Two mirrors at an angle `theta^(@)` produce 5 images of a point. The number of images produced when `theta` is decreased to `theta^(@) - 30^(@)` is

Options

A. 9
B. 10
C. 11
D. 12

Answer

C

Explanation

Number of images `=(360^@)/theta-1`,
where `theta` is in degrees
`:.5=(360^0)/theta-1 or =(360^@)/theta=60^@`
New angles,
`theta=theta-30^@=60^@-30^@=30^@`
Number of images
`=(360^@)/theta=-1=11`