refraction problem?

Question

why is it so that in refr. through glass slab the ray bends as soon as it enters glass and again when it goes out but in lens it bends only at optical centre?

Answer 1

The same phenomena occurs with curved lenses. In a lens the light doesn't only bend at the optical center, quite the contrary, but the light bent by the len's curvature is focused at its optical center .

Let me explain. As light passes from one transparent medium to another, it changes speed, and bends. How much this happens depends on the refractive index of the mediums and the angle between the light ray and the line perpendicular (normal) to the surface separating the two mediums (medium/medium interface).

All rays also reflect internally. This occurs in glass for instance as well as raindrops and other materials.

When light travels through a glass window, water or the curved glass of a lens, for example, its path is bent or refracted.

Eyeglass lenses and contact lenses are fabricated with precise curvatures that help offset flaws in our eye's optical system. These lenses intercept and bend light rays, such that they achieve a more precise point of focus on our eye's retina..

Answer 2

Its not that in a lens the light ray bends only at the optical centre. Sure in the ray diagrams its is shown this but actually here also light bends as soon as it enters the lens. Since the surface of the lens is curved it becomes difficult to show the bending of light at that point of time, keeping in mind the making of normal and all that stuff. Refraction takes place at the surface only. So dont get confused in case of a lens. It is just for the sake of making it easier to see that the bending is shown at the optical centre.

Answer 3

The first answer is correct; a non-normal light ray always bends at each transition between media with differing refractive indices. The single-bend representation of a lens is imprecise but reasonably good for thin lenses, and allows a simplification of the math ("thin-lens theory"). Many of these simplifications don't hold up for thick lenses, especially where there is a large angular deflection of an incident ray (e.g., near the edge of the lens). In that case each of the two refractions has to be separately accounted for.

Answer 4

Actually in a lens too, the light ray is refracted twice but the total refraction can be considered to take place at the secondary axis.

Hope this helps.

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Answer 5

Snell's regulation does paintings. This attitude is referred to as the Brewster attitude n1sin(A1)=n2sinA2 First, you have got bought the geometry of the beam but it surely offers you the perspective relative to the skin sinB=7.33/sqrt((6.forty four)^two+(7.33)^two) ==> B=forty eight.7 levels A1=ninety-forty eight.7=forty one.three Internal mirrored image begins to occur while A2=ninety levels. If we expect the fabric above the liquid is air and n2=a million we now have the next use of Snell's regulation x*sin(forty one.three)=a million*sin(ninety) ==>x=a million/sin(forty one.three)=a million.fifty two