Question

A farsighted eye is corrected by placing a converging lens in front of the eye. The...

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 hyperopia? Assume that the distance from the eye to the lens is negligible.

Science   Physics   
0 0
Add a commentTranscribed image text
Next >

Homework Answers

Answer #1

For a normal eye near point is considered to be 25 cm . For a hyperopia eye image of object placed at near point will be formed behind retina as shown in figure , hence for a hyperopia eye near point shifted away from eye and it will be greater than 25 cm. To correct this defect converging lens is used as shown in figure. Focal length of converging lens is determined using the lens equation

(1/v) - (1/u) = ( 1/f ) ....................(1)

v = lens-to-image distance = -49.5 cm ( Cartesian sign convention is followed )

u = lens-to-object distance = 25 cm

f is focal length of lens

we get , (1/f) = -(1/49.5) + (1/25) = 0.0198 cm-1 or f = 50.51 cm

power of lens = 1/0.505 = +1.98 D

0 0
Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Log In

Sign Up

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
The uncorrected eye. For the following questions, assume that the distance between the eye lens and...
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...
A person is farsighted and has near point of 50 cm. Retina is at a distance...
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...
A) An object is placed 26 cm in front of a converging lens of focal length...
A) An object is placed 26 cm in front of a converging lens of focal length 5 cm. Another converging lens of focal length 10 cm is placed 20 cm behind the first lens. 1) Find the position of the final image with respect to the second lens.  ____cm 2) Find the magnification of the final image. _____ B) A diverging lens of focal length −12cm projects the image of an object onto a wall. What is the object distance if...
(a) Where is the near point of an eye for which a contact lens with a...
(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)
A converging lens and a diverging lens, separated by a distance of 30.0 cm, are used...
A converging lens and a diverging lens, separated by a distance of 30.0 cm, are used in combination. The converging lens has a focal length of 15.2 cm. The diverging lens is of unknown focal length. An object is placed 19.3 cm in front of the converging lens; the final image is virtual and is formed 12.0 cm in front of the diverging lens. What is the focal length of the diverging lens?
An object is placed in front of a converging lens with a radius of curvature of...
An object is placed in front of a converging lens with a radius of curvature of 4.88 cm. An image is formed 12.9 cm from the object. (a) Calculate how far is the lens from the object if the image is virtual. (b) How far is image from the lens?
a. A real object 4.0 cm high stands 30.0 cm in front of a converging lens...
a. A real object 4.0 cm high stands 30.0 cm in front of a converging lens of focal length 23 cm. Find the image distance, the image height, if the image is real or virtual (explain in detail) and if the image is erect or inverted (explain in detail). b. The real object is now placed 13.0 cm in front of the converging lens. Again find the paramaters listed above. Graphically show the optic configuration for this second object placement.
2. Correcting vision: quantitative. Corrective lenses work because the lens bends light such that it, combined...
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...
Contact lenses are placed right on the eyeball, so the distance from the eye to an...
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....
1) The distance from the lens to the retina is 3.1 cm, what is the effective...
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...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT