In vacum, to travel distance d, light takes time t and in medium to travel distance 5d, it takes time T. The critical angle of the medium is

Options

A. `sin^(-1)((5T)/(t))`
B. `sin^(-1)((5T)/(3t))`
C. `sin^(-1)((5T)/(T))`
D. `sin^(-1)((3t)/(5T))`

Answer

C

Explanation

In vacuum, `c=d/t`
In medium, `v=(5d)/(T)`
As refractive index, `mu=(c )/(v)=(d//t)/(5d//T)=(T)/(5t)`
Also, `sinC=(1)/(mu) (therefore "C is critical angle")`
`therefore C=sin^(-1)[(5t)/(T)]`