Crystalline Lens

Q.

Which type of lens the human eye has?

1. Convex lens

2. Concave lens

3. Plano-convex lens

4. Plano-concave lens

Q. What is the function of the lens in the human eye ?

Q.

What is the eye lens composed of?

1. granuels

2. fibrous, jelly like material

3. fibrous, thin material

4. none of these

Q.

(a) Which parts of the eye cause rays of light to converge on the retina ?
(b) Which part causes the greatest convergence ?
(c) Which part brings the image into sharp focus on the retina ? How does it do this ?

Q.

What is the principal function of the eye lens?

Q.

What is the principal function of the eye-lens ?

Q. Ciliary muscle to see nearby objects and to see distant objects.

1. contracts
2. expands
3. weakens
4. flattens

Q. If we keep the objects close to the eye, the ciliary muscles ________.

1. expand
2. contract
3. remain same
4. reflect all the light

Q. If we keep the objects close to the eye, the ciliary muscles ________.

1. expand
2. contract
3. remain same
4. reflect all the light

Q.

Write A Composition On Eyes

Q.

The image can not be seen distinctly because eye lens become milky and cloudy. This condition is known as

Q. The eyes of a person are focused (i) on a nearby object, and (ii) on a distant object, turn by turn. In which case :
(a) the focal length of eye-lens will be the maximum ?
(b) the converging power of eye-lens will be the maximum ?

Q.

If the light source in front of an eye becomes suddenly bright

1. focus of lens will change

2. retinal blood supply will be cut off

3. vitreous humour will become fluid

4. pupil will contract

Q.

Why the crystalline lens of people at old age become milky?

Q. Which part of human eye changes its shape??

Q. Why does the eye-lens not have to do all the work of converging incoming light rays ?

Q.

How can you compare various parts of eye with photographic camera?

Q. A child is looking at a distant object. The ciliary muscles of his eye will

1. contract
2. expand
3. remain the same

Q.

The crystalline lens of human eye is of what shape?

1. concavo- convex

2. bi concave lens

3. bi convex lens

4. parabolic

Q. What shape are your eye-lenses :
(a) when you look at your hand ?
(b) when you look at a distant tree ?

Q. The human eye is comprised of a ________ lens.

1. multifocal
2. concave
3. bifocal
4. convex

Q. what is the labelled diagram of eye

Q. What is the role of the ciliary muscles?

Q. Solve the following crossword with the help of the given clues:
Across
(1) A microscope consisting two convex lenses
(3) The jelly-like substances that fills the area of the eyeball between the retina and the lens.
(5) A lens mounted in a frame used to make an object appear layer than it really is
(7) The organ of the body with which humans are able to see
(9) The clear, watery fluid that fills the chamber of the eye between the cornea and the lens.
(11) An optical instrument used to view distant objects. It makes far away objects appear larger when viewed through it.
(12) Defect of human eye, by virtue of which a person can see clearly the distant objects but we the nearby objects.
Down
(1) The front transparent part of the eye that is bulged outwards. Light from objects enter the eye through it.
(2) An optical device consisting of a conve lens of small focal length that is used to make things.
(4) An apparatus for taking photographs.
(6) The flat-coloured membrane in the lens that contacts the size of the pupil
(8) The opening in the centre of the iris through wheels light enters the eye.
(10) The defect of human eye due to which a person is able to near objects at close range better than distant objects.

Q. Which of the following are true for a human eye.

1. The image is erect
2. The image is inverted
3. The lens of eye is convex
4. (b) and (c) above

Q. Refraction of light in the eye occurs at :
(a) the lens only (b) the cornea only (c) both the cornea and the lens (d) the pupil

Q.

The human eye lens is crystalline and biconvex in nature?

1. False

2. True

Q. Fill in the blanks
The maximum focal length of the eye lens is about _________.

Q. What kind of lens is present in the human eye ?

Q. Focal length of human eye lens is about _____________.

1. 2.5 m
2. 2.5 cm
3. 2.5 mm
4. 25 cm