Contact lenses are placed right on the eyeball, so the distance from the eye to

Question

Contact lenses are placed right on the eyeball, so the distance from the eye to an object (or image) is the same as the distance from the lens to that object (or image). A certain person can see distant objects well, but his near point is 50.0 cm from his eyes instead of the usual 25.0 cm .

Part A

Is this person nearsighted or farsighted?

SubmitMy AnswersGive Up

Part B

What type of lens (converging or diverging) is needed to correct his vision?

SubmitMy AnswersGive Up

Part C

If the correcting lenses will be contact lenses, what focal length lens is needed ?

SubmitMy AnswersGive Up

Part D

What is the power corresponding to the focal length found in part (C) in diopters?

SubmitMy AnswersGive Up

Contact lenses are placed right on the eyeball, so the distance from the eye to an object (or image) is the same as the distance from the lens to that object (or image). A certain person can see distant objects well, but his near point is 50.0 cm from his eyes instead of the usual 25.0 cm .

Part A

Is this person nearsighted or farsighted?

Is this person nearsighted or farsighted? This person is nearsighted. This person is farsighted.

SubmitMy AnswersGive Up

Part B

What type of lens (converging or diverging) is needed to correct his vision?

What type of lens (converging or diverging) is needed to correct his vision? A converging lens is needed to correct his vision. A diverging lens is needed to correct his vision.

SubmitMy AnswersGive Up

Part C

If the correcting lenses will be contact lenses, what focal length lens is needed ?

f =   cm  

SubmitMy AnswersGive Up

Part D

What is the power corresponding to the focal length found in part (C) in diopters?

D =   diopters  

SubmitMy AnswersGive Up

Explanation / Answer

here,

A converging or positive lens is required, with
a power such that when an object is placed 25 cm in front of the lens, the lens forms a virtual image.

so the person is farsighted .

Image distance, di = 50 cm
object distance, do = 25 cm

From thinlens formula,
1/f = 1/do + 1/di
1/f = 1/25 + 1/50
f = 16.667 cm
or
f = 0.16667 m

Power of lens, P = 1/f (f should in m)
P = 1/0.16667
P = 6 diopters

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

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