Physics · Total internal reflection and its applications, magnification, power of a lens, combination of thin lenses in contact

A ray of light incidents normally on first face of the prism and the emergent ra

A ray of light incidents normally on first face of the prism and the emergent ray grazes the second surface. If \( A \) is the angle of the prism and \( C \) is its critical angle then the correct choice is:

  • A. \( A \)
  • B. \( A>C \)
  • C. \( A=C \)
  • D. \( A \geq C \)

Step-by-step solution

When light enters the prism normally, it does not deviate at the first surface. Inside the prism, it strikes the second surface at an angle equal to the prism angle A. For the emergent ray to graze the second surface, the angle of incidence at that surface must equal the critical angle C. Therefore, A = C.
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