Plz solve question no. 20 and question no.22

Plz solve question no. 20 and question no.22 Derive the relation Light : Reflection and Refra gle 60L on the horizontal mirror becomes vertical after two successive ray diagram for the event. (0 is angle between plane mirrors) focal length f. magnification m and object distance u for a concave mirror. 14, 15. 16 17. 8, 19, 20. 21. A candle is held 3 cm away from a concave mirror of radius of curvature 24 cm. What will be the distance of image from mirror? Calculate the speed of light in (i) glass (ii) water. Refractive index of glass is 1.5 and water is 1,33. (Take speed of light in air or vacuum. c 3 x 108 m/s) An object of height 2.0 cm is placed perpendicular to the principal axis of a concave lens of focal length 12 cm. Find the height of the image, if the object is placed at a distance of 8.0 cm from the lens. A thin lens forms image of intensity l. If the central part of the lens of diameter half the diameter of lens is black polished, then what will be the intensity of image formed by the remaining part? A scientist claims that a ray initially parallel to the principal axis, after reflection from concave mirror passes through the pole. Is it possible? If not, why? If yes, then under what condition? Explain. The focal length Of a convex lens is f. An object is placed at a distance x from its first focal point. Find the ratio of the distance of the real image to that of the object from the pole. A plane mirror is placed at a distance 12.5 cm from focus Of a concave mirror of radius of curvature cm. Find where an object can be placed between the two mirrors, so that the first image in both the mirrors coincide. Explain why does a swimming pool appear shallower than it actually is. Obtain an expression for the normal displacement of an object immersed in water. 22. Deduce the expression f — for convex mirror. 23 When an object is placed at a distance Of 60 cm from a convex mirroq the magnification produceüs — 2. Where should the object be placed to get a magnification of — ?