A person has a near point of NP = 65 cm and a far point of FP = 150 cm. The pers

Question

A person has a near point of NP = 65 cm and a far point of FP = 150 cm. The person wishes to obtain a pair of eyeglasses to correct these vision problems. The glasses will sit a distance d = 25 cm from the eyes. Part (a) Write a formula for the power, P_1, 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, P_1, of the upper portion of the bifocals in units of diopters. Part (c) Write a formula for the power, P_2 of the lower portion of the bifocals, in terms of given quantities, so that the person can clearly see objects that are located a distance N from his eyes. Part (d) Calculate the power, P_2, of the lower portion of the bifocals in units of diopters. Use N = 25 cm, which is for normal human vision.

Explanation / Answer

a)

P1 = -1/(Fp -d)

(b)

P1 = -1/(1.5-0.025) = -0.68 diopters

(c)

object distance = N

image distance = -(q-d) = -(65 - 2.5) = -62.5 cm

p2 = 1/p + 1/q

1/p2 = 1/N - 1/(Np-d)

(d)

1/p2 = 1/0.25 - 1/(0.65-0.025)

p2 = 0.42 diopters

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.