Human Eye and Colourful World Test

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Human Eye and Colourful World Test - 49

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Weekly Quiz Competition

Question 1
1 / -0

When objects at different distances are seen by the eye which of the following remain constant?

A
Focal length of eye-lens

B
Object distance from eye-lens

C
The radii of curvature of eye-lens

D
Image distance from eye-lens

Solution

Objects at different distances are seen by the eye by focusing them on the retina of the eye by changing the focal length of the eye lens.
But the image is always formed at the retina and hence image distance from the eye lens remains constant.
Question 2
1 / -0

Very fine particles mainly scatter _______ coloured light.

A
Red

B
Blue

C
Green

D
Yellow

Solution

Very fine particles mainly scatter blue colour light. As the wavelength of blue colour light is lowest as compare to red colour and fine particles and molecules like oxygen and nitrogen being smaller in size scatter effectively the shorter wavelength light.
Question 3
1 / -0

The least distance of distinct vision is ________.

A
25 m

B
340 cm

C
25 cm

D
17 cm

Solution

The least distance up to which we can see the objects clearly without any strain is called least distance of distinct vision. Least distance of distinct vision for a normal human being is 25cm. For young people, the least distance of distant vision will be within 25cm which however it varies with age. For infants, the least distance of distinct vision is about 5 to 8 cm. As the person grows old, their culinary muscles responsible for adjusting the eye lens get weakened. As a result, the power of accommodation reduces and hence the least distance of distinct vision for old people (55years) generally increases. This defect is called Presbyopia.
Question 4
1 / -0

The hypermetropia is a

A
short sighted defect

B
long sighted defect

C
bad vision due to old age

D
none of these

Solution

The hypermetropia is also termed as a long-sighted defect. A person suffering from this defect can see only distant objects clearly but not the nearby objects. This defect can be corrected by using a convex lens.
Question 5
1 / -0

The defect hypermetropia can be corrected by using a ..................

A
Convex lens

B
Concave lens

C
Concave mirror

D
Convex mirror

Solution

The defect hypermetropia can be corrected by using a convex lens of appropriate power.
Hypermetropia is also known as far -sightedness. A person with hypermetropia can see distant objects clearly but cannot see nearby objects distinctly. The near point, for the person, is farther away from the normal near point ($$25 cm$$). Such a person has to keep a reading material much beyond $$25 cm$$ from the eye for comfortable reading. This is because the light rays from a closeby object are focussed at a point behind the retina (b). This defect arises either because (i) the focal length of the eye lens is too long, or (ii) the eyeball has become too small. This defect can be corrected by using a convex lens of appropriate power. Eye-glasses with converging lenses provide the additional focussing power required for forming the image on the retina.
Question 6
1 / -0

Choose the correct alternative which matches second and third column .
Column I
Column II
Column III
I. Thickening of eye lens
A. Focal length increases
i. Ciliary muscles contract
II. Thining of eye lens.
B. Focal length decreases
ii. Ciliary muscles elongate

A
(I)- (B)- (i), (II)-(A)-(ii)

B
(I)-(B)-(ii), (II)-(A)-(i)

C
(I)-(A)-(i), (II)-(B)-(ii)

D
(I)-(A)-(ii), (II)-(B)-(i)

Solution

When the ciliary muscles contract, then the eye lens becomes thick and thus the focus of the eye lens shifts nearer to the lens. Hence the focal length of the eye lens decreases.
On the other hand, when the ciliary muscles elongate, then the eye lens becomes thin and thus the focus of the eye lens shifts away from the lens. Hence the focal length of the eye lens increases.
Question 7
1 / -0

As the thickness of the atmosphere increases the color of scattered light is found in ________ order.

A
Blue, violet, yellow, red

B
Violet, blue, yellow, red

C
Red, yellow, blue, violet

D
Violet, blue, red, yellow

Solution

The short-wavelength blue and violet are scattered by molecules in the air much more than other colors of the spectrum because of which blue and violet light reaches our eyes from all directions.
As the thickness of the atmosphere increase, more molecules are available to scatter the violet and blue light away from our eyes. If the path is long enough, all of the blue and violet light scatters out of our line of sight. The other colors orange, red continues on their way to your eyes.
The sky often appears red because larger particles of dust, pollution, and water vapor in the atmosphere reflect and scatter more of the reds and yellows.
Question 8
1 / -0

At which place in the eye, image is formed of a person is far-sightedness (hypermetropia)?

A
On retina

B
Behind the retina

C
Infront of retina

D
On lens of eye

Solution

Hypermetropia is also known as farsightedness. A person with hypermetropia can see distant objects clearly but cannot see nearby objects distinctly. The near point, for the person, is farther away from the normal near point $$(25\ cm)$$. This is because the light rays from a closeby object are focussed at a point behind the retina
Question 9
1 / -0

Which is true for the far sightedness or hypermetorpia from the following?

A
Eye lens does not become thin as per requirement

B
Distant object cannot be seen clearly

C
Nearby object cannot be seen clearly

D
Defect can be corrected by using concave lens
Question 10
1 / -0

Which coloured light scatters least by fog and smoke?

A
Green

B
Yellow

C
Blue

D
Red

Solution

The color of the scattered light depends on the size of the scattering particles. The molecules of air and other fine particles in the atmosphere have sizes smaller than the wavelength of visible light. Red color light has a maximum wavelength and hence is scattered the least.

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Column I	Column II	Column III
I. Thickening of eye lens	A. Focal length increases	i. Ciliary muscles contract
II. Thining of eye lens.	B. Focal length decreases	ii. Ciliary muscles elongate

Human Eye and Colourful World Test - 49

Result

Human Eye and Colourful World Test - 49

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Rank

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SHARING IS CARING

Question 1

Focal length of eye-lens

Object distance from eye-lens

The radii of curvature of eye-lens

Image distance from eye-lens

Solution

Question 2

Red

Blue

Green

Yellow

Solution

Question 3

25 m

340 cm

25 cm

17 cm

Solution

Question 4

short sighted defect

long sighted defect

bad vision due to old age

none of these

Solution

Question 5

Convex lens

Concave lens

Concave mirror

Convex mirror

Solution

Question 6

(I)- (B)- (i), (II)-(A)-(ii)

(I)-(B)-(ii), (II)-(A)-(i)

(I)-(A)-(i), (II)-(B)-(ii)

(I)-(A)-(ii), (II)-(B)-(i)

Solution

Question 7

Blue, violet, yellow, red

Violet, blue, yellow, red

Red, yellow, blue, violet

Violet, blue, red, yellow

Solution

Question 8

On retina

Behind the retina

Infront of retina

On lens of eye

Solution

Question 9

Eye lens does not become thin as per requirement

Distant object cannot be seen clearly

Nearby object cannot be seen clearly

Defect can be corrected by using concave lens

Question 10

Green

Yellow

Blue

Red

Solution

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