Tag: introduction to electromagnetic waves

Quizzes (0) Questions (49)

Questions Related to introduction to electromagnetic waves

Multiple choice physics option a: relativity maxwell's equations the nature of light introduction to electromagnetic waves

According to Maxwell's hypothesis, changing of electric filed give rise to

  1. magnetic field

  2. pressure gradient

  3. charge

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

According to Maxwell's hypothesis, changing of electric field gives rise to Magnetic field.

We know that $F=qE,$, where $F$ is force and $E$ is electric field.
We can relate magnetic field and force by $F=qvB$, where $v$ is velocity and $B$ is the magnetic field.
Therefore we can obtain magnetic field by changing electric field.
Therefore option $A$ is correct.

Multiple choice physics option a: relativity maxwell's equations the nature of light introduction to electromagnetic waves

Unpolarized light falls first on polarizer $\left( P \right) $ and then on analyzer $\left( A \right) $. If the intensity of the transmitted light from the analyser is $\dfrac { 1 }{ 8 }$th of the incident unpolarized light. What will be the angle between optic axes of $P$ and $A$?

  1. ${ 45 }^{ o }$
  2. ${ 30 }^{ o }$

  3. Zero
  4. ${ 60 }^{ o }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given,
$I=\dfrac { { I } _{ 0 } }{ 2 } $              ....(i)
${ I }^{ ' }=I\cos ^{ 2 }{ \theta  } $                 $\left( \because { I }^{ ' }=\dfrac { { I } _{ 0 } }{ 8 }  \right) $
$\therefore \dfrac { { I } _{ 0 } }{ 8 } =\dfrac { { I } _{ 0 } }{ 2 } \cos ^{ 2 }{ \theta  } $
From the equation (i), we have
$\dfrac { 1 }{ 4 } =\cos ^{ 2 }{ \theta  } \Rightarrow \cos { \theta  } ={ 1 }/{ 2 }$
$\Rightarrow \cos { \theta  } =\cos { { 60 }^{ o } } $
$\Rightarrow \theta ={ 60 }^{ o }$

Multiple choice physics option a: relativity maxwell's equations the nature of light introduction to electromagnetic waves

A plane electromagnetic wave with an intensity of $200 W/m^2$ is incident normal to a flat plate of radius 30 cm. If the plate absorbs $60%$ and reflect $40%$ of the incident radiation, what is the momentum transferred to it in 5 min?

  1. $1.7 \times 10^{-3} kg ms^{-1}$
  2. $2.7 \times 10^{-4} kg ms^{-1}$
  3. $3.7 \times 10^{-4} kg ms^{-1}$
  4. $3.7 \times 10^{-3} kg ms^{-1}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice physics electromagnetic waves and communication system maxwell's equations the nature of light introduction to electromagnetic waves

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

  1. amplitude

  2. frequency

  3. wavelength

  4. Intensity

  5. speed
Reveal answer Fill a bubble to check yourself
E Correct answer
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.

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

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.

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

Statement 1 is true because the ionosphere reflects radio waves, enabling long-distance communication. Statement 2 is also true because the refractive index of plasma depends on the electron density and the frequency of the wave, but the statement as written is a common physics textbook fact that the refractive index varies with frequency, making the statement 'independent' false. However, given the options, the question implies both are true but unrelated.

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

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

  1. infrared

  2. ultraviolet

  3. microwave

  4. radio

  5. gamma ray
Reveal answer Fill a bubble to check yourself
A Correct answer
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. 

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

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

  1. atom

  2. neutron

  3. fiber

  4. object

  5. wavelength
Reveal answer Fill a bubble to check yourself
A Correct answer
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. 

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

Identify the medium required for Electromagnetic waves to travel?

  1. none

  2. liquid

  3. solid

  4. gas

  5. fluid (liquid or gas)
Reveal answer Fill a bubble to check yourself
A Correct answer
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