JEE Main & Advanced
Sample Paper
JEE Main Sample Paper-5
question_answer
Two mirrors, placed perpendicularly form two sides of a vessel filled with water. A light ray is incident on the water surface at an angle\[\alpha \]and emerges at an angle\[\beta \]after getting reflected from both the mirrors inside. The relation between\[\alpha \]and\[\beta \]is expressed as
A) \[\alpha =\beta \]
B) \[\alpha >\beta \]
C) \[\alpha <\beta \]
D) All are possible depending upon\[\alpha \]
Correct Answer:
A
Solution :
From above diagram, we have \[90-{{\theta }_{1}}+90-\theta +45{}^\circ +90+{{\theta }_{2}}=180{}^\circ \] \[\Rightarrow \]\[{{\theta }_{1}}+\theta =45{}^\circ ={{\theta }_{1}}+{{\theta }_{2}}\] \[\Rightarrow \]\[{{\theta }_{1}}={{\theta }_{2}}\] \[\Rightarrow \]\[\alpha =\beta \]