A convex lens of focal length 20 cm is placed at a distance of 30 cm from a screen. Where should an object be placed so as to form its real image on the screen?

A convex lens of focal length 15 cm is placed in front of a convex mirror co-axially 5 cm from the mirror. The image of an object placed at a distance 20 cm from the lens found to have been formed over the object. Estimate the radius of curvature of the mirror.

Focal length of a convex lens is 15cm. Where should an object be placed so that real and three times larger image is formed?

A concave lens of focal length 15cm forms an image 10cm from the lens. How far is the object placed from the lens? Draw the ray diagram.

When an object is placed at a distance of 60 cm from a convex mirror, the magnification produced is 1/2. Where should the object be placed to obtain a magnification of 1/3?

An object is placed at a distance of 50 cm from a concave lens of focal length 20 cm. Find the nature and position of the image.

A convex lens forms a real and inverted image of a needle at a distance of 50 cm. from it . Where is the niddle placed in front of convex lens if the image is equal to the size of the object? Also , find the power of the lens.

a concave lens of focal length 20cm is placed in contact with a convex lens of focal length 40cm. Find the power of the combination.

An object of size 7.0cm is placed at 27cm in front of a concave mirror of focal length 18cm. At what distance from the mirror should a screen be placed,so that a sharp focussed image can be obtained? Find the size and the nature of the image.