Optics Question 955

Question: It is found that all electromagnetic signals sent from A towards B reach point C. The speed of electromagnetic signals in glass cannot be:

Options:

A) 1.0×108m/s

B) 2.4×108m/s

C) 2×107m/s

D) 4×107m/s

Show Answer

Answer:

Correct Answer: A

Solution:

[a] This is a case of total internal reflection.

θ>θc(=sin11μ) 1μ<sinθ

1μ<sin45 μ>1/sin45

μ>2 As v=cμ v<c2=3×1082 v<2.1×108

only (2) is not possible.



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