Question
You're a practicing optometrist. You receive a prescription tomanufacture a pair of glasses with a power of -0.5 D. What can youconclude about the person who will wear these glasses?a. Their far point has drifted off to infinity.b. They are extremely far-sighted.c. Their near point has drifted to become longer than 25 cm.d. They are extremely near-sighted.Which of the following best describes how the eye creates aclear image on the retina?a. The diameter of the eye flexes.b. The pupil chang
You're a practicing optometrist. You receive a prescription to manufacture a pair of glasses with a power of -0.5 D. What can you conclude about the person who will wear these glasses? a. Their far point has drifted off to infinity. b. They are extremely far-sighted. c. Their near point has drifted to become longer than 25 cm. d. They are extremely near-sighted. Which of the following best describes how the eye creates a clear image on the retina? a. The diameter of the eye flexes. b. The pupil changes its diameter. c. The lens changes shape. d. There are slight changes in the index of refraction of the aqueous humour in the eye.
Answers
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 45.0 cm from his eyes instead of the usual 25.0 cm. (a) Is this person nearsighted or farsighted? (b) What type of lens (converging or diverging) is needed to correct his vision? (c) If the correcting lenses will be contact lenses, what focal length lens is needed and what is its power in diopters?
All right. So Ah, in this case, part for parts. And we should figure out if it is Ah, far side of this person is far sighted or near sighted and on DH. So the near point is greater than 25 centimeters. Ready Importance. 45 centimeters on DSO that gives us on. And so that means the image is formed behind the retina. And when that happens, you have farsighted vision. Finish formed in front of them to written up. In other words, their point is less than 25 centimeters. You know, you'd be near sight. Okay, So a virtual image is forming at the near point in this case. And so from the text, we know that to correct for farsightedness we have to use conversion lenses which can produce the virtual of image on the other side. Damage on the other side off uh, the lens, which is the cornea on DSO for focal in't. We used formula for focal length, just won over Africa. Lt's one over object distance plus one over image distance. And so that's one of her. The 25 centimetres minus one over 45 centimeters. Because, remember, image is forming on the other side of the lens as the object. And so this means that the focal length is UH plus 56.2 centimetres and notice that it's positive. So it's a converging lens and some power will be won over focal ink in meters. So that would be one of her 10.562 meters. And that gives us plus 1.78 Diop tres and that's it.
Are diverging legs is needed to correct. Yeah, his nearsighted nets, Because integrated produce image of the sprint object. Mhm. And his Oh, uncorrected for points. Mhm. Oh, do you think converting lens is needed to correct? Yeah, his far sightedness, because it had been a pretty was an image mhm at his New York point of an object that is loser than his uncorrected near point. Yeah, and I'll see you point. Yeah, for mhm far point. A reflecting power deflecting power of finance will be burned upon us. So it is to be too doctor minus sorry, minus one to damped. And for near point. Mhm. Yeah. So it is to me. Let's do them. Yeah, they're so thanks for watching it.
Solving party of this problem since focal length of the lens age 55 cm as the focal lens of the lens is positive as F. Is equal to positive year. So given lenses are converging in nature, so it is converging in nature. So this is the answer for party. Now I will go to solve part B. So in part we I can like fire site version person, we are the convincing lambs. So this is the answer for part B solving party of this problem. So here in this, But I can write the formula of one by D. I. Is equal to one by f minus one by denote the not each object distance, the distance which is equal to one by 55 minus one by 35 1 simplification, I get the value of the U. S. Just look at it carefully -19-5 x 20. On further simplification, I finally get the value of the I -96.3 cm as our answer.
Are diverging lens is needed to courage. Mhm near sightedness. Mhm. Yeah, because get to Bill. Produce an image. Mm hmm. Of our distinct object heritage. Uncorrected four point chicken part are converting. Length is needed to correct far sightedness because into build produce enemies at his new year point of an object of an of object That is closer. Yeah. Then it's uncorrected near point. Oh, see you. Point. Uh huh. For distinct object Objective strength is infinity Image position is 500 minus two 4. 98 centimeter is given, so, for collect, you will get mhm. You can take it right in meter. No. So this is the reflecting power of the length, which is minus point to diabetes. Yeah, for close object object distance is 25 minus two centimeter or while 2 to 3 m and a major position 15 minutes to that is point for it. We did so Uh huh. Reflecting power of the islands. Yeah. Yeah. So it has to be right. Mhm. Uh huh. Snapped. They're just Thanks for watching it