Define lateral magnification.

$(a)$ The refractive index of diamond is $2.42$. What is the meaning of this statement?
$(b)$ Redraw the diagram given below in your answer book and complete the path of the ray.
$(c)$ What is the difference between virtual images produced by concave and convex mirrors?
$(d)$ What does the negative sign in the value of magnification produced by a mirror indicate about an image?

When an object is placed between the principal focus $(F)$ and the center of curvature $(C)$ of a concave mirror,what kind of image is formed?

What is the relation between the radius of curvature $(R)$ and the focal length $(f)$ of a spherical mirror?

Refractive index of diamond with respect to glass is $1.6$ and absolute refractive index of glass is $1.5$. Find out the absolute refractive index of diamond.

As the velocity of light increases,the refractive index of the medium decreases. Light enters from air to water having a refractive index of $4/3$. Find the speed of light in water. The speed of light in vacuum is $3 \times 10^{8} \text{ m s}^{-1}$.