Assertion : A total reflecting prism is used to erect the inverted image without deviation. Reason : Rays of light incident parallel to base of prism emerge out as parallel rays.

• Correct answer
  A

  If both assertion and reason are true and reason is the correct explanation of assertion
• B

  If both assertion and reason are true but reason is not the correct explanation of assertion
• C

  If assertion is true but reason is false
• D

  If both assertion and reason are false.

Solution

Beam of light incident on face $A B$, suffers refraction from air to glass and strikes the face $A C$ suffering total internal reflection. The beam now strikes the face $B C$ of the prism at an angle of incidence less than the critical angle hence it suffers refraction from glass to air and bends away from the normal. The beam emerges out parallel to the base. As a result of refraction, on emergence the rays are inverted.

Hence, the correct answer is option: 'A'.