Car B overtakes another car A at a relative speed of 40 m/s. How fast will the image of car B appear to move in a convex mirror of focal length 10 cm fitted in car A, when car B is 1.9 m away from car A?

The magnifying power of an astronomical telescope in normal adjustment is 10 and the focal length of its eyepiece is 20 cm. The focal length of its objective lens will be:

If the speed of light is 2.12 × 108 m/s inside the medium of an equilateral prism, find the angle of minimum deviation (δm). (Take speed of light in vacuum c = 3 × 108 m/s, sin 45° = 0.707)