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

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 ?

An object placed at 20 cm from a lens, forms an image on a screen placed 60 cm on the other side of the lens. What is the focal length and type of the lens ?

A lens ( focal length 50 cm ) forms the image of a distant object which subtends an angle of 2 milliradian at the lens. What is the size of the image ?

A convex lens of focal length 30 cm produces 5 times magnified real image of an object. What is the object distance?

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?

A candle placed 25 cm from a lens, forms an image on a screen placed 75 cm on the other end of the lens. The focal length and type of the lens should be

A concave lens has focal length of 20 cm . At what distance from the lens a 5 cm tall object be placed so that it forms an image at 15 cm from the lens? Also, calculate the size of the image formed.

An object is placed at a distance of 30 cm from a concave lens of focal length 15 cm . Find the nature and position of the image.