question_answer

A point source has been placed as shown in the figure. What is the length on the screen that will receive reflected light from the mirror?

A) 2H

B) 3H       

C) H

D) None of these  

Correct Answer: A

Solution :

[a] In \[\Delta \,ABD,\frac{3D}{3H}=\tan 45{}^\circ \text{ or }BD=3H\] And in \[\Delta A'BC,\frac{BC}{2H}=\tan \theta =\frac{1}{2}\text{ or }BC=H\] \[\text{Now, }y=BD-BC=3H-H=2H.\]