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Question: Answered & Verified by Expert
A ray of light AO in vacuum is incident on a glass slab at angle 60° and refracted at angle 30° along OB as shown in the figure. The optical path length of light ray from A to B is:
PhysicsRay OpticsJEE MainJEE Main 2019 (10 Apr Shift 1)
Options:
  • A 23a+2b
  • B 2a+2b
  • C 2a+2b3
  • D 2a+2b3
Solution:
2434 Upvotes Verified Answer
The correct answer is: 2a+2b

Optical path length =OA+μOB
=acos60o+μbcos30o
=2a+μ2b3
From Snell’s law,
sin60o=μsin30o
μ=3
Optical path length =2a+32b3
=2a+b

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