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6 Electromagnetic Waves Online Quiz Questions

Use this free practice quiz with 20 questions to review 6 Electromagnetic Waves, test your knowledge, and prepare for your next test or exam.

20 questions
01
True or false
1 point

True or false: Electromagnetic waves can propagate through a region containing no material medium.

  1. A

    True

  2. B

    False

02
Choose all
1 point

Select all the options that are forms of electromagnetic radiation.

  1. A

    Radio waves

  2. B

    Sound waves

  3. C

    Microwaves

  4. D

    Visible light

03
Written response
1 point

What behavior of electric charges can generate electromagnetic waves? Enter a concise phrase.

04
Choose all
1 point

Select all statements that correctly describe the geometric domains of the integral forms of Maxwell’s equations.

  1. A

    Gauss’s law and Gauss’s law for magnetism apply to closed surfaces.

  2. B

    Faraday’s law applies to a closed surface.

  3. C

    Faraday’s law and the Ampère–Maxwell law apply around closed loops.

  4. D

    All four integral equations apply around closed loops.

05
Fill in the blank
1 point

According to Maxwell’s addition to Ampère’s law, a changing electric field can produce a even where no conduction current flows.

06
True or false
1 point

True or false: In a plane electromagnetic wave, the electric and magnetic contributions to the energy density are equal.

  1. A

    True

  2. B

    False

07
Fill in the blank
1 point

For a plane electromagnetic wave in vacuum, the field amplitudes satisfy E0=E_0=.

08
Choose one
1 point

A plane electromagnetic wave has its electric field along +x+x and its magnetic field along +y+y. In which direction does the wave travel?

  1. A

    The +x+x direction

  2. B

    The +y+y direction

  3. C

    The +z+z direction

  4. D

    The −z-z direction

09
Written response
1 point

A sinusoidal electromagnetic wave’s field amplitude is doubled while other conditions remain unchanged. By what factor does its average intensity change?

10
Choose one
1 point

A wave in vacuum has frequency 6.00×1014 Hz6.00\times10^{14}\ \text{Hz}. Using c=3.00×108 m/sc=3.00\times10^8\ \text{m/s} and c=fλc=f\lambda, what is its wavelength?

  1. A

    5.00×10−8 m5.00\times10^{-8}\ \text{m}

  2. B

    5.00×10−7 m5.00\times10^{-7}\ \text{m}

  3. C

    2.00×10−6 m2.00\times10^{-6}\ \text{m}

  4. D

    1.80×1023 m1.80\times10^{23}\ \text{m}

11
Choose one
1 point

Under what condition do Maxwell’s equations predict the electromagnetic field wave equations described for vacuum?

  1. A

    A region with a steady conduction current but no changing fields

  2. B

    A region with no charge or current

  3. C

    A region containing charge but no electric field

  4. D

    Any material region, regardless of its charges or currents

12
Choose one
1 point

A sinusoidal wave in vacuum has intensity 100 W/m2100\ \text{W/m}^2. Estimate its electric-field amplitude using E0=2I/(ε0c)E_0=\sqrt{2I/(\varepsilon_0c)}, with ε0=8.85×10−12\varepsilon_0=8.85\times10^{-12} and c=3.00×108c=3.00\times10^8 in SI units.

  1. A

    275 V/m275\ \text{V/m}

  2. B

    9.2×10−7 V/m9.2\times10^{-7}\ \text{V/m}

  3. C

    100 V/m100\ \text{V/m}

  4. D

    3.00×108 V/m3.00\times10^8\ \text{V/m}

13
Open ended
1 point

Explain the physical meaning of Poynting’s theorem, ∂u∂t+∇⋅S=−J⋅E\frac{\partial u}{\partial t}+\nabla\cdot\mathbf{S}=-\mathbf{J}\cdot\mathbf{E}. In particular, describe how field energy in a region can change and what J⋅E\mathbf{J}\cdot\mathbf{E} represents.

14
True or false
1 point

True or false: Electromagnetic waves can travel through a vacuum without a material medium.

  1. A

    True

  2. B

    False

15
Choose one
1 point

Which pair of Maxwell’s equations is written as an integral over a closed surface?

  1. A

    Faraday’s law and the Ampère–Maxwell law

  2. B

    Gauss’s law and Gauss’s law for magnetism

  3. C

    Gauss’s law and Faraday’s law

  4. D

    All four equations

16
Written response
1 point

What is the name of the law stating that a changing magnetic field produces an electric field?

17
Choose one
1 point

Which situation can generate electromagnetic waves?

  1. A

    A stationary charge held at rest

  2. B

    A steady current in a wire that does not change

  3. C

    An accelerating charge, such as an oscillating electron

  4. D

    A magnetic field that remains constant

18
Choose one
1 point

A plane electromagnetic wave has its electric field directed along +y+y and its magnetic field along +z+z. In which direction does the wave travel?

  1. A

    +x+x

  2. B

    −x-x

  3. C

    +y+y

  4. D

    −z-z

19
Choose one
1 point

A plane electromagnetic wave travels through vacuum. How do its electric and magnetic contributions to the energy density compare?

  1. A

    The electric contribution is always greater than the magnetic contribution.

  2. B

    The electric and magnetic contributions are equal.

  3. C

    The magnetic contribution is always greater than the electric contribution.

  4. D

    Only the electric field contributes to the energy density.

20
Written response
1 point

A wave travels in vacuum with wavelength 2.00 m2.00\ \text{m}. Using c=3.00×108 m/sc=3.00\times10^8\ \text{m/s} and c=fλc=f\lambda, calculate its frequency.