Why does a ray of light passing through the glass slab not show dispersion?

Answer 1

White light is actually a combination of all of the colors of all of the rainbow. It splits in a prism because the prism can pick up the differences. However, it will not in a glass slab because the slab is smooth and will not reflect all of the different colors of light.

Answer 2

Actually a glass slab is made up of two triangular prisms placed inverted to one another. So dispersion taking place by the first prism is counter acted by the inverted prism and hence no dispersion is seen on a whole

Answer 3

Because the entry and exit surfaces are parallel. The dispersion in a prism

is due to the non-zero angle between the entry and exit surfaces, so that

the angles of incidence upon entry and exit are not equal.

Answer 4

I presume you mean a rectangular glass block. Here the light is refracted one way when it enters the block, and the opposite way when it emerges from the parallel opposite side. That is why the emergent ray is parallel to the incident ray, but shifted over.Some dispersion does occur at the first interface, because the blue wavelengths are refracted more than the red. (Blue bends best). However this is undone by the second refraction. In other words, it's a function of the geometry of the block. In a sixty degree prism, the angle at which the internal ray hits the second face is such that the refraction is in the same direction as the first one, so that the dispersion effect is magnified. Even so, you have to get the angle of incidence sufficiently steep to make the dispersion large enough to see a spectrum. You can actually see these phenomena if you have a pure white light source, sufficient shading and good quality glass. In the laboratory we often demonstrate optics phenomena by using a ray box and, certainly in schools, plastic blocks. Most ray boxes give a very yellow light which is short of the blue wavelengths, so arranging for bright sunlight to pass through a slit gives better results.

Answer 5

A glass slab does not show dispersion when light passes through it because the dispersion effect is usually minimal in materials with low refractive index, like glass. Dispersion occurs when different colors of light travel at different speeds through a medium, causing them to separate. In glass, the dispersion is small due to its relatively low refractive index, resulting in the colors of light staying relatively well-aligned.

Answer 6

glass prism doesn't disperse white light but disperse vibgyor because of refraction and internal reflection

Answer 7

The refractive index of prism is very high but its very low in glass slab, in glass slab the dispersion occurs but its very less, so is not visible.