Human Eye and Colourful World Test

Result

Human Eye and Colourful World Test - 31

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following options correctly describe respective image?

A
A short-sighted eye corrected by a convex lens.

B
A short sighted eye corrected by concave lens.

C
A healthy eye.

D
A short sighted eye corrected by convex lens.

Solution

A: Person cannot see far objects clearly and hence is short-sighted. No correction is used.
B: Direction of light rays are wrong and hence the image shown is not possible.
C: The given eye is able to focus an object at certain distance on its retina. Hence, it may be a healthy eye.
D: Light rays not passing through the lens is focussed on the retina. Hence, it may be a healthy eye and needs no correction.
Question 2
1 / -0

One cannot see through fog because:

A
fog absorbs light

B
light is scattered away by the droplets in fog

C
light suffers total internal reflection at the droplets in fog

D
the refractive index of fog is infinity

Solution

One cannot see through fog because light is scattered away by the droplets in fog.
Question 3
1 / -0

Long-sightedness is caused by the eyeball being too short. It can be corrected by the use of a:

A
convergent lens

B
plane mirror

C
divergent lens

D
None of these

Solution

Long-sightedness is caused by the eyeball being too short. In such an eye, image of nearby objects are formed beyond the retina. It can be corrected by the use of a convergent lens of proper power which converges light rays and hence brings position of image to the retina.
Question 4
1 / -0

The formation of mirage is due to :

A
Reflection

B
Refraction

C
Dispersion

D
Total internal reflection

Solution

Mirage is caused due to total internal reflection of light by the various layers of air. It is an optical illusion which is responsible for the appearance of water layer at short distances in a desert or on road.
Question 5
1 / -0

Which of the following lens is used to correct hypermetropia?

A
Convex lens

B
Concave lens

C
Cylindrical lens

D
None of these

Solution

In Hypermetropia, the image of a nearby object is formed behind the retina. By placing a convex (plus powered) lens in front of a hypermetropic eye, the image is moved closer to the lens and is focussed correctly on the retina.
Question 6
1 / -0

A mirage takes place due to..........

A
Reflection

B
Refraction

C
Total internal reflection

D
Both (2) and (3)

Solution

Normally, light waves from the sun travel straight through the atmosphere to your eye. But, light travels at different speeds through hot air and cold air. Mirages happen when the ground is very hot and the air is cool. The hot ground warms a layer of air just above the ground.When the light moves through the cold air and into the layer of hot air it is refracted (bent).A layer of very warm air near the ground refracts the light from the sky nearly into a U-shaped bend. Our brain thinks the light has traveled in a straight line. Our brain doesn't see the image as bent light from the sky. Instead, our brain thinks the light must have come from something on the ground.
Question 7
1 / -0

Which of the following lens is used to correct myopia?

A
Convex lens

B
Concave lens

C
Cylindrical lens

D
None of these

Solution

In Myopia, the image of a nearby object is formed ahead of the retina. By placing a concave (negative powered) lens in front of a myopic eye, the image is moved farther to the lens and is focussed correctly on the retina.
Question 8
1 / -0

A mirage occurs because :

A
the hot ground acts like a mirror

B
the refractive index of atmosphere decreases with height

C
the refractive index of atmosphere increases with height

D
the refractive index remains constant with height

Solution

A mirage occurs because the refractive index of the atmosphere increases with height.

Mirages are examples of total internal reflection. The conditions most likely to produce a mirage in the desert would be a layer of hot air lying immediately above the ground with cooler air above it (this is quite usual during the day because the ground becomes so hot). The refractive index keeps on increasing as we go up. The incident light from the object gets total internally reflected and reaches the observer's eyes if the angle of incidence is greater than the critical angle of the adjacent layer. Thus we see a reflection of the sky and other objects on the ground.
Question 9
1 / -0

A man wear glasses of focal length $$f=+1\ m.$$

A
If he is far-sighted

B
If he is near-sighted

C
If his vision is normal

D
None of these

Solution

Given,
Focal length of the glasses, $$f=+1\ m$$
For a convex lens, the focal length is always positive.
Hypermetropia is also known as farsightedness. A person with hypermetropia can see distant objects clearly but cannot see nearby objects distinctly. This defect can be corrected by using a convex lens of appropriate power
Question 10
1 / -0

In case of hypemetropia

A
The image of near objects is formed in front of retina

B
The image of near objects is formed behind the retina

C
A concave lens should be used for correction

D
A convex lens cannot be used for correction

Solution

Hypermetropia or long-sightedness:
Long-sightedness, also known as hypermetropia or hyperopia is a common vision disorder. It results from the overall power of the eye not being strong enough, or the length of the eye being too short.