Myopia and Its Cure

Q. A myopic person has been using spectacles of power –1.0 dioptre for distant vision. During old age he also needs to use separatereading glass of power + 2.0 dioptres. Explain what may have happened.

Q. The focal length of convex lens is 2.5 cm. Its magnifying power for minimum distance of distinct vision will be

Q.

Calculate the focal length of a reading glass of a person if this distance of distinct vision is 75 cm.

1. 75.2 cm

2. 25.6 cm

3. 100.4 cm

4. 37.5 cm

Q. A person can see clearly only up to a distance of 25 cm. He wants to read a book placed at a distance of 50 cm. What kind of lens does he require for his spectacles and what must be its power ?

1. Concave, -2.0 D
2. Convex, +2.0 D
3. Concave, -1.0 D
4. Convex, +1.5 D

Q. A man can see clearly up to 3 metres. Prescribe a lens for his spectacles so that he can see clearly up to 12 metres

1. 3D
2. -4 D
3. $-\frac{3}{4}D$
4. $-\frac{1}{4}D$

Q.

The defect caused by the shortening of the eyeball from front and back.

Q.

A person with myopic eyes is not able to see objects beyond $3m$. Determine the nature, focal length, and power of the correcting lens.

Q.

A person looking at a person wearing a shirt with a pattern comprising vertical and horizontal lines is able to see the vertical lines more distinctly than the horizontal ones. What is this defect due to? How is such a defect of vision corrected?

Q. Does short-sightedness (myopia) or long-sightedness (hyper -metropia) imply necessarily that the eye has partially lost its abilityof accommodation? If not, what might cause these defects of vision?

Q.

For the myopic eye, the defect is cured by

[CPMT 1990; KCET (Engg.) 2000]

1. Convex lens

2. Cylindrical lens

3. Concave lens

4. Toric lens

Q. A telescope consists of two convex lenses of focal length $16\text{cm}$ and $2\text{cm}$. If the object subtends an angle of ${0.5}^{\circ }$ on the eye, what will be the angle subtended by the image on the eyepiece in relaxed eye? (In degree)

Q.

A man who cannot see clearly beyond 5 m wants to see stars clearly. He should use a lens of focal length

[MP PET/PMT 1988; Pb. PET 2003]

1. - 5 m

2. Very large

3. - 100 m

4. + 5 m

Q. The far point of a myopic person is 150cm in front of the eye. Calculate the focal length of the lens requires to enable him to see distant objects clearly.

Q. 43 the focal length of convex lens is 2.5 cm.Its magnifying power for minimum distance of distinct vision will be

Q. A myopic person can not see objects lying beyond $2\text{m}$. The focal length and power of the lens required to remove this defect will be

1. $1\text{m}\&0.5\text{D}$
2. $-2\text{m}\&-0.5\text{D}$
3. $0.5\text{m}\&0.5\text{D}$
4. $-0.5\text{m}\&0.5\text{D}$

Q. 11.A telescope has an objective of focal length 50cm and eye piece of focal length 5cm .the least distance of distinct vision is 25cm .the telescope is focussed for distinct vision on a scale 200cm away from the objective . calculate the separation between objective and eye piece lens and magnification produced.

Q.

A person looking at a person wearing a shirt with a pattern comprising vertical and horizontal lines is able to see the vertical lines more distinctly than the horizontal ones. What is this defect due to? How is such a defect of vision corrected?

Q.

Image is formed for the short sighted person at

[AFMC 1988]

1. Retina

2. Before retina

3. Behind the retina

4. Image is not formed at

Q. What Benjamin Franklin invented?

1. Bifocal spectacles
2. Radio
3. Barometer
4. Hygrometer

Q. Mark the correct option.

1. If the far point moves farther, the power of the divergent lens should be reduced.
2. If the near point moves farther, the power of the convergent lens should be reduced.
3. If the far point is at $1\text{m}$ from the eye, a converging lens should be used.
4. If the near point is at $1\text{m}$ from the eye, a diverging lens should be used.

Q. Answer the following questions:

Q. The far point of a myopic persons is $00cm$ in-front of him. What is the power of the lens to correct the problem of his eye?

1. $-1.0D$
2. $+1.0D$
3. $-1.25D$
4. $+1.25D$

Q. A convex lens of focal length f produces a real image n times the size of an object, then the distance of the object from the lens is :

1. $(n+1)f$
2. $\left(\frac{n+1}{n}\right)f$
3. $(n-1)f$
4. $\left(\frac{n-1}{n}\right)f$

Q. An object is to be seen through a simple microscope of focal length $10\text{cm}$. Where should the object be placed so as to produce maximum angular magnification ? The least distance for clear vision is $30\text{cm}$.

1. $8.5\text{cm}$
2. $7.5\text{cm}$
3. $6.5\text{cm}$
4. $9.5\text{cm}$

Q. A man can see the objects up to a distance of one metre from his eyes. To see objects at infinity, he needs a lens of focal length

1. 0.5 D
2. +1.0 D
3. +2.0 D
4. –1.0 D

Q. A person can see clearly objects only when they lie between $50cm$ and $400cm$ from his eyes. In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use, will be?

1. Convex, $+2.25$ dioptre
2. Concave, $-0.25$ dioptre
3. Concave, $-0.2$ dioptre
4. Convex, $+0.15$ dioptre

Q. A man can see the objects up to a distance of one metre from his eyes. For correcting his eyesight so that he can see an object at infinity, he requires a lens whose power is

1. +1.0 D
2. +2.0 D
3. –1.0 D
4. +0.5 D

Q. Boojho while waving his hand very fast in front of his eyes, observes that his fingers appear blurred. What could be the reason for it?

Q. A myopic person can not see objects lying beyond $2\text{m}$. The focal length and power of the lens required to remove this defect will be

1. $1\text{m}\&0.5\text{D}$
2. $-2\text{m}\&-0.5\text{D}$
3. $0.5\text{m}\&0.5\text{D}$
4. $-0.5\text{m}\&0.5\text{D}$

Q. A myopic person has been using spectacles of power $-1.0D$ for distant vision. During old age, he also needs to use a separate reading glass of power $+2.0D$. Explain what may have happened.