A certain nearsighted person cannot see objects clearly,when they are more than 78 cm from either eye.
The person's near pint is 23 cm.How is this affected,when viewing through the corrective lenses?Assume that the lenses in spectales are 3 cm in front of the eye.

A farsighted person has a near point of 75 cm for one eye and a near point of 100 cm for the other .What pwers should corrective lenses have to allow the person to see an object clearly at a distance of 25cm.

A certain person can see clearly objects at a distnaces btween 20 cm and 250 cm from his eye. What spectacles are required to enable him to see distant objects clearly?

A certain myopic person has a far point of 150 cm. What power of a corrective lens must have to allow him to see distant objects clearly ?

A person with a normal near point (25 cm) using a compound microscope with objective of focal length 8.0 mm and an eyepiece of focal length 2.5cm can bring an object placed at 9.0mm from the objective in sharp focus. What is the separation between the two lenses? Calculate the magnifying power of the microscope.