# Angle of prism (mu = 1.5) is 30degree when monochromatic light is incident perpendicular to surface at what angle will it deviate?  a) 18degree 36minute b) 22degree 38minutec) 18degreed) 22degree 1minute

Arun
25758 Points
2 years ago
Dear student

We know that
n = sin i /sinr

1.5 = sin i / sin 30°

sin i = 0.75

On solving i = 18°36'

Hence Option A is correct.
Vikas TU
14149 Points
2 years ago
Dear student
The above explanation is very much incorrect , I feel sorry for that,
You can use the formula $\frac{n(prism)}{n(air)}$
This is given by {Sin(A+dm)/2} /  Sin(A/2) = $\frac{n(prism)}{n(air)}$
Put all the values in it A = 30 , and dm is deviation here,
So , the angle of deviation will comw out to be 15 degree and 16 minute , The ans given in the option is not matching ,
Ans is matching when tou will take (A+dm)/2 , it is 22 degree 83 minute.
Hope this helps
Good Luck