Human Eye and Colourful World Test

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Human Eye and Colourful World Test - 18

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Weekly Quiz Competition

Question 1
1 / -0

A person can see clearly object only when they lie between 50 cm and 400 cm 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 :

A
Convex, + 0.15 D

B
Convex, +2.25 D

C
Concave, -0.25 D

D
Convex, + 0.2 D

Solution

Image distance, $$v=-4\ m$$

We know that: $$\dfrac{1}{-4}-\dfrac{1}{\infty}=\dfrac{1}{d}$$

$$\Rightarrow P=\dfrac{1}{d}=-0.25 $$ D

It is a concave lens.
Question 2
1 / -0

A far sighted person has his near point 50 cm. Find the power of lens he should use to see at 25 cm clearly.

A
+1 D

B
+2 D

C
-2 D

D
-1 D

Solution

In order for a person to see the object at 25cm clearly, the lens should make an image of the object at 25cm distance at a distance of 50 cm.
Hence, $$u=-25cm=-0.25m$$
$$v=-50cm=-0.5m$$
Thus, Power $$=\dfrac{1}{f}=\dfrac{1}{v}-\dfrac{1}{u}=-2D+4D=+2D$$
Question 3
1 / -0

For a person near point of vision is $$100\ cm$$. Then the power of lens he must wear so as to have normal vision, should be:

A
$$+1\ D$$

B
$$-1\ D$$

C
$$+3\ D$$

D
$$-3\ D$$

Solution

For normal vision, $$u =-25$$ cm
Given : $$v = -100$$ cm
Using lens formula $$\dfrac{1}{v} - \dfrac{1}{u} = \dfrac{1}{f}$$
$$\dfrac{1}{-100} - \dfrac{1}{-25} = \dfrac{1}{f}$$ $$\implies f =+ \dfrac{100}{3}$$ cm $$ =+ \dfrac{1}{3}$$ m
Power of the lens used $$P = \dfrac{1}{f}$$ where $$f$$ is in meter
$$\therefore$$ $$P = +3$$ $$D$$
Question 4
1 / -0

When Astronauts fly at higher altitude, the sky appears dark because ;

A
Scattering of light does not take place.

B
Scattering of light takes place.

C
Refraction of light takes place.

D
Dispersion of light takes place.

Solution

When sunlight passes through the atmosphere, the fine particles in the air scatter the blue color (shorter wavelengths) more strongly than red. The scattered blue light enters our eyes.
When Astronauts fly at higher altitudes, the sky appears dark because, at very high altitudes, there is no atmosphere. So, there would not have been any scattering of light.
Question 5
1 / -0

When white light is passed through an upside down (inverted) prism then ................

A
White light is obtained

B
Spectrum is obtained with violet colour undergoing maximum and red colour undergoing minimum deviation

C
Spectrum is obtained with red colour undergoing maximum deviation and violet colour undergoing minimum deviation.

D
Light gets blocked

Solution

Here violet undergoes minimum deviation and red undergoes maximum deviation.
Question 6
1 / -0

Focal length of human eye lens is about _____________.

A
2.5 m

B
2.5 cm

C
2.5 mm

D
25 cm

Solution

The focal length of the human eye lens is 2.5 cm.
Question 7
1 / -0

Myopia occurs due to:

A
Increase in the focal length of eye lens

B
Decrease in the distance between retina and lens

C
Decrease in the focal length of the eye lens

D
Increase in the distance between retina and lens

Solution

Myopia is the term used to define short sightedness. Light from a distant object forms an image before it reaches the retina. This is because the eye ball is too large, or the cornea or crystalline lens is too strong. This results in decrease in focal length of eye lens, whereas the distance between retina and lens is always constant.
Question 8
1 / -0

Hypermetropia is a synonym for:

A
Far-sightedness

B
Near-sightedness

C
Bad vision due to old age

D
None of these

Solution

Hypermetropia is also known as far-sightedness. A person with hypermetropia can see distant objects clearly but cannot see nearby objects distinctly.
Myopia is also known as near-sightedness. A person with myopia can see nearby objects clearly but cannot see distant objects distinctly.
The power of accommodation of the eye usually decreases with aging.
Question 9
1 / -0

The ability of eye to focus on both near and far objects is called:

A
Presbyopia

B
Myopia

C
Hypermetropia

D
Power of accommodation

Solution

The ability of the eye lens to adjust its focal length is called as power of accommodation. It helps us to see both near and distant objects clearly. Thus, option $$D$$ is correct.
Question 10
1 / -0

For a myopic (short-sighted) eye, rays from far distant objects are brought to focus at a point:

A
on the retina

B
behind the retina

C
in between eye lens and retina

D
at any position

Solution

In a myopic eye, rays from distant objects are brought to focus at a point in between eye lens and retina. A myopic person can not see distance objects clearly, but is able to see nearby objects clearly.

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Human Eye and Colourful World Test - 18

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Human Eye and Colourful World Test - 18

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Question 1

Convex, + 0.15 D

Convex, +2.25 D

Concave, -0.25 D

Convex, + 0.2 D

Solution

Question 2

+1 D

+2 D

-2 D

-1 D

Solution

Question 3

$$+1\ D$$

$$-1\ D$$

$$+3\ D$$

$$-3\ D$$

Solution

Question 4

Scattering of light does not take place.

Scattering of light takes place.

Refraction of light takes place.

Dispersion of light takes place.

Solution

Question 5

White light is obtained

Spectrum is obtained with violet colour undergoing maximum and red colour undergoing minimum deviation

Spectrum is obtained with red colour undergoing maximum deviation and violet colour undergoing minimum deviation.

Light gets blocked

Solution

Question 6

2.5 m

2.5 cm

2.5 mm

25 cm

Solution

Question 7

Increase in the focal length of eye lens

Decrease in the distance between retina and lens

Decrease in the focal length of the eye lens

Increase in the distance between retina and lens

Solution

Question 8

Far-sightedness

Near-sightedness

Bad vision due to old age

None of these

Solution

Question 9

Presbyopia

Myopia

Hypermetropia

Power of accommodation

Solution

Question 10

on the retina

behind the retina

in between eye lens and retina

at any position

Solution

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