Calculate the focal length of a reading glass of a person, if the distance of distinct vision is 75cm.

Calculate the focal length of a reading glass of a person if his distance of distinct vision is 75 cm.

The magnifying power of a simple microscope is 6. The focal length of its lens in metres will be, if least distance of distinct vision is 25cm

The magnifying power of a simple microscope is 6. The focal length of its lens in metres will be, if least distance of distinct vision is 25cm

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.

What focal length should the reading spectacles have for a person for whom the least distance of distinct vision is 50 cm ?

What focal length should the reading spectacles have for a person for whom the least distance of distinct vision is 50 cm?