Physics · Science General

Optics and Light Properties

2,019 Questions

Optics and light properties focus on the behavior of light, including reflection, refraction, dispersion, and polarization. This topic also covers the wave nature of light, illumination, and the functioning of optical instruments like microscopes. Questions on these concepts are common in general science sections of SSC, Railways, and State exams.

Reflection and mirrorsRefraction and mediumsLight wave theoriesPolarization and intensity

Optics and Light Properties Questions

Multiple choice physics refraction of light the nature of light speed of light and optical density introduction to light

Mark the correct statements (s) for a very thin soap film (RI = 1.33) whose thickness is much less then wavelength of visible light.

  1. Film appears dark.

  2. Film appears shiny.

  3. Film on glass (RI = 1.5) appears dark.

  4. Film on glass (RI = 1.5) appears shiny.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For a very thin film (t << lambda), the path difference is negligible. The phase change occurs at the reflection from the glass interface (n=1.5 > n=1.33), leading to destructive interference, making it appear dark.

Multiple choice physics refraction of light the nature of light speed of light and optical density introduction to light

When a ray of light enters glass from water, it bends :

  1. Away from the normal due to increase in the speed of light

  2. Away from the normal due to decrease in the speed of light

  3. Towards the normal due to decrease in the speed of light.

  4. Towards the normal due to increase in the speed of light.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When a ray of light enters from glass to water, it bends towards normal due to increase in speed of light. 

As we know,

          $\mu=\dfrac{c}{v}$

         $\mu$ for water is less than that of glass, as glass acts as a denser medium. $\therefore$ the speed of light in glass will be less than that in water.

Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

Metallic solids are always opaque because:

  1. they reflect all the incident light

  2. they scatter all the incident light

  3. the incident light is readily absorbed by the free electrons in a metal

  4. the energy band traps the incident
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Metals are opaque because they have metallic bonding which means that all of the atoms are surrounded by free-moving electrons.


The incident light on metals is absorbed by large numbers of available free electrons in metals to increase their kinetic energy and hence they are opaque.

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

Choose the correct answer from the alternatives given.
Radio waves diffract around building although light waves do not. The reason is that radio waves

  1. travel with speed larger than c

  2. have much larger wavelength than light

  3. are not electromagnetic waves

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$Answer:-$ B

Both radio and light waves are EM waves, just in different frequency ranges. The wavelength of visible light is typically around the 600 nm range, which is 6/1000 of a millimeter (very small!). Radio waves on the other hand, often wave wavelengths of a few yards long. For a wave to diffract around an object, the size of the object must be on the same order of the wavelength of the wave.

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

Choose the correct answer from alternatives given.
The phenomena involved in the reflection of radio waves by ionosphere is similar to

  1. reflection of light by a plane mirror.

  2. total internal reflection of light in air during a mirage.

  3. dispersion of light by water molecules during the formation of a rainbow.

  4. scattering of light by the particles of air.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The phenomenon involved in the reflection of radiowaves by ionosphere is similar to total internal reflection of light in air during a mirage (angle of incidence gt critical angle). It is same as the formation of the rainbow because it also involves the process of total internal reflection.


Choice $(b)$ is correct.

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

Fluorescent tubes give more light than a filament bulb of same power because

  1. the tube contains gas at low temperature

  2. ultraviolet light is converted into visible light by fluorescence

  3. light is diffused through the walls of the tube

  4. it produces more heat than bulb
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The tubelight has coating of fluorescent material which converts ultra violet light into visible light. Hence the light is more intense. 

Multiple choice physics electromagnetic waves properties and uses of different radiation electromagnetic spectrum spectrum

 Which one of waves tans our skin and causes some substances to become fluorescent?

  1. infrared waves.

  2. ultraviolet waves.

  3. gamma rays.

  4. infrared and ultraviolet waves both.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ultraviolet rays (or waves) tan our skin and cause some substances to become fluoroseun sun is important source of ultraviolet light. Sun rays reach our skin and burns the upper layer of skin, causing sunburns prolonged doses of UV radiation can induce skin cancer in human beings.

Ozone layer is protecting us from UV rays but the problem is that Ozone layer is also depleting because of excessive use of CFC's.

Multiple choice

What is the term for the technique of using a snoot to create a narrow, concentrated beam of light?

  1. Diffusion

  2. Spotlighting

  3. Backlighting

  4. Sidelighting
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Spotlighting is a lighting technique that uses a snoot to create a narrow, concentrated beam of light with a defined shape.

Multiple choice

What is the principle of spectrophotometry?

  1. The absorption of light by a sample is proportional to the concentration of the analyte.

  2. The emission of light by a sample is proportional to the concentration of the analyte.

  3. The scattering of light by a sample is proportional to the concentration of the analyte.

  4. The reflection of light by a sample is proportional to the concentration of the analyte.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The principle of spectrophotometry is that the absorption of light by a sample is proportional to the concentration of the analyte.

Multiple choice

What is the bending of light around massive objects called?

  1. Gravitational lensing

  2. Refraction

  3. Reflection

  4. Diffraction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gravitational lensing is the bending of light around massive objects, predicted by general relativity.

Multiple choice

What is the basic principle behind spectroscopy?

  1. The interaction of light with matter

  2. The emission of light by excited atoms

  3. The absorption of light by molecules

  4. The reflection of light from surfaces
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Spectroscopy is based on the interaction of light with matter, which can result in the absorption, emission, or scattering of light.