Light MCQ question and answer with solution

21

. . . . . . . . is used in yellow lamp street lights?

A) neon B) nitrogen C) phosphorus D) sodium

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Answer & Solution

Answer: Option D

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22

A curved mirror where the reflecting surface is curved inwards is called a

A) concave mirror B) plano-convex mirror C) plane mirror D) convex mirror

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Answer & Solution

Answer: Option A

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23

Which of the following statements about optical microscope is/are correct?
1. Both the eyepiece and objective of a microscope are convex lenses.
2. The magnification of a microscope increases with increases in focal length of the objective.
3. The magnification of a microscope depends upon the length of the microscope tube.
4. The eyepiece of a microscope is a concave lens.
Select the correct answer:

A) 1 and 3 B) Only 3 C) 3 and 4 D) 1, 2 and 4

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Answer & Solution

Answer: Option A

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24

The Sun appears red during Sunset

A) Reflection of light B) Scattering of light C) Refraction of light D) Diffraction of light

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Answer & Solution

Answer: Option B

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25

Which one of the following statements is correct about the magnification of an optical microscope?

A) Magnification increases with the increase in focal length of eyepiece B) Magnification increases with the increase in focal length of objective C) Magnification does not depend upon the focal length of eyepiece D) Magnification decreases with the increase in focal length of eyepiece

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Answer & Solution

Answer: Option D

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26

What is formula of mirror?

A) $$\frac{1}{f} + \frac{1}{u} = \frac{1}{v}$$ B) $$\frac{1}{f} + \frac{1}{v} = \frac{1}{u}$$ C) $$\frac{1}{u} + \frac{1}{v} = \frac{1}{f}$$ D) $$\frac{1}{u} - \frac{1}{v} = \frac{1}{f}$$

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Answer & Solution

Answer: Option C

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27

The phenomenon of light associated with the appearance of blue colour of the sky is

A) interference B) reflection C) refraction D) scattering

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Answer & Solution

Answer: Option D

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28

A plane glass slab is kept over coloured letters, the letter which appears least raised is

A) green B) violet C) red D) blue

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Answer & Solution

Answer: Option B

Solution:

When a plane glass slab is placed over coloured letters, the letters appear raised due to the phenomenon of refraction of light.

The apparent shift or raised appearance of the letters depends on the refractive index of the glass for different colours of light.

The refractive index (μ) of glass is not the same for all colours — it varies with wavelength due to dispersion of light.

Violet light has the shortest wavelength and is refracted the most, hence it has the highest refractive index in glass.

On the other hand, red light has the longest wavelength and is refracted the least, having the lowest refractive index.

The apparent depth (and hence the raised appearance) of the image is inversely proportional to the refractive index. Therefore, the greater the refractive index, the less raised the image appears.

Hence, among all colours, the violet letter appears the least raised because it has the maximum refractive index.

Therefore, the correct answer is Option B: violet.

29

. . . . . . . . helps the eye to adjust the focal length of the lens.

A) Lens B) Ciliary body C) Retina D) Entire eye ball

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Answer & Solution

Answer: Option B

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30

When a beam of white light is allowed to fall on a prism, the maximum deviation of the emerging light occurs for

A) red light B) violet light C) yellow light D) blue light

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Answer & Solution

Answer: Option B

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Light MCQ question and answer with solution | Physics Gk MCQs