Tag: the nature of light

Questions Related to the nature of light

The velocity of electromagnetic radiation in a medium of permittivity ${\varepsilon} _{0}$ and permeability ${\mu} _{0}$ is given by :

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

  1. $\sqrt { \dfrac { { \varepsilon } _{ 0 } }{ { \mu } _{ 0 } } } $

  2. $\sqrt { { \mu } _{ 0 }{ \varepsilon } _{ 0 } } $

  3. $\dfrac { 1 }{ \sqrt { { \mu } _{ 0 }{ \varepsilon } _{ 0 } } } $

  4. $\sqrt { \dfrac { { \mu } _{ 0 } }{ { \varepsilon } _{ 0 } } } $

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Correct Option: C
Explanation:

Velocity of electromagnetic radiation is the velocity of light $\left(c\right)$, i.e.,
$c=\dfrac { 1 }{ \sqrt { { \mu  } _{ 0 }{ \varepsilon  } _{ 0 } }  } $
where ${ \mu  } _{ 0 }$ is the permeability and ${ \varepsilon  } _{ 0 }$ is the permittivity of free space.

A certain color of light towards the purple end of the visible spectrum has a wavelength of $420\ nm$ in a vacuum.
What is the frequency of this light?
The speed of light in a vacuum is $3.00\times 10^8 m/s$

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

  1. $126 Hz$

  2. $1.26\times 10^{11}Hz$

  3. $7.1\times 10^{14}Hz$

  4. $1.4\times 10^{-15}Hz$

  5. $1.4\times 10^{-6}Hz$

Show answer
Correct Option: C
Explanation:

Given :   $v = 3.00 \times 10^8$  m/s                 $\lambda = 420$ nm $ = 420 \times 10^{-9}$  m

$\therefore$ Frequency of the light       $\nu = \dfrac{v}{\lambda} = \dfrac{3.00 \times 10^8}{420 \times 10^{-9}} = 7.1 \times 10^{14}$  $Hz$

Fill the blank space with the best suitable option. All electromagnetic waves have the same _________ while travelling in a vacuum.

physics electromagnetic waves and communication system maxwell's equations the nature of light introduction to electromagnetic waves

  1. amplitude

  2. frequency

  3. wavelength

  4. Intensity

  5. speed

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Correct Option: E
Explanation:

All electromagnetic waves (EM waves) travel with the speed of light in vacuum but these have different frequency, amplitude, wavelength and intensity.

Thus option E is correct.

This question has statement-1 and statement-2. Of the four choices given after the Statements, choose the one that best describes the two statements.
Statement 1: Short wave transmission is achieved due to the total internal reflection of the e-m wave from an appropriate height in the ionosphere.
Statement 2: Refractive index of a plasma is independent of the frequency of e-m waves.

physics electromagnetic waves and communication system maxwell's equations the nature of light introduction to electromagnetic waves

  1. Statement 1 is true, Statement 2 false.

  2. Statement 1 is false, Statement 2 is true

  3. Statement 1 is true, Statement 2 is true but statement 2 is not the correct of statement 1.

  4. Statement 1 is true, statement 2 is true and statement 2 is the correct explanation of statement 1.

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Correct Option: C

The waves which can not travel in vacuum are :

physics observing space: telescopes maxwell's equations the nature of light introduction to electromagnetic waves

  1. X-rays

  2. radio-waves

  3. infrasonic waves

  4. ultra-viloet rays

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Correct Option: C

Light can pass through

physics observing space: telescopes maxwell's equations the nature of light introduction to electromagnetic waves

  1. Vacuum

  2. Glass

  3. Air

  4. All of the above

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Correct Option: D
Explanation:

Light can pass through vacuum,glass and air.

Identify the electromagnetic wave which is most often used in medicine for diagnostic imaging?

physics observing space: telescopes maxwell's equations the nature of light introduction to electromagnetic waves

  1. infrared

  2. ultraviolet

  3. microwave

  4. radio

  5. gamma ray

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Correct Option: A
Explanation:

During diagnosis of the body heat signatures of the organs are vital. These heat waves lie in the infrared region of the spectrum.

Therefore, infrared waves are used in diagnostic imaging.

 Option A is, therefore, correct. 

Which of the following is responsible for passing the energy from one to the another to transmit the light waves.

physics observing space: telescopes maxwell's equations the nature of light introduction to electromagnetic waves

  1. atom

  2. neutron

  3. fiber

  4. object

  5. wavelength

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Correct Option: A
Explanation:

Answer A is correct 

Atom is responsible for transmission of light.
By collision of atoms they passes energy from one to another and hence light is transmitted. 

Identify the medium required for Electromagnetic waves to travel?

physics observing space: telescopes maxwell's equations the nature of light introduction to electromagnetic waves

  1. none

  2. liquid

  3. solid

  4. gas

  5. fluid (liquid or gas)

Show answer
Correct Option: A
Explanation:

Electromagnetic wave does not require any material medium to propagate. These can also travel through vacuum. Also EM waves travel with the speed equal to that of light  i.e $3 \times 10^8$ m/s

Identify which of the following best describe the difference between electromagnetic (EM) waves and other types of waves?

physics observing space: telescopes maxwell's equations the nature of light introduction to electromagnetic waves

  1. EM waves can travel without a medium.

  2. EM waves are higher in frequency than all other waves

  3. EM waves have shorter wave lengths than any other type of wave.

  4. EM waves transport matter and energy.

  5. EM waves require a medium to travel.

Show answer
Correct Option: A
Explanation:

EM waves do not require a material medium to travel, these can propagate even through vacuum while all other waves require a certain medium to travel.