In a plane mirror,the distance between the image and the mirror is the same as the distance between the object and the mirror.

$(a)$ 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 at the center of curvature $(C)$ in front of a concave mirror,what kind of image is formed?

If the angle of incidence on a plane mirror is $30^{\circ}$,what is the angle of reflection (in $^{\circ}$)?

What type of mirror is used to obtain a real image?

Find the focal length of a convex lens,if its power is $+2.0 \ D$. (in $m$)