An object is kept on the principal axis of a convex mirror of focal length $10 \mathrm{cm}$ at a distance of $10 \mathrm{cm}$ from the pole. The object starts moving at a velocity $20 \mathrm{mm} {\sec }^{-1}$ towards the mirror at an angle $30°$ with the principal axis. What will be the speed of its image and direction with the principal axis at that instant.

A particle is moving towards a fixed convex mirror. The image also moves. If $V_{\mathrm{i}}=$speed of image and $V_{\mathrm{O}}=$speed of the object, then

A parallel beam of light is incident normally on the flat surface of a hemisphere of radius $6 \mathrm{cm}$ and refractive index $1.5$, placed in the air as shown in the figure $\left(\mathrm{i}\right)$. Assume paraxial ray approximation.

A ray is an incident on a refracting surface of refractive index $\mu$ at an angle of incidence $i$ and the corresponding angle of refraction is $r$. The deviation of the ray after refraction is given by $\delta =i-r$. Then, one may conclude that

A convex lens and concave lens are kept in contact and the combination is used for the formation of the image of a body by keeping it at different places on the principal axis. The image formed by this combination of lenses can be

A ray of light travelling in water is incident on its surface open to air. The angle of incidence is $\theta$, which is less than the critical angle. Then, there will be