Why does white light split into different colours when passing through a prism but not when passing through a glass slab?
Because a prism has non-parallel sides
A glass slab has two parallel refracting faces. Light bends towards the normal as it enters and by exactly the same amount away from the normal as it leaves, so the emergent ray is parallel to the incident ray and every colour is displaced equally.
A prism has two refracting faces inclined to each other, so the second refraction adds to the first instead of cancelling it.
Each colour has its own refractive index in glass (violet the highest, red the lowest), so with non-parallel faces each colour emerges along a different direction and the beam spreads out into a spectrum.
Hence, the answer is because a prism has non-parallel sides.
Similar Questions
A ray of light enters a rectangular glass slab from air at an angle of 40 degrees to the normal. If the refractive index of glass with respect to air is 1.5 and the velocity of light in air is \(3 \times 10^{8}\) m/s, what is the velocity of light inside the glass slab?
What happens when white light passes through a glass prism?
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Important Questions from Refraction and Reflection
- How can you identify a concave and a convex mirror based on the direction of their reflecting surfaces?
- Stars appear to twinkle in the night sky because ______.
What type of image is always formed by a concave lens, no matter where the object is placed?
- Which of the following is NOT caused by atmospheric refraction?
- According to the sign convention, the height of an erect image formed by a mirror is taken as:
