The Range of Sight

Q. The diameter of the eye-ball of a normal eye is about 2.5 cm. The power of the eye lens varies from

1. 2 D to 10 D
2. 40 D to 32 D
3. 9 D to 8 D
4. 44 D to 40 D

Q. Two similar plano-convex lenses are combined together in three different ways as shown in the figure below. The ratio of the focal lengths in the three cases will be

1. $2:2:1$
2. $1:1:1$
3. $1:2:2$
4. $2:1:1$

Q.

Image is formed for the short sighted person

1. at retina
2. before retina
3. behind the retina

Q.

Image is formed for the short sighted person

1. at retina
2. before retina
3. behind the retina

Q. For a normal eye, the far point is at infinity and the near point of distinct vision is about $25cm$ in front of the eye. The cornea of the eye provides a converging power of about $40$ dioptres, and the least converging power of the eye - lens behind the cornea is about $20$ dioptres. From this rough data estimate the range of accommodation (i.e., the range of converging power of the eye-lens) of a normal eye.

1. $10$ to $14D$
2. $20$ to $24D$
3. $28$ to $32D$
4. $14$ to $18D$

Q. Match the following for the eye lens:
1. Thicker I. Higher Focal length
2. Thinner II. Lower Focal Length

1. 1-I, 2-II
2. 1-II, 2-I

Q.

Image formed on the retina is

1. Real and inverted

2. Virtual and erect

3. Real and erect

4. Virtual and inverted

Q.

A person cant see the object beyond $25cm$ , the power of lens to correct the vision will be

1. $-4D$

2. $-2D$

3. $-1D$

4. $2D$

Q. Match the following for the eye lens:
1. Thicker I. Higher Focal length
2. Thinner II. Lower Focal Length

1. 1-II, 2-I
2. 1-I, 2-II

Q. The diameter of the eye-ball of a normal eye is about 2.5 cm. The power of the eye lens varies from

1. 2 D to 10 D
2. 40 D to 32 D
3. 9 D to 8 D
4. 44 D to 40 D

Q. If the focal length of the eye lens in Ramsden's eyepiece is $f$, then the focal length of the field lens and separation between the field lens and cross wires are respectively :

1. $3f$ and $f$
2. $f$ and $f/4$
3. $3f$ and $2f$
4. $2f$ and $3f$

Q.

Figure 2.20 (a)–(d) respectively correspond to

1. the short-sighted eye, the correction of long-sight, the long-sighted eye and the correction of short-sight

2. the short-sighted eye, the correction of short-sight, the long-sighted eye and the correction of long-sight

3. the long-sighted eye, correction of short-sight, the short-sighted eye and the correction of long-sight

4. none of these

Q. For a normal eye, The cornea of eye provides a converging power of $40D$ and the least converging power of the eye lens behind the cornea is $20D$. Using this information, the distance between the retina and the cornea eye lens can be estimated to be.

1. $1.5cm$
2. $5cm$
3. $2.5cm$
4. $1.67cm$

Q. Assertion :The focal length of the objective in a telescope is larger than that of eyepiece. Reason: Magnifying power of telescope increases when the aperture is large

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. When we see an object, the image formed on the retina is
(a) real
(b) virtual
(c) erect
(d) inverted

Q. A lens acts as a converging lens in air and diverging lens in water. The refractive index of the lens is

1. =1
2. <1.33
3. <1
4. >1.33

Q. Image is formed for the short sighted person at

1. Retina
2. Behind the retina
3. Before retina
4. Image is not formed at all

Q.

For a normal eye, the least distance of distinct vision is

[CPMT 1984]

1. 0.25 m

2. 0.50 m

3. 25 m

4. Infinite

Q.

For a normal eye, the least distance of distinct vision is

[CPMT 1984]

1. 0.25 m

2. 25 m

3. 0.50 m

4. Infinite

Q. explain how we perceive objects as they are?

Q. a person uses spectacles of power -0.5D for distinct vision . How far is the far point of the person?

Q.

Image formed on the retina is

1. Real and inverted

2. Virtual and erect

3. Real and erect

4. Virtual and inverted

Q. The focal length of a thin convex lens is _____ than that of a thick convex lens.

1. more
2. less
3. same as
4. can't say

Q.

Image formed on the retina is

1. Real and inverted

2. Virtual and erect

3. Real and erect

4. Virtual and inverted

Q.

When the ciliary muscles are relaxed, then the focal length of the eye lens ___.

1. first increases then decreases

2. remains constant

3. increases

4. decreases

Q. The focal length of a normal and relaxed eye lens is about -

1. $2\text{cm}$
2. $1\text{cm}$
3. $1\text{mm}$
4. $2\text{mm}$