please explain with diagram principal section of a prism at mark the principal section in your diagram

Any section of prism, perpendicular to refracting edge is called principal section of prism.

ABC shows a principal section of an equilateral prism, such that A is the angle of prism. The ray GH is called emergent ray. The angle between emergent ray GH and normal GM is called angle of emergence (e).

EF = incident ray

i = angle of incidence = angle between incident ray and normal.

e = angle of emergence = angle between emergent ray and normal.

r1 = angle of refraction = angle between refracted ray and normal.

r2 = angle of incident = angle between incident ray on the other face and normal.

The angle between incident ray and the emergent ray is called angle of deviation. It is represented by letter.

The value of angle of deviation produced by the prism depends on —

  1. Angle of incidence

  2. Refractive index of material.

  3. Colour or wavelength of incident light.

  4. Angle of the prism.

 

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Definition of PRINCIPAL SECTION

1
: a plane passing through the optical axis of a crystal; specif: the principal plane that contains either the wave normal or the ray of light under discussion
2
: a plane perpendicular to the edge of an optical prism.

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