Human Eye and Colourful World Test

Result

Human Eye and Colourful World Test - 40

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Weekly Quiz Competition

Question 1
1 / -0

Angle of deviation is between :

A
Real and virtual image

B
Incident and emergent ray

C
Plane of reflection and plane of incidence

D
None of the above

Solution

Angle of deviation is between Incident and emergent ray.
Question 2
1 / -0

The film of camera is compared to which part of human eye?

A
Lens

B
Retina

C
Iris

D
Choroid

Solution

Film of a camera acts as a screen where image is formed. Similarly, at retina , image is formed that means it acts like a film of camera.
Question 3
1 / -0

Mirages are observed in deserts due to the phenomenon of

A
Interference of light and reflection of light

B
Total internal reflection of light and refraction of light

C
Scattering of light and dispersion of light

D
Double refraction of light
Question 4
1 / -0

Which of the following is not a characteristics of a concave lens?

A
Thick at the edges and thin in the middle.

B
Used to correct shortsightedness

C
A diverging lens

D
Used to correct longsightedness

Solution

We use convex lens to correct long sightedness or hypermetropia, not concave.
Concave lens is a diverging lens and is thick at edge and thin at middle.
Question 5
1 / -0

In hypermetropia, the image of near object is formed :

A
Before the retina

B
On retina

C
Behind the retina

D
Above the retina

Solution

In hypermetropia, the image is formed behind the retina. It is also known as far-sightedness as only the far away objects are clearly visible. Convex lens is used to correct this defect.
Question 6
1 / -0

In myopia, the image of distant object is formed :

A
Before the retina

B
On the retina

C
Behind the retina

D
Above the retina

Solution

Myopia means near-sightedness, the image doesn't form at retina but at a place before retina. Concave lens is used to correct this defect.
Question 7
1 / -0

The least distance of distinct vision for a defective eye is $$75$$ cm. What should be the focal length of the lens which will be used to read a book clearly at $$25$$ cm?

A
$$75\ cm$$

B
$$25\ cm$$

C
$$37.5\ cm$$

D
$$150\ cm$$

Solution

Given,
Near point of defective (hypermetropic eye) $$= 75\ cm$$
Near point of normal eye $$= 25\ cm$$
object distance, $$u = -25\ cm$$
image distance, $$v = -75\ cm$$

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

$$\dfrac{1}{f} = \dfrac{1}{-75} - \dfrac{1}{-25} = \dfrac{-1 + 3}{75}$$

$$\dfrac{1}{f} = \dfrac{2}{75}$$

$$f = 37.5\ cm$$
Question 8
1 / -0

For a normal eye, the far point is at infinity and the near point of distinct vision is about $$25\ cm$$ in front of the eye. The cornea of the eye provides a converging power of about $$40$$ dioptres, and the least converging power of the eye - lens behind the cornea is about $$20$$ dioptres. From this rough data estimate the range of accommodation (i.e., the range of converging power of the eye-lens) of a normal eye.

A
$$10$$ to $$14\ D$$

B
$$20$$ to $$24\ D$$

C
$$28$$ to $$32\ D$$

D
$$14$$ to $$18\ D$$

Solution

To see object at infinity, eye uses its least converging power.
Power of eye lens, $$P=40+20=60D$$
Power of eye lens is $$1/f\Rightarrow f=5/3 cm$$
To focus on object at the near point, object distance $$u=-d=-25$$ cm
Focal length of eye lens is distance between the cornea and the retina.
Image distance, $$v=5/3\ cm$$
$$\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f_1}\Rightarrow f_1=16/25cm^{-1}$$
Power is $$100/f_1=64D$$
power of eye lens is $$64-40=24D$$.
Question 9
1 / -0

The muscles of a normal eye are least strained when the eye is focused on an object .....

A
Far away from the eye

B
Very close to the eye

C
At about $$25$$ cm from the eye

D
At about $$1$$ m from the eye
Question 10
1 / -0

Assertion: Blue colour of sky appears due to scattering of blue colour.
Reason: Blue colour has shortest wave length in visible spectrum.

A
both assertion and reason are true and reason is the correct explanation of assertion

B
both assertion and reason are true but the reason is not the correct explanation of assertion

C
assertion is true but reason is false

D
both the assertion and reason are false

E
reason is true but assertion is false

Solution

Blue colour of sky is due to scattering of blue colour to the maximum extent by dust particles. Blue colour appears to be coming from the sky. Blue colour has the least wavelength .