When prism is kept inside the water then why angle of incidence = angle of emergence?

Question

10 ptsssssss please

Answer 1

Are you talking about refraction? No it isn't always true! It will only happen if and only if:

1. the angle of incidence is normal to the surface of the prism. (that makes sintheta = 0, therefore any change in n will not bend the light)

2. the index of refraction of the prism is equal to the index of refraction of the water (with that, there's no reason for the light to bend, since its speed won't change at all as it transfer from water to the prism)

Answer 2

Its the property of prism that when it is kept in water then angle of incidence = angle of emergence.

Answer 3

The answer that says θ1 = 0 or N of prism = N of water is too restrictive (if you're referring to a rectangular prism) or doesn't apply (if you're referring to a triangular prism) because it assumes the faces are parallel.

For any rectangular prism in any medium, Snell's law says that any incident light ray will have equal incident and exit angles. This is because it doesn't distinguish between types of transition; the light can be going from high N to low N or the opposite.

If you are referring to a triangular prism you may be trying to describe a specific experimental condition, but the actual angles must be given. If you check the ref., the equal-angles case is also the minimum-path-change case, for which a formula is given. This can be solved for N when the prism is in air/vacuum. Snell's law then says that 1(N of vacuum)/N = 1.33 (N of water)/Np (the actual prism's IR).