An image formed on a screen is three times the size of the. Object. The object and screen are 80 cm apart when the image is sharply focused.

(a) State which type of lens is used.

(b) Calculate focal length of the lens.

A camera fitted with a lens of focal length 50 mm is being used to photograph a flower that is 5 cm in diameter. The flower is placed 20 cm in front of the camera lens.

(a) At what distance from the film should the lens be adjusted to obtain a sharp image of the flower?

(b) What would be the diameter of the image of the flower on the film?

(c) What is the nature of camera lens?

An object is 2m from a lens which forms an erect image half (exactly) the size of the object. Determine the focal length of the lens. What type of lens is this?

The lens A has a focal length of 25 cm whereas another lens B has a focal length of 60 cm. Giving reason state, which lens has more power : A or B.

Which causes more bending (or more refraction) of light rays passing through it : a convex lens of long focal length or a convex lens of short focal length ?