Question

What power of spectacle lens is needed to allow a farsighted person, whose near point is 2.50 m, to see an object clearly that is 20.0 cm away? Assume the spectacle (corrective) lens is held 2 cm away from the eye by eyeglass frames.

Answer #1

*When the object is
away from the eyes, the lens should produce image at near point
. Since lens is away from the eyes at
, the image will be at
away from the eyes. Therefore, image distance
and object distance is
.*

*The power
of lens is given by:*

*Therefore, lens power must be 5.1523 Dioptre for given
situation.*

A) A farsighted person wears a spectacle whose power is
2.50 D to see an object clearly that is 25.0 cm away? What is the
near point of this person. Assume the spectacle (corrective) lens
is held 1.50 cm away from the eye by eyeglass frames. Answer:
m
B)
Two lens with f = 10.0cm are 20.0cm apart. An object is placed
30.0cm from the left lens. How far from the right lens will an
image be formed?
Answer:...

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...

7. Reading glasses of what power are needed for
a person whose near point is 80.0 cm, so that she can read clearly
the print of a book located at 26.0 cm? Assume a lens-eye distance
of 2.00 cm.

A farsighted eye is corrected by placing a converging lens in
front of the eye. The lens will create a virtual image that is
located at the near point (the closest an object can be and still
be in focus) of the viewer when the object is held at a comfortable
distance, usually taken to be 25.0 cm.25.0 cm. If a person has a
near point of 49.5 cm,49.5 cm, what power reading glasses should be
prescribed to treat this...

1. What is the optical power of the eye when viewing an object
from a distance of 23.5 cm?
2.What is the far point for a person whose eyes have a relaxed
power of 50.25 D?
3. What power lens is required to correct a myopic (nearsighted)
eye with a far point of 6.50 m? Neglect the distance between the
corrective lens and the eye.
4. What power lens is required to correct a hyperopic
(farsighted) eye with a...

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?

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 person is farsighted and has near point of 50 cm. Retina is at
a distance L = 1.7 cm. When wearing contact lenses and reading a
book 30 cm in front of the eye, what is the object distance for the
lenses? What is the desired image distance? Is the magnitude of the
image distance a minimum, maximum, or the only acceptable image
distance? Find the focal length and refractive power of the contact
lens that will fix this...

The contacts worn by a farsighted person allow her to see
objects clearly that are as close as 25.0 cm, even though her
uncorrected near point is 81.0 cm from her eyes. When she is
looking at a poster, the contacts form an image of the poster at a
distance of 237 cm from her eyes. (a) How far away is the poster
actually located? (b) If the poster is 0.400 m tall, how tall is
the image formed by...

The contacts worn by a farsighted person allow her to see
objects clearly that are as close as 25.0 cm, even though her
uncorrected near point is 91.0 cm from her eyes. When she is
looking at a poster, the contacts form an image of the poster at a
distance of 208 cm from her eyes. (a) How far away
is the poster actually located? (b) If the poster
is 0.330 m tall, how tall is the image formed by...

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