Question

A ray reflected successively from two plane mirrors incline at a certain angle undergoes a deviation of `240^@`. Then the number of images observable is
A. 3
B. 5
C. 7
D. 9

Answer 1

Correct Answer - B
`delta=360^@-2theta`
`theta:` angle between two mirrors
`delta:` total angle of deviation after two reflection
`240^@=360^@-2thetaimpliestheta=60^@`
`x=(360^@)/(theta)=(360^@)/(60)=6` (even)
Number of images, `n=x-1=6-1=5`