A small candle, 2.5 cm in size is placed at 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image?
(1) 54 cm away from the mirror.
(2) 64 cm towards the mirror.
(3) 40 cm away from the mirror.
(4) 44 cm towards the mirror.
A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. What is the magnification?
A Cassegrain telescope uses two mirrors as shown in the figure. Such a telescope is built with the mirrors 20 mm apart. If the radius of curvature of the large mirror is 220 mm and the small mirror is 140 mm, where will the final image of an object at infinity be?
(1) 315 mm away from the secondary mirror.
(2) 315 mm towards the secondary mirror.
(3) 313 mm away from the secondary mirror.
(4) 313 mm towards the secondary mirror.