A full length image of a distant tall building can definitely be seen by using

A sharp image of a distant object is obtained on a screen by using a convex lens. In order to determine the focal length of the lens, you need to measure the distance between the :

A student has obtained a point image of a distant object using a convex lens. To find the focal length of the convex lens, he should measure the distance between the :

An astronomical telescope uses two lenses of powers 10 dioptre and I dioptre. If the final image of a distant object is formed at infinity, calculate the length of the telescope.

An astronomical telescope uses two lenses of powers 10 dioptre and 1 dioptre. If the final image of a distant object is formed at infinity, calculate the length of the telescope.