Suppose at the boundary of two optical media,of different refractive indices a mirror is kept perpendicular to surface of the boundary.If a ray of light travels through one of the media and then strikes the mirror at the boundary,then will the reflected ray passing through the other media , follow the laws of reflection?? Is A=B?
The "reflected ray" will follow both the law of reflection and the law of refraction (i.e., Snell's law). It may be simpler to analyze the situation if you consider the incident ray actually hitting a point on the mirror slightly above the A-B interface. In this case, the incident ray reflects off the mirror with the same angle A, and then hits the A-B interface and then its angle is bent from an angle A to an angle B by Snell's law. You could also consider the case when the light beam is adjusted to hit a point below the A-B interface. In that case, the beam of light is first refracted from an angle A to a new angle B, and then bounces off the mirror with the same angle B. The bottom line is that you get the same answer regardless of whether the incident beam hits the A-B interface exactly at the point where it meets the mirror, or a little bit above or below that point.