Tag: the nature of electromagnetic waves

Quizzes (0) Questions (30)

Questions Related to the nature of electromagnetic waves

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

The waves that are propagated by simultaneous periodic variations of electric and magnetic field intensity known as:

  1. Transverse wave

  2. Longitudinal wave

  3. Electromagnetic wave

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

Maxwell predicted that an accelerated charge produces a sinusoidal time varying magnetic field, which in turn produces a sinusoidal time varying electric field. These two fields are mutually perpendicular to each other and sources of each other. They (fields) form an electromagnetic wave i.e. the wave that is propagated by simultaneous periodic variations of electric field and magnetic field intensity.

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

Select wrong statement from the following:
Electromagnetic waves

  1. are transverse

  2. travel with same speed in all media

  3. travel with the speed of light

  4. are produced by accelerating charge
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Electromagnetic waves are transverse and do not need a material medium to travel. 
The speed of all electromagnetic waves is equal to the speed of light. In fact this let to the conclusion that light is an electromagnetic wave.

Accelerating charge particles produce electromagnetic waves.
However the speed of electromagnetic waves changes with media as 
$v=\dfrac{c}{n}$
where n is the refractive index of the given medium.

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

The wavelengths for the light of red and blue colours are roughly $7.8\times 10^{-7}m$ and $4.8\times 10^{-7}m$ respectively. Which colour has the greater speed in glass?

  1. Red light

  2. Violet light

  3. Yellow light

  4. All colors have same speed
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When travelling through a medium, the frequency of light doesn't change. Hence, red light having the maximum wavelength will travel fastest through glass as speed of light is given by $v=f\lambda$ where; $f$ is the frequency and $\lambda$ is the wavelength of light travelling at speed $v$.

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

What is the speed of Light $c$?

  1. $c=3\times 10^{-8} m s^{-1}$

  2. $c=3\times 10^8 km s^{-1}$

  3. $c=3\times 10^8 mm s^{-1}$

  4. $c=3\times 10^8 m s^{-1}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its value is exactly $299792458$ meters per second.
That is, $c=3\times { 10 }^{ 8 }m/s$.

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.

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

As speed decreases, if we change medium of electromagnetic waves from air to water, frequency

  1. also decreases.

  2. also increases.

  3. remains same.

  4. may increase or decrease.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

As speed decreases, if change medium of electromagnetic wave from air to water, frequency remains same.

As we go from one medium to another the frequency stays same, but the wavelength changes. Change in speed is proportional to change in wavelength.

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

A plane electromagnetic wave of angular frequency ${ mm }^{ 2 }$ propagates in a poorly conducting medium of conductivity $\sigma $ and relative permittivity $\epsilon $ Find the ratio of conduction current density and displacement current density in the medium.

  1. ${ \epsilon \epsilon } _{ 0 }\omega /\sigma $

  2. $\sigma /{ \epsilon \epsilon } _{ \sigma }\omega $

  3. $\omega /{ \sigma \epsilon } _{ 0 }\omega $

  4. $\omega \sigma /{ \epsilon } _{ 0 }\epsilon $
Reveal answer Fill a bubble to check yourself
A Correct answer