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The Human Eye & the Colorful World - 2 - UPSC MCQ


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20 Questions MCQ Test Science & Technology for UPSC CSE - The Human Eye & the Colorful World - 2

The Human Eye & the Colorful World - 2 for UPSC 2024 is part of Science & Technology for UPSC CSE preparation. The The Human Eye & the Colorful World - 2 questions and answers have been prepared according to the UPSC exam syllabus.The The Human Eye & the Colorful World - 2 MCQs are made for UPSC 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for The Human Eye & the Colorful World - 2 below.
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The Human Eye & the Colorful World - 2 - Question 1

When light rays enter the eye, most of the refraction occurs at the

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 1

When light enters the eye, most of the refraction takes place at the outer surface of the cornea. The crystalline lens only makes some finer adjustment.

The Human Eye & the Colorful World - 2 - Question 2

The focal length of the eye lens increases when eye muscles

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 2

Cilliary muscles modify the curvature of eye lens. When eye muscles are relaxed, eye lens becomes thinner thereby are relaxed, eye lens becomes thinner thereby increase in the focal length of eye lens.

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The Human Eye & the Colorful World - 2 - Question 3

The amount of light entering the eye is controlled by

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 3

What is the function of Iris and Pupil? - Human Eye - Teachoo
Iris controls the amount of light entering the eye.
The Iris automatically adjust the size of the pupil according to the intensity of light received by the eye.

If it is daytime, the iris contracts the pupil and reduces the amount of light entering.
If it is night, iris expands the pupil so that more light may enter the eye.

The Human Eye & the Colorful World - 2 - Question 4

A normal eye is not able to see objects closer than 25 cm because:

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 4

The correct option is the eye is not able to decrease the focal length beyond a limit.
A normal eye cannot focus on objects closer than 25 cm away because the eye cannot reduce its focal length any farther since the ciliary muscles are most stretched up to that point.
After that, the muscles are not strained at all. This means that the focal length cannot be smaller.
Therefore, at distances of less than 25 cm, the eye cannot see objects clearly.

The Human Eye & the Colorful World - 2 - Question 5

When the light is very bright

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 5

When the light is very bright the iris makes the pupil contract so as to control the quantity of light entering the eye.

The Human Eye & the Colorful World - 2 - Question 6

The bluish colour of water in deep sea is due to

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 6

What is Scattering of light? | STEM LEARNING
The fine water molecules mainly scatter blue light due to its shorter wavelength.

The Human Eye & the Colorful World - 2 - Question 7

Eye lens form the image of an object situated in front of it at the retina. The image formed is

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 7

The image of an object situated in front of eye is formed on the retina. The image formed is a real, inverted and diminished image

The Human Eye & the Colorful World - 2 - Question 8

The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 8

Red colour has longer wavelength so least scattered by smoke or fog.

The Human Eye & the Colorful World - 2 - Question 9

The range of vision of a normal human eye is from

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 9

Range of vision for a normal human eye is between its near point and far point i.e, from 25cm to infinity.

The Human Eye & the Colorful World - 2 - Question 10

The clear sky appears blue because

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 10

Violet and blue colour have shorter wavelength.
So, they scattered more than lights of other colour by the molecules present in the atmosphere.

The Human Eye & the Colorful World - 2 - Question 11

The change in focal length of eye lens, so as to focus the image of objects situated at varying distance in front of eye, is done by the action of the

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 11


To focus the objects, situated at different distances from the eye, distinctly at the retina the eye lens adjusts its focal length. This adjustment of focal length of eye lens is achieved by the contraction/relaxation of the ciliaiy muscles.

The Human Eye & the Colorful World - 2 - Question 12

Twinkling of stars is due to atmospheric

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 12

Twinkling of star is due to atmospheric refraction of starlight caused by the gradual change in refractive index of different air layers at different height, the apparent position of star keeps on changing.

The Human Eye & the Colorful World - 2 - Question 13

At noon the sun appears white as

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 13

At noon, the sun is at top and the light rays coming from the sun have to travel lens distance hence, all colours get scattered very less even blue and violet.

The Human Eye & the Colorful World - 2 - Question 14

A student sitting on last bench in a classroom cannot see clearly words written on the blackboard. He is suffering from

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 14

A student, who cannot read words written on blackboard from the last bench of his class room, is suffering from the myopia or short-sightedness defect of vision of eye.

The Human Eye & the Colorful World - 2 - Question 15

A prism ABC (with BC as base) is placed in different orientations. A narrow beam of white light is incident on the prism as shown in figure. In which of the following cases, after dispersion, the third colour from the top corresponds to the colour of the sky?

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 15

In figure (a) base BC of the prism is at the bottom, then violet colour lies at the bottom but in figure (b), the base BC is at the top, then violet would be at the top after dispersion, and third colour would be blue.

The Human Eye & the Colorful World - 2 - Question 16

A person cannot see distinctly objects kept beyond 80 cm. This defect of vision is known as

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 16


A person, who cannot see objects placed beyond 80 cm distinctly, is suffering from the myopia or short-sightedness defect of vision of eye.

The Human Eye & the Colorful World - 2 - Question 17

A girl can see distant objects clearly but cannot see an object situated close to her eye. She is suffering with

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 17

A girl who can see distant objects clearly but is unable to see clearly the objects situated close to her eye, is suffering from hypermetropia or long-sightedness defect.

The Human Eye & the Colorful World - 2 - Question 18

A student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his textbook. Which of the following statements is correct ?

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 18

A student sitting on the last bench of class can read the letters written on the blackboard. It means his farsight is normal. However, he cannot read the letters written in his textbook distinctly. It means he is suffering from long-sightedness (hypermetropia) and the near point of his eye has receded away

The Human Eye & the Colorful World - 2 - Question 19

A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 19

Person cannot see distant objects clearly. So he is suffering from myopia. The defect is corrected by using concave lens of power

The Human Eye & the Colorful World - 2 - Question 20

One cannot see through the fog, because

Detailed Solution for The Human Eye & the Colorful World - 2 - Question 20

Objects are not visible through the fog because droplets scatter the light rays.

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