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 newton's colour disc light and the formation of shadows physics

The discovery of Newton's colour disc proves which of the following statement?

  1. Light is colourless

  2. Light is not colourless

  3. Light has only 1 colour

  4. Light has only 3 basic colours
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The perception of a picture or a color stays in the human brain for a fraction of a second. Newton's color disk is a mechanical device that rotates an array of colors arranged as petals or gradients around an axis and when the disc rotates fast enough the perception of the color changes to white. This is because white light is nothing but the mixture of light of all wavelengths in the visible range.

Sir Isaac Newton used this device to prove the above assertion that white color is the mixture of all colors.

SO Light is not colourless.

Multiple choice newton's colour disc light and the formation of shadows physics

When sun rays are passed through a glass prism it gets

  1. Deviated, but not dispersed

  2. Deviated and dispersed

  3. Dispersed, but not deviated

  4. Neither deviated nor dispersed
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When white light passes through a prism, it undergoes refraction (deviation) and splits into its component colors (dispersion) due to the different refractive indices of the wavelengths.

Multiple choice multiple-slit diffraction the principle of superposition of waves superposition of waves oscillations and waves physics

The amount of light that falls per unit area held perpendicular to the rays in one second is called

  1. Candle power

  2. Dioptre

  3. Lumen

  4. Intensity of illumination
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Candle power- It is the rating of light output at source. It is the the candle's luminous intensity in a particular direction.

Dioptre- It is the ability of a lens to bend the light rays. A unit of power of lens.
Lumen- The amount of energy emanating from one square meter of surface.
Intensity of illumination - The amount of light falling on per unit area, held perpendicular to the rays in one second.

Multiple choice

Which of the following properties of laser?

  1. Refraction

  2. Reflection

  3. Coherence

  4. Deflection
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Laser light is characterized by coherence, meaning the light waves are in phase with each other in both time and space. Refraction and reflection are general properties of light, not specific to lasers.

Multiple choice

Exposure to which light may accelerate aging?

  1. Blue light

  2. Red light

  3. Yellow light

  4. None of above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

High-energy visible (HEV) light, commonly known as blue light, has been shown to potentially contribute to skin aging and damage when exposure is prolonged.

Multiple choice physics option a: relativity the nature of light speed of light and optical density introduction to light

If the relative permeability of a medium is $ \mu _r$ and its dielectric constant is  $\varepsilon _r$ then the velocity of light in that medium will be

  1. $ \sqrt{\dfrac { \mu _r }{ { { \varepsilon } _{ r } } }} $
  2. $ \dfrac { 1 }{ \sqrt { { \mu } _{ r }{ \varepsilon } _{ r } } } $
  3. $ \sqrt { { \mu } _{ r }{ \varepsilon } _{ r }/{ \mu } _{ { \varepsilon } _{ 0 } } } $
  4. $ \sqrt { { \mu } _{ 0 }{ \varepsilon } _{ 0 }/{ \mu } _{ { r } }{ \varepsilon } _{ r } } $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$c=\dfrac{1}{\sqrt{\epsilon _0\mu _0}}$

$v=\dfrac{1}{\sqrt{\epsilon\mu}}=\dfrac{1}{\sqrt{\epsilon _0\epsilon _r\mu _0\mu _r}}$
$=\dfrac{c}{\sqrt{\epsilon _r\mu _r}}$

Multiple choice physics option a: relativity the nature of light speed of light and optical density introduction to light

For a medium with permitivity $\epsilon$ and permeability $\mu$, the velocity of light is given by:

  1. $\sqrt{\mu/\epsilon}$
  2. $\sqrt{\mu\epsilon}$
  3. $1/\sqrt{\mu\epsilon}$
  4. $\sqrt{\epsilon/\mu}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The velocity of electromagnetic radiation is the velocity of light (c), i.e., 

$c=\dfrac {1}{\sqrt{\mu\epsilon}}$
where $\mu$ is the permeability and $\epsilon$ is the permitivity

Multiple choice physics option a: relativity the nature of light speed of light and optical density introduction to light

If velocity of an electromagnetic wave in a medium is $3\times 10^8m/s$ then find refractive index of medium.

  1. $1$
  2. $2$
  3. $0.5$
  4. $0.25$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

We know that 
$\mu=\dfrac{V _{n}}{V _{m}}$

When $\mu=$ refractive index of wave
$V _{n}=$ velocity of wave in vacuum
$V _{m}=$ velocity of wave in medium
Now, velocity of wave in vacuum $=3\times 10^{8}m/s$
$\Rightarrow V _{n}=3\times 10^{8}m/s$
velocity of wave in medium $=3\times 10^{8}m/s$ (given)
$\Rightarrow V _{m}=3\times 10^{8}m/s$
Hence, $\mu=\dfrac{3\times 10^{8}}{3\times 10^{8}}=1$
$\Rightarrow \mu=1 =$ option $A$


Multiple choice physics option a: relativity the nature of light speed of light and optical density introduction to light

Three observers $A,B$ and $C$ measure the speed of light coming from a source as $v _A,v _B$ and $v _C$. Observer $A$ moves towards the source, $C$ moves away from source and $B$ stays stationary. The surrounding medium is water. If A and C are moving at the same speed, then

  1. $\displaystyle v _A>v _B>v _C$
  2. $\displaystyle v _A < v _B < v _C $
  3. $\displaystyle v _A=v _B=v _C$
  4. $\displaystyle v _B=\frac{1}{2}(v _C+v _A)$
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

Speed of the light is constant with respect to any observer holds only for the vacuum. In different medium (say water) if observer is moving with respect to medium towards the source, the speed observed by the observer will be more compared to a stationary observer. 
Same thing holds for a observer moving away from the source. Hence Option A. 
Since they are moving at the same speed, change in speed will be same and hence Option D. 
So answer is A and D.

Multiple choice physics option a: relativity the nature of light speed of light and optical density introduction to light

Which of the following properties of light conclusively support wave theory of light?

  1. Light obeys laws of reflection

  2. Speed of light in water is smaller than the speed in vacuum

  3. Light doesn't show interferrence

  4. Light shows photoelectric effect
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Laws of reflection was successfully explained by both wave theory and corpuscular theory of light.
Only Speed of light in water is smaller than the speed in vacuum was was proven by wave theory of light.
Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

In which form does the Light propagates?

  1. Electric waves

  2. Magnetic waves

  3. Electromagnetic waves

  4. Sound wave
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Electromagnetic waves are waves which can travel through the vacuum of outer space.light waves are examples of electromagnetic waves.
so,Light propagates in the form of electromagnetic waves.