagram to show cylindrical wavefront? [1]
Ans.: see above
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