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### Hollow Prism Q and A

Question (one option correct type):

A beam of light passes through a hollow glass prism. Then,

A) the beam of light undergoes lesser but some dispersion compared to solid glass prism
B) the beam of light is totally internally reflected and does not come out through the opposite face
C) the beam of light does not undergo dispersion at all and comes out parallel to the incident ray
D) the beam of light undergoes angular deviation

Solution

When a ray enters glass slab from air and again goes away from the glass slab, the emerging ray is parallel to the incident ray. This means that ray 2 is parallel to ray 1. Further, ray 3 is parallel to ray 2. This means that ray 1 is parallel to ray 3.

### Sum of the coefficients in the expansion of $(x+y)^n$ ....
If the sum of the coefficients in the expansion of $(x+y)^n$ is 4096, then the greatest coefficient in the expansion is _ _ _ _ . Solution $C_0 + C_1 + C_2 + C_3 + ......................... + C_n =4096$ $\therefore 2^n = 4096 =2^{12}$ $\Rightarrow n = 12$ Greatest coefficient = ${}^{12}{C_6} = 924$