Question

**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.

Answer #1

I
have 3 questions
1) what power reading glasses are needed for a person whose
near point is 144cm, so that he can read a computer screen at 54cm?
Assume a lens-eye distance of 1.8cm
2) the overall magnification of an astronomical telescope is
desired to be 25x if an object of 84cm focal length is used, what
must be the focal length of the eyepiece?
3) the overall magnification of an astronomical
telescope is desired to be 25x if...

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.

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?

What is the far point of a person whose eyes have a relaxed
power of 52.3 D? Assume the lens-to-retina distance is 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...

A pair of glasses is designed for a person with a far-point
distance of 4 m so that she can read street signs 19.5 m away. (The
far-point distance is the distance from the eye at which you are
just able to properly focus a distant object.)
(a) If the glasses are to be worn 1.0 cm from her eyes, what is
the needed focal length? Answer: -5.02 m
(b) Compare this focal length (find the percent difference) to
the...

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...

QUESTION: A person has a near point of NP = 95 cm and a
far point of FP = 155 cm. The person wishes to obtain a
pair of bifocal eyeglasses to correct these vision problems. The
glasses will sit a distance d = 1.6 cm from the eyes.
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.
P1=________...

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

Suppose that a person's lenses have a refractive power of 2.75 diopters that allow the person to focus on an object that is 25 cm from the eye. The glasses are 2.00 cm in front of the eyes.
a) Is the close point of this person greater than or less than 57.0 cm? What is the distance from the near point when the glasses have a refractive power of 2.53 diopters? Explain b) find the close point of this person.

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