Eye Mechanism

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

Q.

How does the eye change in order to focus on near or distant objects ?
(a) The lens moves in or out (b) The retina moves in or out
(c) The lens becomes thicker or thinner (d) The pupil gets larger or smaller

Q.

While taking the reading of meter, what should be the position of eye

Q.

Which of the following equipment works on similar principle as human eye?

1. Telescope

2. Camera

3. Gun

4. Microscope

Q. (a) Explain the functions of the following parts of the eye :
(a) cornea (b) iris (c) pupil (d) ciliary muscles (e) eye-lens
(f) retina (g) optic nerve
(b) If you walk from a dark room into sunlight and back again into dark room, how would your pupils after in size ? What makes this happen ?
(c) Explain why, we cannot see our seats first when we enter a darkened cinema hall from bright light but gradually they become visible.

Q. (a) How does the convex eye-lens differ from the ordinary convex lens made of glass ?
(b) List, in order, the parts of the eye through which light passes to reach the retina.

Q.

Cornea is a transparent spherical structure which

1. reflects light

2. scatters light

3. refracts light

4. none of these

Q. Out of the two types of photoreceptors of a human eye, the measure intensity of light whereas the sense colours.

1. cones
2. rods
3. optic nerves
4. ciliary muscles

Q.

The human eye forms an image of an object at its

1. cornea

2. iris

3. pupil

4. retina

Q.

The image formed on the retina of a human eye is

1. temporary

2. permanent

3. blurred

4. none of these

Q. What is the nature of the image of an object formed on the retina of the human eye?

1. Virtual and Erect
2. Real and Erect
3. Real and Inverted
4. Virtual and Inverted

Q.

Amount of light entering the eye is controlled by:

1. Iris

2. Cornea

3. Pupil

4. Crystalline lens

Q.

How does pupil work? What is persistence of vision and power of accommodation? [5 MARKS]

Q. The centre point of a biconvex lens which lies on the principal axis is called the .

1. focus
2. optic centre
3. centre of curvature

Q.

Automatic focusing is done by human eye by

1. Changing the convexity of the eye surface

2. Changing the thickness of the fluid in the eye

3. To and fro motion of the eye

4. To and fro motion of the retina

Q. What is the far and near point of human eye with normal vision.

Q. A human eye can form sharp images of different objects lying at different distances by changing the focal length of the eye lens on the retina. This is done to achieve

1. hypermetropia
2. myopia
3. accommodation
4. persistence of vision

Q.

The pupil appears black because no light is reflected from it.

1. True
2. False

Q.

Question 25
Explain the structure and functioning of human eye. How are we able to see nearby as well as distant objects?

Q. Convex lens is also known as ______ lens.​

1. converging
2. diverging
3. radial
4. axial

Q. At death pupil _____________.

1. Becomes narrow
2. Becomes wide
3. Shows no reaction to light
4. Both B and C

Q. More than One Answer Type
एक से अधिक उत्तर प्रकार के प्रश्न

A concave lens and a convex lens of focal length 25 cm and 20 cm respectively are placed in close contact. The combination of lenses

फोकस दूरी 25 cm तथा 20 cm के क्रमशः एक अवतल लेन्स तथा एक उत्तल लेन्स को निकट सम्पर्क में रखा जाता है। तब

1. Has focal length 100 cm
   
   लेन्सों के संयोजन की फोकस दूरी 100 cm है
2. Has power 1 D
   
   लेन्सों के संयोजन की क्षमता 1 D है
3. Will be behave as converging lens
   
   लेन्सों का संयोजन अभिसारी लेन्स के समान व्यवहार करेगा
4. Will be behave as diverging lens
   
   लेन्सों का संयोजन अपसारी लेन्स के समान व्यवहार करेगा

Q. Convex lens is also known as ______ lens.

1. converging
2. diverging
3. radial
4. axial

Q. The far-point of a normal healthy eye is located at:

1. $25\text{cm}$
2. $400\text{cm}$
3. $50\text{cm}$
4. $\infty$

Q. How many times does refraction take place in the given figure?

Q. What are the properties of the images formed on the retina?

1. Real
2. Virtual
3. Diminished
4. Highly enlarged
5. Inverted
6. Colourful
7. Erect
8. Focussed
9. Black and white

Q. Answer the following briefly:
What is meant by 'Power of accommodation' of the eye? Name the part of the eye responsible for the same.