# why do we get a case of real image image and virtual image only when the light rey passes through rarer to denser medium that too only in convex refracting  surface?why cant we gat real image in case of concave refracting surface or in case of convex refracting refracting surface when the light ray passes through denser medium to rarer medium? we always get a virtual image in this case,,,why?

SAGAR SINGH - IIT DELHI
878 Points
13 years ago

Dear student,

Whenever a ray of light from one transparent medium to another, it gets deviated from its original path while crossing the interface of the two media (except in case of normal incidence). This phenmenon of devition or bending of light rays from their original path while passing from one medium toanother is called refraction.

AB incident ray            BC refracted ray         NBN' Normal
i angle of incidence      r angle f refraction      KL interface

• If the refracted ray bends towards the normal with respect to the incident ray, then the second medium is said to be optically denser as compared to the first medium.

• If the refracted ray bends away from the normal, then the second medium is said to be (optically) as compared to the first medium.

LAWS OF REFRACTION

:

(i) The incident ray, there fracted ray and the normal to the refracting surface at the point of incidence, all lie in the same plane.

(ii)The ratio of sine of the angle of incidence to the sine of the angle of refraction is constant for any two given media

i.e.

= constant = 1µ

2

= Refractive index.

This is called Snell's law.

All the best.

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