An equilateral prism is made of glass of refractive index 1.5. Calculate the angles of minimum and maximum deviation. Given:
`A=60^@, mu=1.5, sin48.6^@=(3)/(4), sin41.8^@=(3)/(2), sin27.9^@=(3)/(2)sin18.2`

Explanation

At minimum diviation,
`2r =A or r=30^@`
Also, `mu=(sin(i))/(sin(r))`
Substituting the values, we get
`1.5=(sin(i))/(sin(30)) or i=48.6^@`
The angle of deviation, `delta=2i-A=37.2^@`
At maximum deviation:
`A=60^@,mu=1.5 andi_(1)=90^@`
Since `mu=(sin(i_(1)))/(sin(r_(2)))` , we get ` 1.5=(sin(90))/(sin(r_(1)))`
or `r_(1)=41.8^@`
But `r_(1)+r_(2)=A`, therefore, `r_(2)=18.2^@`
Once again, `mu=(sin(i_(2)))/(sin(r_(2)))`
`:. 1.5=(sin(i_(2)))/(sin(18.2))` or `i_(2)=27.9^@`
Therefore, the angle of deviation,
`delta=i_(1)+i_(2)-A=57.9^@`