$A$ thin prism $P_1$ with angle $4^{\circ}$ made of glass having refractive index $1.54$ is combined with another thin prism $P_2$ made of glass having refractive index $1.72$ to produce dispersion without deviation. The angle of the prism $P_2$ in degrees is:

The prism angle of a prism is $40^{\circ}$. $A$ light ray is incident at $38^{\circ}$ and undergoes minimum deviation. The angle of minimum deviation is ........$^{\circ}$.

$A$ ray of light is incident on a $60^{\circ}$ prism at the minimum deviation position. The angle of refraction at the first face (i.e.,incident face) of the prism is.......$^{\circ}$

$A$ combination of two prisms,one of flint glass and another of crown glass,produces dispersion without deviation. The angle of the flint glass prism is $15^o$. The angle of the crown glass prism and the net angular dispersion will be respectively: (Given: for crown glass $\mu = 1.52, \omega = 0.02$; for flint glass $\mu = 1.65, \omega = 0.03$). (in $^o$)

The angles of incidence and emergence of a light ray passing through a prism of angle $A$ are $i$ and $e$ respectively. The total deviation produced by the prism is

$A$ thin prism $P_1$ with an angle $6^{\circ}$ and made of glass of refractive index $1.54$ is combined with another prism $P_2$ made from glass of refractive index $1.72$ to produce dispersion without average deviation. The angle of prism $P_2$ is $........{}^{\circ}$