What is the position of the image when an object is placed at a distance of 20 cm from a concave mirror of focal length 20 cm ?
At what distance from a concave mirror of focal length 10 cm should an object be placed so that : (a) its real image is formed 20 cm from the mirror ? (b) its virtual image is formed 20 cm from the mirror ?
An object is placed at a distance of 20 cm in front of a concave lens of focal length 20 cm. Find :
(a) the position of image, and
(b) the magnification of image.