Question

The far point of an eye is 185 cm. A corrective lens is to be used to allow this eye to focus clearly on objects a great distance away. What should be the focal length of this lens?

What is the power of the needed corrective lens in diopters?

Answer #1

1/f = 1/v + 1/u where f is the focal length of the lens, v is the
image distance, and u is the object distance. Because the image is
a virtual one, v is given a negative sign.

1/f = - 1/105

f = 1.05m

b) The power in diopters is the reciprocal of the focal length in
metres; this is 0.952 diopters

2. Correcting vision: quantitative. Corrective lenses work
because the lens bends light such that it, combined with the eye
itself, light forms a clear image on the retina. Another way to
think about this is that the corrective lens (glasses) form an
image of the object at a location where the eye can see clearly
without corrective lenses. For a nearsighted person viewing an
object very far away (object at infinity), the lens corrective lens
creates an image at the...

The distance from the eye lens (i.e. cornea-lens system) to the
retina of a particular eye is 2.02 cm. The power of the eye lens
when it is relaxed is 54.1 D.
(a) Calculate the far point of the eye. (m)
(b) If a corrective lens is to be placed 1.78 cm from the eye,
calculate the power of the corrective lens that will allow the eye
to focus on distant objects. (D)

You
are designing eye glasses got someone whose neR point is 100 cm.
A) neglecting the eye lens distance, what focal length lens
should you prescribe so that an object can clearly be seen when
placed at 25 cm in front of the eye? (Hint =25 cm and q= -100
cm)
B) what is the lens power in diopters?

1) The distance from the lens to the retina is 3.1 cm, what is
the effective focal length of the lens when staring at an object
infinitely far away?
2) An object is moved to 40cm from the eye. What must the focal
length of the eye be to focus the image on the retina?
3) In the near sighted eye, images focus before hitting the
retina. Suppose the focal length of the lens is 1.9 cm, while the
distance...

The uncorrected eye.
For the following questions, assume that the distance between the
eye lens and the retina is 1.70 cm. In other words, since the image
is always formed on the retina, the distance between the lens and
the image is always 1.70 cm. Also note that, as is seen in the ray
diagram, since the eye lens is converging and the image is on the
opposite side of the lens compared to the object, the image is
always...

The uncorrected far point of Charlotte's eye is 2.1 m. What
refractive power contact lens enables her to clearly distinguish
objects at large distances? Assume that the distance from the
cornea-lens system to the retina is 2.0 cm and the normal near
point is 28 cm.

The lens-to-retina distance of a woman is 1.92 cm, and the
relaxed power of her eye is 54.0 D.
(a) What is her far point?
m
(b) What eyeglass power will allow her to see distant objects
clearly, if her glasses are 1.80 cm from her eyes?
D

The near point of a patient's eye is 54.2 cm.
(a) What should be the refractive power ℛ of a
corrective lens prescribed to enable the patient to clearly see an
object at 23.0 cm?
ℛ = dpt
(b) When using the new corrective glasses, the patient can see an
object clearly at 26.8 cm but not at 23.0 cm. By how many diopters
did the lens grinder miss the prescription?
? = dpt

A patient's far point is 135 cm and her near point is 15.0
cm.
In what follows, we assume that we can model the eye as a simple
camera, with a single thin lens forming a real image upon the
retina. We also assume that the patient's eyes are identical, with
each retina lying 1.95 cm from the eye's "thin lens."
(a)
What is the power, P, of the eye when focused upon the
far point? (Enter your answer in...

(a) Where is the near point of an eye for which a contact lens
with a power of +2.95 diopters is prescribed?
cm (in front of the eye)
(b) Where is the far point of an eye for which a contact lens with
a power of -1.35 diopters is prescribed for distant vision?
cm (in front of the eye)

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