Human Eye and Colourful World Test

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Human Eye and Colourful World Test - 59

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Weekly Quiz Competition

Question 1
1 / -0

Anil, an $$8^{th}$$ grade student, was asked to draw a figure explaining how the mammalian eye collects and focuses light, converting it into electrical signals. Which of the following flow charts correctly represents the process?

A
Light $$\rightarrow$$ Cornea $$\rightarrow$$ Aqueous humor $$\rightarrow$$ Pupil $$\rightarrow$$ Lens $$\rightarrow$$ Vitreous humor $$\rightarrow$$ Retina $$\rightarrow$$ Action potentials in neurons $$\rightarrow$$ Optic nerve $$\rightarrow$$ Brain.

B
Light $$\rightarrow$$ Sclera $$\rightarrow$$ Vitreous humor $$\rightarrow$$ Pupil $$\rightarrow$$ Lens $$\rightarrow$$ Aqueous humor $$\rightarrow$$ Retina $$\rightarrow$$ Action potentials in neurons $$\rightarrow$$ Optic nerve Brain.

C
Light $$\rightarrow$$ Sclera $$\rightarrow$$ Cornea $$\rightarrow$$ Aqueous humor $$\rightarrow$$ Pupil $$\rightarrow$$ Lens $$\rightarrow$$ Vitreous humor $$\rightarrow$$ Retina $$\rightarrow$$ Action potentials in neurons $$\rightarrow$$ Optic nerve $$\rightarrow$$ Brain.

D
Light $$\rightarrow$$ Cornea $$\rightarrow$$ Aqueous humor $$\rightarrow$$ Iris $$\rightarrow$$ Lens $$\rightarrow$$ Vitreous humor $$\rightarrow$$ Retina $$\rightarrow$$ Action potentials in neurons $$\rightarrow$$ Optic nerve $$\rightarrow$$ Brain.
Question 2
1 / -0

The ciliary muscles of eye control the curvature of the lens in the eye and hence and alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means, radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about $$25\ cm$$ for a grown up person.
A person can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around $$25\ cm$$.
A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image of the spectacle lens becomes object for the eye lens and whose image is formed on the retina.
The number of spectacle lens used for the remedy of eye defect is decided by the power of the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is $$+3D$$ (converging lens of focal length $$100/3\ cm$$), then number of lens will be $$+3$$.
For all the calculations required, you can used the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens.
A far sighted man cannot see objects clearly unless they are at least $$100 \ cm$$ from his eyes. The number of the spectacle lenses that will make his range of clear vision equal to an average grown up person will be

A
$$+1$$

B
$$1$$

C
$$+3$$

D
$$3$$

Solution

For the far-sighted man, lens should make image of the nearby object at distances at or beyond $$100\ cm$$.

For grown up person least distance is $$25\ cm$$.

Hence, image of an object at $$25 \ cm$$ should form at $$100 \ cm$$.
For lens, $$u = -25, v = -100$$

Using the lens' formula,
$$\dfrac{1}{f} = \dfrac{1}{v} - \dfrac{1}{u}$$

$$\dfrac {1}{f} = \dfrac {1}{-100} - \dfrac {1}{(-25)} \Rightarrow \dfrac {1}{f} = \dfrac {3}{100} \ cm^{-1}$$

Since, Power $$ P = \dfrac{1}{f} = \dfrac{3}{100} \ cm^{-1} = 3 \ m^{-1} = 3 \ D$$

Hence, $$P = +3 \ D$$ So no. of spectacle is $$= +3$$.
Question 3
1 / -0

The process of re-emission of absorbed light in all directions with different intensities by the atom or molecule is called ____________.

A
Scattering of light

B
Dispersion of light

C
Reflection of light

D
Refraction of light

Solution

The process of absorbed light in all possible directions with different intensities and frequencies by an atom or a molecule is called the scattering of light. When a beam of light strikes such fine particles, the path of the beam becomes visible. The light reaches us, after being reflected diffusely by these particles.
Question 4
1 / -0

What is the color of the emergent ray of light when two prisms are placed besides each other in a way that the second is inverted?

A
Red

B
Green

C
White

D
Blue

Solution

Isaac Newton was the first person to split sunlight into seven colors using a glass prism. When he tried to split the band of colors further using a second prism placed in the inverted position as compared to that of the first, he observed that the emergent ray was white colored. This gave him an idea that sunlight is made up of 7 colors and any other light that gives a spectrum similar to that of sunlight is often referred to as white light.
Question 5
1 / -0

If red and violet colours are passing through the same glass sheet simultaneously then the relation between their velocities will be:

A
$$v_r\,=\, v_v$$

B
$$v_r\, <\, v_v$$

C
$$v_r\,>\, v_v$$

D
None of these
Question 6
1 / -0

Sky looks bright from the earth on a sunny day but from any space station it is dark because

A
no reflecting/scattering medium in space

B
no luminous object in space

C
no natural source of light in space

D
eye deficiency

Solution

Due to the phenomena of scattering of light by the particles present in the atmosphere, the sky looks bright from the earth on a sunny day. Since, there is no reflecting/scattering medium in space, it looks dark from the space station.

Hence, option A is correct.
Question 7
1 / -0

A man can see objects clearly up to $$3 m$$. What type of lens he should use in order to see clearly up to $$12 m$$?

A
Convex lens, $$f= 4 m$$

B
Concave lens, $$f= 4 m$$

C
Convex lens, $$f= -4 m$$

D
Concave lens, $$f= -4 m$$

Solution

Clearly, the lens used should be the concave lens.
Actual far point
$$u=-12m$$
Far point of the person,
$$v=-3m$$
We have lens formula,

$$\cfrac { 1 }{ v } -\cfrac { 1 }{ u } =\cfrac { 1 }{ f } $$

$$\Rightarrow \cfrac { 1 }{ -3 } +\cfrac { 1 }{ 12 } =\cfrac { 1 }{ f } $$

$$\Rightarrow f = - 4m$$

Thus a concave lens of focal length $$4\ m$$ is used.
Question 8
1 / -0

A man can see distinctly from a distance of $$0.5 m$$. If he wants to read a book placed at a distance of $$25 cm$$, then what kind of lens should he use?

A
Convex lens with focal length of $$-50 cm$$

B
Concave lens with focal length of $$-50 cm$$

C
Convex lens with focal length of $$50 cm$$

D
Concave lens with focal length of $$50 cm$$

Solution

Since given that;

$$u = 0.5m = 50cm$$

$$v = 25cm$$

To find $$f$$, we know that

$$\cfrac { 1 }{ v } -\cfrac { 1 }{ u } =\cfrac { 1 }{ f } $$

$$\cfrac { 1 }{ 50 } -\cfrac { 1 }{ 25 } =\cfrac { 1 }{ f } $$

$$\cfrac { 1 }{ f } =\cfrac { -1 }{ 50 } $$

$$f = 50cm$$

Hence a concave lens of focal length $$50 cm$$ is used.
Question 9
1 / -0

Read the given statements and mark the correct option.
Statement 1 : Abeam of white light gives a spectrum on passing through a hollow prism.
Statement 2 : Speed of light outside the hollow prism is different from the speed of light inside the hollow prism.

A
Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1.

B
Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1.

C
Statement 1 is true but statement 2 is false.

D
Both statements 1 and 2 are false.

Solution
Question 10
1 / -0

In Section A, defects of eye are given, in Section B, effects arising due to defects are given and in section C, remedies are given using lenses. Find the correct pair.
Section A
Section B
Section C
1. Myopia
(x) Focal length increases
(a) Bifocal lens
2. Hypermetropia
(y)Focal length decreases
(b) Concave lens
3. Presbyopia
(z) Power of accommodation decreases
(c) Convex lens

A
(1 - y - b), (2 - x - c), (3 - z - a)

B
(1 - z - b), (2 - z - b), (3 - y - b)

C
(1 - x - a), (2 - y - c), (3 - x - a)

D
(1 - y - a), (2 - x - a), (3 - z - c)

Solution

1. Myopia is a condition of the eye where light focuses in front of the retina i.e. focal length decreases. A concave lens (minus powered) is placed in front of a myopic eye, moving the image back to the retina and clarifying the image.
Match 1----> y -----> b

2. Hypermetropia, is a condition of the eye in which light is focused behind, instead of on the retina. A convex lens (plus powered) is placed in front of a hypermetropic eye, moving the image back to the retina and clarifying the image.
Match 2----> x -----> c

3. Presbyopia is caused by loss of elasticity of the lens of the eye so it does not focus near as well as far point ie Power of accommodation decreases, occurring typically in middle and old age. Presbyopia can be treated using bifocal lenses.
Match 3----> z -----> a

So, correct answer is A.

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Re-Attempt Weekly Quiz Competition

Section A	Section B	Section C
1. Myopia	(x) Focal length increases	(a) Bifocal lens
2. Hypermetropia	(y)Focal length decreases	(b) Concave lens
3. Presbyopia	(z) Power of accommodation decreases	(c) Convex lens

Human Eye and Colourful World Test - 59

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Human Eye and Colourful World Test - 59

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Question 1

Light $$\rightarrow$$ Cornea $$\rightarrow$$ Aqueous humor $$\rightarrow$$ Pupil $$\rightarrow$$ Lens $$\rightarrow$$ Vitreous humor $$\rightarrow$$ Retina $$\rightarrow$$ Action potentials in neurons $$\rightarrow$$ Optic nerve $$\rightarrow$$ Brain.

Light $$\rightarrow$$ Sclera $$\rightarrow$$ Vitreous humor $$\rightarrow$$ Pupil $$\rightarrow$$ Lens $$\rightarrow$$ Aqueous humor $$\rightarrow$$ Retina $$\rightarrow$$ Action potentials in neurons $$\rightarrow$$ Optic nerve Brain.

Light $$\rightarrow$$ Sclera $$\rightarrow$$ Cornea $$\rightarrow$$ Aqueous humor $$\rightarrow$$ Pupil $$\rightarrow$$ Lens $$\rightarrow$$ Vitreous humor $$\rightarrow$$ Retina $$\rightarrow$$ Action potentials in neurons $$\rightarrow$$ Optic nerve $$\rightarrow$$ Brain.

Light $$\rightarrow$$ Cornea $$\rightarrow$$ Aqueous humor $$\rightarrow$$ Iris $$\rightarrow$$ Lens $$\rightarrow$$ Vitreous humor $$\rightarrow$$ Retina $$\rightarrow$$ Action potentials in neurons $$\rightarrow$$ Optic nerve $$\rightarrow$$ Brain.

Question 2

$$+1$$

$$1$$

$$+3$$

$$3$$

Solution

Question 3

Scattering of light

Dispersion of light

Reflection of light

Refraction of light

Solution

Question 4

Red

Green

White

Blue

Solution

Question 5

$$v_r\,=\, v_v$$

$$v_r\, <\, v_v$$

$$v_r\,>\, v_v$$

None of these

Question 6

no reflecting/scattering medium in space

no luminous object in space

no natural source of light in space

eye deficiency

Solution

Question 7

Convex lens, $$f= 4 m$$

Concave lens, $$f= 4 m$$

Convex lens, $$f= -4 m$$

Concave lens, $$f= -4 m$$

Solution

Question 8

Convex lens with focal length of $$-50 cm$$

Concave lens with focal length of $$-50 cm$$

Convex lens with focal length of $$50 cm$$

Concave lens with focal length of $$50 cm$$

Solution

Question 9

Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1.

Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1.

Statement 1 is true but statement 2 is false.

Both statements 1 and 2 are false.

Solution

Question 10

(1 - y - b), (2 - x - c), (3 - z - a)

(1 - z - b), (2 - z - b), (3 - y - b)

(1 - x - a), (2 - y - c), (3 - x - a)

(1 - y - a), (2 - x - a), (3 - z - c)

Solution

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