When a glass prism of refracting angle `60^(@)` is immersed in a liquid its angle of minimum deviation is `30^(@)`. The critical angle of glass with respect to the liquid medium is

Options

A. `42^@`
B. `45^@`
C. `50^@`
D. `52^@`

Answer

B

Explanation

`._lmu_g=(sin((A+delta_m)/(2)))/(sin(A/2))=(sin((60+30)/(2)))/(sin(60/2))=(sin45^@)/(sin30^@)`
`=(1//sqrt2)/(1//2)=sqrt2`
`._amu_gsinC=._amu_lsin90^@`
`sinC=(._amu_l)/(._amu_g)=(1)/(._lmu_g)=1/sqrt2impliesC=45^@`