Human Eye and Colourful World Test

Result

Human Eye and Colourful World Test - 29

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Weekly Quiz Competition

Question 1
1 / -0

The focal length of the eye lens increases when eye muscles:

A
are relaxed and lens becomes thinner.

B
contract and lens becomes thicker.

C
are relaxed and lens becomes thicker.

D
contract and lens becomes thinner.

Solution

When the muscles are relaxed, the lens becomes thin. Thus, its focal length increases, hence, option $$A$$ is correct
Question 2
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Which of the following phenomena contributes significantly to the reddish appearance of the sun at sunrise or sunset?

A
Dispersion of light

B
Scattering of light

C
Total internal reflection of light

D
Reflection of light from the earth

Solution

We see red colour of the sun at sunrise or sunset as the sun at horizon and light rays need to travel a greater distance. In the process of scattering, violet, blue and green rays in the original sunlight are removed and the transmitted beam has yellow and red dominant.
Question 3
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The bluish colour of water in deep sea is due to:

A
the presence of algae and other plants found in water.

B
reflection of sky in water.

C
scattering of light.

D
absorption of light by the sea.

Solution

As we look deep into the sea in a direction away from the sun as the blue light is more scattered more than red. The light reaching our eyes has more of violet and blue and hence the deep sea appears blue.
Question 4
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A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her?

A
Doctor advises her to use a convex lens of appropriate power.

B
Doctor advises her to use a concave lens of appropriate power.

C
Doctor advises her to use a plane mirror of appropriate power.

D
Doctor advises her to use a plano convex lens of appropriate power.

Solution

The student is suffering from myopia (near sightedness). Doctor advises her to use a concave lens of appropriate power to correct this defect.
Question 5
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Which of the following statement is correct?

A
A person with myopia can see distant objects clearly

B
A person with hypermetropia can see nearby objects clearly

C
A person with myopia can see nearby objects clearly

D
A person with hypermetropia cannot see distant objects clearly

Solution

A person suffering from myopia cannot see distant object distinctly. Far point of the eye is shifted to a smaller distance. Beyond the far point, he cannot see the object distinctly. But the near point remain unaffected.
Question 6
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Directions For Questions

A person needs a lens of power 4.5 D for correction of her vision.

...view full instructions

What kind of defect in vision is she suffering from?

A
Myopia

B
Hypermetropia

C
Astigmatism

D
None of these

Solution

Power of $$P=4.5D \Rightarrow f=\cfrac{1}{4.5}$$
$$f=0.22m =22cm$$
Positive focal length means that the lens is a convex lens.
Hence person should have trouble in seeing things close to his eyes.
He is suffering from long-sighted-ness that is $$hypermetropia$$.

Answer-(B)
Question 7
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Match the entries in Column I with those in Column II correctly.

A
i - s, ii - r, iii - q, iv - p

B
i - q, ii - s, iii - p, iv - r

C
i - r, ii - p, iii - s, iv - q

D
i - q, ii - r, iii - s, iv - p

Solution
Question 8
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The clear sky appears blue because:

A
blue light gets absorbed in the atmosphere.

B
ultraviolet radiations are absorbed in the atmosphere.

C
violet and blue lights get scattered more than all other colours by the atmosphere.

D
light of all other colours is scattered more than the violet and blue colour lights by the atmosphere.
Question 9
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Why does the pupil of a human eye appear black?

A
No light gets refracted from it.

B
No light gets dispersed from it.

C
No light gets scattered from it.

D
No light is reflected from it.

Solution

The pupil of a human eye appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffused reflections within the eye and hence they miss escaping the narrow pupil.
Question 10
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How can we explain the reddish appearance of sun at sunrise or sunset?

A
Scattering of blue light is more than the scattering of red light

B
Scattering of red light is more than the scattering of blue light

C
Intensity of sun reduces during sunrise and sunset

D
Due to the view angle, it appears blue

Solution

During sunrise or sunset, the light has to pass through greater distance in the atmosphere. The blue light is removed as it gets scattered the most while the red colour is less scattered and reaches the observer. Thus, we find reddish colour of the sun during sunrise or sunset.