In the diagram,a prism of angle $30^o$ is used. $A$ ray $PQ$ is incident as shown. An emergent ray $RS$ emerges perpendicular to the second face. The angle of deviation is.....$^o$

By placing the prism in the minimum deviation position,the images of the spectrum:

In the visible region, the dispersive powers and the mean angular deviations for crown and flint glass prisms are $\omega, \omega^{\prime}$ and $d, d^{\prime}$ respectively. The condition for obtaining dispersion without deviation, when the two prisms are combined, is:

$A$ thin prism of angle $5^{\circ}$ is placed at a distance of $10\,cm$ from an object. What is the distance of the image from the object? (Given refractive index $\mu$ of prism $= 1.5$)

The angle of a prism is $A$. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence $2A$ on the first surface return back through the same path after suffering reflection at the silvered surface. The refractive index $\mu$ of the prism is:

For the angle of minimum deviation of a prism to be equal to its refracting angle,the prism must be made of a material whose refractive index is: