Two plane mirrors AB and CD are placed at right angles to one another. A ray of light PQ hits AB at Q making an angle of `45^@` as shown in the diagram. This ray will be reflected from mirror CD at an angle

Options

A. `20^@`
B. `35^@`
C. `45^@`
D. `60^@`

Answer

C

Explanation

Since QS is normal to the mirror AB.

`therefore anglei_1=45^@`, Also `angler_1=45^@`
In `triangleCQR, angleC=90^@,angleCQR=45^@ therefore angleCRQ=45^@` [`because` Sum of all the three angles in triangle is `180^@` ]
Hence , `anglei_2=45^@` [ `because` TR is the normal to the mirror CD]
`therefore angler_2=45^@`