Human Eye and Colourful World Test

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Human Eye and Colourful World Test - 55

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Weekly Quiz Competition

Question 1
1 / -0

A man can see clearly up to $$3\ \textit{metres}$$. Prescribe a lens for his spectacles so that he can see clearly up to $$12\ \textit{metres}$$

A
$$-3/4\ D$$

B
$$3\ D$$

C
$$-1/4\ D$$

D
$$-4\ D$$

Solution

For corrective lens to be used , object distance takes as desired distance person wants to see , so $$u=$$ wants to see $$=-12\ m$$
and image distance taken as distance person initially able to see , so $$v=$$can see $$=-3\ m$$
$$\therefore P=\dfrac 1f=\dfrac 1v-\dfrac 1u =\dfrac{1}{-3}-\dfrac{1}{(-12)}=-\dfrac 14\ D$$
Question 2
1 / -0

A person cannot see distinctly at the distance less than one metre. Calculate the power of the lens that he should use to read a book at a distance of $$25\, cm$$

A
$$+ 3.0\, D$$

B
$$+ 0.125\, D$$

C
$$- 3.0\, D$$

D
$$+ 4.0\, D$$

Solution

As we know,
$$P=\dfrac 1f=-\dfrac 1v+\dfrac 1u=-\dfrac{1}{100}+\dfrac{1}{25}=\dfrac{3}{100}=+3\ D$$
Question 3
1 / -0

In a glass prism, spectrum is produced due to :

A
refraction

B
dispersion

C
scattering

D
diffraction

Solution

The refractive index of many materials (such as glass) varies with the wavelength or color of the light used. This causes light of different colors to be refracted differently and to leave the prism at different angles. this phenomenon known as dispersion.
Question 4
1 / -0

The speeds of red light and yellow light are exactly same

A
in vacuum but not in air

B
in air but not in vacuum

C
in vacuum as well as in air

D
neither in vacuum nor in air.

Solution
Question 5
1 / -0

A normal eye is not able to see objects closer than $$25 \ cm$$ because?

A
The focal length of the eye is $$25 \ cm$$

B
The distance of the retina from the eye-lens is $$25 \ cm$$

C
The eye is not able to decrease the distance between the eye-lens and the retina beyond a limit

D
The eye is not able to decrease the focal length beyond a limit

Solution

For a ‘normal eye’ to visualize the objects it must have a ‘focal length’ of greater than $$25 \ cm$$. If the eye has to focus particles ‘less than $$25 \ cm$$’ then the ciliary muscles of the eyes should expand such as to change its ‘focal length’.

The inability of the eye to decrease the focal length beyond a limit is the reason the eye is not able to see objects closer than $$25 \ cm$$.

Hence option D is correct
Question 6
1 / -0

One can not see through fog because:

A
fog absorbed light

B
light is scattered by the droplets in fog

C
light surfers total reflection by the droplets in the fog

D
the refractive index of fog is in infinity

Solution

The fog certains water droplets, When the reflected light from an object travels through fog, it interacts with the water droplets of the fog and is scattered by them. The scattering of light by fog droplets is not uniform in all directions. also it doesn't reaches to the observer eyes so we can not cannot see through fog.
Question 7
1 / -0

The rising and setting of sun appear red because of :

A
refraction

B
reflection

C
defraction

D
scattering

Solution

The reddish appearance of the sun at sunrise or sunset is due to scattering of light by the molecules of air and other fine particles in the atmosphere.

Hence the option D is the right answer
Question 8
1 / -0

A rainbow can be seen in the sky

A
When the sun is in front of you.

B
When the sun is behind you.

C
When the sun is overhead.

D
Only at the time of sun rise.

Solution

The correct answer is option (b). when the sun is behind you. You can easily see rainbows in the rainy season when the sun is behind you and the sunlight is low.
Question 9
1 / -0

The change that occurs in the eye to see the distant objects cleary is

A
Focal length of the eye lens decreases

B
Curvature of the eye lens increases

C
Focal length of the eye lens increases

D
Culinary muscles of the eye contract

Solution

The human eye lens has the ability to adjust its focal length based on the distance of the object. In order to see the distant object clearly, the lens adjust itself to increase its focal length.
Question 10
1 / -0

The least distance of distinct vision for a young adult with normal vision is

A
$$ 25 \mathrm{m} $$

B
$$ 20 \mathrm{m} $$

C
$$ 25 \mathrm{cm} $$

D
$$ 20 \mathrm{cm} $$

Solution

The least distance of distinct vision for a normal person is $$ 25 \mathrm{cm} $$.

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Re-Attempt Weekly Quiz Competition

Human Eye and Colourful World Test - 55

Result

Human Eye and Colourful World Test - 55

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SHARING IS CARING

Question 1

$$-3/4\ D$$

$$3\ D$$

$$-1/4\ D$$

$$-4\ D$$

Solution

Question 2

$$+ 3.0\, D$$

$$+ 0.125\, D$$

$$- 3.0\, D$$

$$+ 4.0\, D$$

Solution

Question 3

refraction

dispersion

scattering

diffraction

Solution

Question 4

in vacuum but not in air

in air but not in vacuum

in vacuum as well as in air

neither in vacuum nor in air.

Solution

Question 5

The focal length of the eye is $$25 \ cm$$

The distance of the retina from the eye-lens is $$25 \ cm$$

The eye is not able to decrease the distance between the eye-lens and the retina beyond a limit

The eye is not able to decrease the focal length beyond a limit

Solution

Question 6

fog absorbed light

light is scattered by the droplets in fog

light surfers total reflection by the droplets in the fog

the refractive index of fog is in infinity

Solution

Question 7

refraction

reflection

defraction

scattering

Solution

Question 8

When the sun is in front of you.

When the sun is behind you.

When the sun is overhead.

Only at the time of sun rise.

Solution

Question 9

Focal length of the eye lens decreases

Curvature of the eye lens increases

Focal length of the eye lens increases

Culinary muscles of the eye contract

Solution

Question 10

$$ 25 \mathrm{m} $$

$$ 20 \mathrm{m} $$

$$ 25 \mathrm{cm} $$

$$ 20 \mathrm{cm} $$

Solution

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