Q17. An effective power of a combination of 5 identical convex lenses which are kept in contact along the principal axis is 25 D . Focal length of each of the convex lens is : (1) 20 cm (2) 50 cm (3) 500 cm (4) 25 cm
Q17. An effective power of a combination of 5 identical convex lenses which are kept in contact along the principal axis is 25 D . Focal length of each of the convex lens is :\\
(1) 20 cm\\
(2) 50 cm\\
(3) 500 cm\\
(4) 25 cm