Distance light travels between reflections in a fiber

[sdoyle1]

Homework Statement

A ray of light enters a light fibre so that it hits the side at an angle of 16° with the long axis of the fiber, . Calculate the distance the light ray travels between successive reflections off the side of the fibre. Assume that the fibre is 1.03x10-4 m in diameter.

Homework Equations

I don't really know where to start I think you need to use n=1.00 for air but I'm not really sure

The Attempt at a Solution

Again, I'm not sure what to do.. Should we use snell's law? Not sure how to relate this back to the distance the light travels.. or should it be the mirror equation? 1/f=1/p+1/q

 

[ideasrule]

Draw out the path of the light ray. You don't need to use any optics equations; simple trigonometry would do.