An image of the sun is formed by a lens, of the focal length of 30 cm, on the metal surface of a photoelectric cell and a photoelectric current I is produced. The lens forming the image is then replaced by another of the same diameter but of focal length 15 cm. The photoelectric current in this case is

An image of the sun is formed on the metal surface of the photoelectric cell and it produces of current. The lens forming the image is then replaced by another of the same diameter but only half in focal length. a. What will be the effect on the photoelectric current? b. Is photoelectric emission possible at all frequencies ? c. If not give your explanation.

The image of the sun is formed on the photosensitive metal with a convex lens and the photoelectric saturation current obtained is I. If,the lens is replaced by another similar lens of half the diameter and double the focal-length, then photoelectric -current will be (Assume all lightpassing through lens felling on the photosensitive metal):

An object placed 10 cm in front of a convex lens of focal length 15 cm. The image produced will be

The focal length of a concave lens is 20 cm, if an object is placed at a distance of 50 cm in front of this concave lens, where is the image formed ? What is the nature of the image ?

Describe the nature of image formed when an object is placed at a distance of 30 cm form a convex lens of focal length of 15 cm?