A magnifying glass is made of a combination of a convergent lens of power 20D and divergent lens of power 4D. If the least distance of distinct vision is 25cm. The magnifying power is

A magnifying glass is a combination of a convex lens of focal length 5 cm and a concave lens of power - 5D. If the distance of distinct vision 20 cm, calculate the magnifying power of the magnifying glass.

A convex lens of focal length 10 cm and imag formed by it, is at least distance of distinct vision then the magnifying power is

A magnifying glass is a combination of lenses of powers +20 D and -5 D . Calculate the magnifying power of the microscope, if the distance of distinct vision is 25 cm. Also, calculate the size of an object 3 cm high seen through the magnifying glass.

A convergent lens of power 8 D is combined with a divergent lens of power - 10 D . Calculate focal length of the combination.

The focal length of objective and eyelens of a astonomical telescope are respectively 20 cm and 5 cm. Final image is formed at least distance of distinct vision. The magnifying power will be

A simple microscope consists of a concave lens of power of - 10 D and a convex lens of power + 30 D in contact. If the image formed is at infinity, what is the magnifying power of microscope ? Take distance of distinct vision = 25 cm .

The focal length of objective and eye lens of a astronomical telescope are respectively 2m and 5 cm . Final image is formed at (i) least distance of distinct vision (ii) infinity. The magnifying power in both cases will be