Question

Two identical mirrors are placed in a hollow cylindrical tube as show in the figure. A light ray incident on one of the mirrors undergoes multiple reflections. In the length of each mirror is 3 m, and the velocity of light is `3xx10^(8)ms^(-1)`, then find the time raken by the light ray incident on the mirror to come out of the bollow cylinder.

Answer 1

`:."From" DeltaABC`
`1^(2)+1//2^(2)=AC^(2)`
`AC=(sqrt5)/(2)`
`:.` Distance travelled by the light ray.
`d=6xxsqrt5//2`
`(6sqrt5)/(2)`
`:.` Time taken `(d)/(v)=(2)/(3xx10^(8))=(6sqrt5xx10^(-8))/(6)s`
`:.` Time taken by light ray to reach point M is `sqrt5xx10^(-8)s`.