A person has a near point of NP = 85 cm and a far point of FP = 210 cm. The person wishes to obtain a pair of bifocal eyeglasses to correct these vision problems. The glasses will sit a distance d = 2.1 cm from the eyes.
Part (a) Write a formula for the power, P1, of the upper portion of the bifocals, in terms of the given quantities, that will enable the person to see distant objects clearly.
Part (b) Calculate the power, P1, of the upper portion of the bifocals in units of diopters.
Part (c) Write a formula for the power, P2, of the lower portion of the bifocals, in terms of given quantities, so that the person canclearly see objects that are located a distance N from his eyes.
Part (d) Calculate the power, P2, of the lower portion of the bifocals in units of diopters. Use N = 25 cm, which is for normal human vision.