A monochromatic beam of light is incident at the interface of two materials of refracive index{n}_{1} and {n}_{2} as shown. If {n}_{1}>{n}_{2} and \\theta_{{c}} is the critical angle then which of the following statements is NOT true?

\\theta_{1}=\\theta_{3} for all values of \\theta_{1}.

\cos \\theta_{2} is imaginary for \\theta_{1}>\\theta_{{c}}

\cos \\theta_{2}=0 for \\theta_{1}=\\theta_{c}.

\cos \\theta_{3} is imaginary for \\theta_{1}=\\theta_{{c}}.

KVPY 2020-21 SB SX Exam Previous Papers

Question : 34 of 120

Marks: +1, -0

A monochromatic beam of light is incident at the interface of two materials of refracive index

{n}_{1}

and

{n}_{2}

as shown. If

{n}_{1}>{n}_{2}

and

\θ_{{c}}

is the critical angle then which of the following statements is NOT true?

Solution:

{n}_{1}>{n}_{2}

this means light is going from rarer to denser medium.
So

\θ_{2}

will always be less than

\θ_{1}

{n}_{2} \sin \θ_{1}={n}_{1} \sin \θ_{2}

\cos (\θ_{2})

will never be imaginary and also

\θ_{2}

can't be

90°

. In question incorrect options are asked.

\∴({B}, {C}, {D})

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