Question

calculate speed of light in a medium whose critical angle is 45

Answer 1

n = c/v 

where n = index of refraction 
c = speed of light in vacuum 
v = speed of light in medium

speed of light in vacuum = 3 x 10^8 m/s

n = i / sin(c) 

c  = critical angle 

so n =  1/ 1/ sqrt(2)

n = sqrt (2)...

sqrt (2) = 3x10^8 / v

v = 3x10^8 / sqrt (2)..