List of top Physics Questions on Ray optics and optical instruments asked in BHU UET

A ray of light is incident on the surface of separation of a medium with the velocity oflight at an angle $45^{\circ}$ and is refracted in the medium at an angle $30^{\circ}$. What will be the velocity of light in the medium?

An equiconvex lens is cut into two halves along (i) $XOX'$ and (ii) $YOY'$ as shown in the figure. Let ${f, f', f'' }$be the focal lengths of the complete lens, of each half in case (i), and of each half in case (ii), respectively.

Choose the correct statement from the following

lf the focal length of the lens is $20\, cm$. what is the distance of the image from the lens in the following figure?