Light (Part -1)

Total Questions: 50

31. Optical fiber works on which of the following principles of light? [S.S.C. Online Graduation Level (T-I) 11.08.2017 (Shift-II)]

(a) reflection
(b) diffraction
(c) refraction
(d) total internal reflection

Correct Answer: (d) total internal reflection

Solution:Optical fibers are extremely thin cylindrical hollow tubes made of glass (silica) or plastic, which work on the principle of total internal reflection of light.

There is no loss of light energy in them.

What are Fiber Optics and How Do They Work? | Coherent

32. Stars twinkle but planets do not twinkle because________. [S.S.C. Online Graduation Level (T-I) 29.08.2016 (Shift-I)]

(a) they emit light of a constant intensity.
(b) their distance from the earth does not change with time.
(c) they are very far away from the earth resulting in decrease in intensity of light.
(d) they are nearer to the earth and hence we receive a greater amount of light and therefore minor variations in intensity are not noticeable.

Correct Answer: (d) they are nearer to the earth and hence we receive a greater amount of light and therefore minor variations in intensity are not noticeable.

Solution:

Stars twinkle but planets do not twinkle because stars are effectively point sources of light due to their enormous distance from Earth, while planets appear as tiny discs (extended sources) in the sky.

More specifically:

Stars are very far away, so their light arrives as a single point. Atmospheric turbulence causes rapid fluctuations in the star's apparent position and brightness, making it appear to twinkle.
Planets are much closer, so their apparent size is larger (they have an angular diameter). The atmospheric turbulence affects different parts of the planet's disk differently, averaging out the fluctuations, so planets generally appear steady and do not twinkle.

Q&A: Why Stars Twinkle – SKY LIGHTS

33. The splitting of light into different colors is called ______ . [S.S.C. Online CHSL (T-I) 31.01.2017 (Shift-II)]

(a) Separation
(b) Deviation
(c) Dispersion
(d) Reflection

Correct Answer: (c) Dispersion

Solution:The splitting of light into different colors when light passes through a prism is called dispersion or diffusion.

Among the colors obtained from sunlight, the violet color has the highest deflection and the red color has the least deflection.

34. What is the colour of the light emitted by the sun? [S.S.C. Online Graduation Level (T-I) 5.03.2020 (Shift-I)]

(a) White
(b) Red
(c) Yellow
(d) Orange

Correct Answer: (a) White

Solution:The light emitted by the Sun is white in colour.

In fact, there are seven colors

violet,
blue,
sky,
green,
yellow,
orange,
and red colors

emitted by a white hot body. Their mixed color is white. Hence the sunlight appears white.

35. The splitting of white light into its component colours is called_______ . [S.S.C. JE Mechanical Exam 27.10.2020 (Shift-II)]

(a) Sublimation
(b) Combustions
(c) Dispersion
(d) Condensation

Correct Answer: (c) Dispersion

Solution:The splitting of light into different colors when light passes through a prism is called dispersion or diffusion.

Among the colors obtained from sunlight, the violet color has the highest deflection and the red color has the least deflection.

36. In the absence of the earth's atmosphere, sky would appear_________. [S.S.C. Online Graduation Level (T-I) 30.08.2016 (Shift-II)]

(a) blue
(b) deep red
(c) white
(d) black

Correct Answer: (d) black

Solution:

In the absence of the Earth's atmosphere, the sky would appear completely black.

This is because there would be no air molecules to scatter sunlight, so during the daytime, the sky would look like the dark, star-filled space seen from outer space.

37. The colour of the clear sky is blue due to the phenomenon of: [S.S.C. Online MTS (T-I) 18.10.2021 (Shift-I)]

(a) refraction of light
(b) reflection of light
(c) dispersion of light
(d) scattering of light

Correct Answer: (d) scattering of light

Solution:The rays of light (white light of the Sun) in the clear sky go through the process of scattering due to the very fine particles of dust present in the air, in which the scattering of blue light of shorter wavelength is maximum due to the light of this color the sky appear blue.

38. Which of the following colours of a rainbow has the shortest wavelength? [S.S.C. JE Civil Exam 30.10.2020 (Shift-I)]

(a) Violet
(b) Blue
(c) Indigo
(d) Red

Correct Answer: (a) Violet

Solution:The colour of a rainbow that has the shortest wavelength is violet.

Order of Colors in a Rainbow:

From the outer edge to the inner edge, the colors appear in this order:

Red (longest wavelength) → Orange → Yellow → Green → Blue → Indigo → Violet (shortest wavelength)

39. Which of the following colours CANNOT be found in a rainbow? [S.S.C. JE Electrical Exam 28.10.2020 (Shift-I)]

(a) Pink
(b) Orange
(c) Green
(d) Yellow

Correct Answer: (a) Pink

Solution:Pink color cannot be found in a Rainbow.

The colors in a rainbow, arranged from the outer edge to the inner edge, are:

Red
Orange
Yellow
Green
Blue
Indigo
Violet

These seven colors are often remembered by the acronym ROYGBIV.

40. Rainbow is a natural phenomenon of _______ of light. [S.S.C. Online MTS (T-I) 6.10.2017 (Shift-I)]

(a) Reflection
(b) Refraction
(c) Diffusion
(d) Dispersion
(e) (a),(b) & (d)

Correct Answer: (e) (a),(b) & (d)

Solution:A Rainbow is formed due to the

reflection,
total internal reflection,
refraction,
and color dispersion of light

in water droplets.

A rainbow is made up of seven colors

purple,
violet,
blue,
green,
yellow,
orange,
and red,

with usually red and violet at the edges, while other colors are in the middle.
Of these colors, the shortest wavelength is purple and the longest wavelength is red. Due to this property of red color, it is used in traffic signals.

RAINBOW: AN OPTICAL PHENOMENA – INDIA METEOROLOGICAL DEPARTMENT

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