Fiveable
Fiveable

or

Log in

Find what you need to study


Light

Find what you need to study

6.2 Electromagnetic Waves

5 min readdecember 30, 2022

S

Saarah Hasan

Daniella Garcia-Loos

Daniella Garcia-Loos

S

Saarah Hasan

Daniella Garcia-Loos

Daniella Garcia-Loos

6.2: Electromagnetic Waves

We briefly mentioned electromagnetic waves in 6.1, but let’s review them a little and get a bit more in-depth. Once again, what is an ?

An is a wave that’s capable of transmitting its energy through a vacuum; electromagnetic waves are produced by the vibrations of charged particles, don’t require a medium to travel, and are always transverse.

Some new stuff to dig into: electromagnetic waves are made up of electric and magnetic fields that oscillate perpendicular to each other. As shown in the image below, both fields are perpendicular to each other and perpendicular to their direction of motion as well.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-dsoSXuDf8Pv3.png?alt=media&token=7ec15043-dc19-47a7-b94d-031c535424f0

Taken from Wikimedia Commons

Another thing to remember: When electromagnetic waves travel through a vacuum, they all travel at a constant speed c, which equals 3*10^8m/s  (the speed of light).

v=λ*f becomes c=λ*f

Here are some key things to know about electromagnetic waves:

  • Electromagnetic waves are a type of energy that travels through space at the speed of light (approximately 299,792,458 m/s).
  • Electromagnetic waves are characterized by their frequency (measured in hertz) and wavelength (measured in meters).
  • Electromagnetic waves do not need a medium to travel through, unlike mechanical waves such as sound waves, which need a medium like air or water to propagate.
  • The electromagnetic spectrum is the range of all types of electromagnetic waves, from the longest wavelength (lowest frequency) to the shortest wavelength (highest frequency).
  • Examples of electromagnetic waves include radio waves, , , , , , and .
  • Electromagnetic waves have a wide range of applications, including communication, medicine, and imaging.

The Electromagnetic Spectrum

There’s a broad spectrum of wavelengths and frequencies that electromagnetic waves cover, and electromagnetic waves can be categorized by these two characteristics. The entire range of waves is called the electromagnetic (EM) spectrum. Types of waves on the EM spectrum include:

  • Radio waves
  • Infrared
  • Ultraviolet

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-Rr2ed9nl7ivd.png?alt=media&token=9ec7cec2-7154-4e7b-b417-4b37e6a23531

Taken from Wikimedia Commons

The narrow band of wavelengths that the human eye can see is the spectrum, whose colors in order of increasing wave frequency are red, orange, yellow, green, blue, and violet- remembered as . It’d be best to familiarize yourself with the names of the major categories of EM waves and .

Here are some key points about the electromagnetic spectrum:

  • The electromagnetic spectrum is the range of all types of electromagnetic waves, from the longest wavelength (lowest frequency) to the shortest wavelength (highest frequency).
  • The electromagnetic spectrum includes radio waves, , , , , , and .
  • Each type of has a different wavelength and frequency, and is associated with a different range of energy.
  • Radio waves have the longest wavelengths and lowest frequencies, and are used for communication and navigation.
  • have shorter wavelengths and higher frequencies, and are used for communication, radar, and cooking.
  • has shorter wavelengths and higher frequencies than , and is emitted by warm objects. It is used for thermal imaging and heating.
  • has even shorter wavelengths and higher frequencies, and is the part of the electromagnetic spectrum that is visible to the human eye. It is used for vision and lighting.
  • Ultraviolet radiation has shorter wavelengths and higher frequencies than , and is harmful to living tissue. It is used for sterilization and tanning.
  • have shorter wavelengths and higher frequencies than , and are used for medical imaging and cancer treatment.
  • have the shortest wavelengths and highest frequencies, and are emitted by radioactive materials and nuclear reactions. They are used for cancer treatment and imaging.

A Connection to Everyday Life

Electromagnetic waves to the left of the spectrum—UV rays, , —have high frequencies. Due to their high frequencies, these types of radiation have high energies, which can be detrimental to our health if precautions aren’t taken. That’s why we wear sunscreen whenever we go out and why lead shields are placed over parts of our body that aren’t being imaged whenever we get an X-ray.

Electromagnetic waves to the right of the spectrum—infrared rays, , radio waves—have low frequencies, so radiation from these types isn’t dangerous and doesn’t really affect our health.

Here are some key points about representations and models of electromagnetic waves:

  • One way to represent electromagnetic waves is with a , which shows the oscillating electric and magnetic fields of the wave as a function of time.
  • Another way to represent electromagnetic waves is with a model, which shows the oscillating electric and magnetic fields of the wave as a function of position.
  • In both of these representations, the is perpendicular to the , and the direction of the wave's propagation is perpendicular to both fields.
  • The frequency of an is related to the energy of the wave, with higher frequency waves having higher energy.
  • The of an is related to the intensity (or power) of the wave, with higher waves having higher intensity.
  • Electromagnetic waves can be transmitted through a vacuum because they are composed of oscillating electric and magnetic fields, which can interact with charged particles and exert forces on them. This interaction allows electromagnetic waves to transfer energy from one point to another without the need for a physical medium.
  • Practice Problems:

    1. In the electromagnetic spectrum, rank the following electromagnetic waves in terms of increasing wavelength.

    https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-LoMNqEHBlomL.png?alt=media&token=6135807e-560a-4718-9b5c-fdd3380f34f1

    https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-drYtAbR3sUd5.png?alt=media&token=8d7b8333-aa71-4c6d-b8b3-5c01892bc4fd

    2. For the five types of electromagnetic radiation listed above, which of the following correctly describes the way in which wavelength, frequency and speed, change as one goes from the left to right on the list?

    WavelengthFrequencySpeed
    ADecreasesDecreasedDecreases
    BDecreasesIncreasedRemains the Same
    CIncreasesDecreasesRemains the Same
    DIncreasesDecreasesIncreases
    EIncreasedIncreasesIncreases


    Answers:

    1. E: λ changes the opposite of frequencies (high freq = low λ) … based on this and knowledge of the EM spectrum, the answer is E.

    2. B: Known facts about the EM spectrum.

    Key Terms to Review (16)

    Amplitude

    : Amplitude refers to the maximum displacement or distance from equilibrium position that a particle in a wave moves. It represents the energy carried by the wave.

    Electric field

    : An electric field refers to an invisible area surrounding an electrically charged object or particle, where other charged objects experience either attraction or repulsion forces.

    Electromagnetic wave

    : An electromagnetic wave is a type of wave that consists of oscillating electric and magnetic fields, which travel through space at the speed of light.

    Frequency (f)

    : Frequency refers to the number of complete cycles or oscillations per unit time. In physics, it specifically refers to the number of wave crests passing through a given point per second.

    Gamma rays

    : Gamma rays are high-energy electromagnetic waves that are emitted from the nucleus of an atom during radioactive decay.

    Infrared radiation

    : Infrared radiation refers to electromagnetic waves with longer wavelengths than those of visible light but shorter than microwaves. It is associated with heat energy and is often used in devices like remote controls and thermal cameras.

    Magnetic field

    : A magnetic field is a region in space where a magnetic force can be detected. It is created by moving electric charges or by magnets.

    Microwaves

    : Microwaves are a type of electromagnetic radiation with longer wavelengths than those of visible light. They are commonly used in microwave ovens to heat food.

    ROYGBV

    : ROYGBV is an acronym that represents the colors of the visible light spectrum in order: Red, Orange, Yellow, Green, Blue, and Violet.

    Sine Wave

    : A sine wave is a smooth repetitive oscillation that can be represented by a mathematical function called sine. It has a characteristic shape resembling gentle hills and valleys.

    Speed of light (c)

    : The speed of light is the fastest possible speed at which energy or information can travel in a vacuum. It is approximately 299,792,458 meters per second.

    Transverse wave

    : A transverse wave is a type of wave in which particles vibrate perpendicular to the direction in which the wave travels.

    Ultraviolet radiation

    : Ultraviolet radiation refers to a type of electromagnetic radiation that has a shorter wavelength and higher energy than visible light. It is commonly found in sunlight and can cause sunburns and skin damage.

    Visible light

    : Visible light is the portion of the electromagnetic spectrum that can be detected by the human eye. It consists of different colors with varying wavelengths, ranging from red to violet.

    Wavelength (λ)

    : Wavelength refers to the distance between two consecutive points on a wave that are in phase with each other. It is usually measured from crest to crest or trough to trough.

    X-rays

    : X-rays are a form of high-energy electromagnetic waves that have shorter wavelengths than ultraviolet rays but longer wavelengths than gamma rays. They are commonly used in medical imaging to visualize bones and internal structures.

    6.2 Electromagnetic Waves

    5 min readdecember 30, 2022

    S

    Saarah Hasan

    Daniella Garcia-Loos

    Daniella Garcia-Loos

    S

    Saarah Hasan

    Daniella Garcia-Loos

    Daniella Garcia-Loos

    6.2: Electromagnetic Waves

    We briefly mentioned electromagnetic waves in 6.1, but let’s review them a little and get a bit more in-depth. Once again, what is an ?

    An is a wave that’s capable of transmitting its energy through a vacuum; electromagnetic waves are produced by the vibrations of charged particles, don’t require a medium to travel, and are always transverse.

    Some new stuff to dig into: electromagnetic waves are made up of electric and magnetic fields that oscillate perpendicular to each other. As shown in the image below, both fields are perpendicular to each other and perpendicular to their direction of motion as well.

    https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-dsoSXuDf8Pv3.png?alt=media&token=7ec15043-dc19-47a7-b94d-031c535424f0

    Taken from Wikimedia Commons

    Another thing to remember: When electromagnetic waves travel through a vacuum, they all travel at a constant speed c, which equals 3*10^8m/s  (the speed of light).

    v=λ*f becomes c=λ*f

    Here are some key things to know about electromagnetic waves:

    • Electromagnetic waves are a type of energy that travels through space at the speed of light (approximately 299,792,458 m/s).
    • Electromagnetic waves are characterized by their frequency (measured in hertz) and wavelength (measured in meters).
    • Electromagnetic waves do not need a medium to travel through, unlike mechanical waves such as sound waves, which need a medium like air or water to propagate.
    • The electromagnetic spectrum is the range of all types of electromagnetic waves, from the longest wavelength (lowest frequency) to the shortest wavelength (highest frequency).
    • Examples of electromagnetic waves include radio waves, , , , , , and .
    • Electromagnetic waves have a wide range of applications, including communication, medicine, and imaging.

    The Electromagnetic Spectrum

    There’s a broad spectrum of wavelengths and frequencies that electromagnetic waves cover, and electromagnetic waves can be categorized by these two characteristics. The entire range of waves is called the electromagnetic (EM) spectrum. Types of waves on the EM spectrum include:

    • Radio waves
    • Infrared
    • Ultraviolet

    https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-Rr2ed9nl7ivd.png?alt=media&token=9ec7cec2-7154-4e7b-b417-4b37e6a23531

    Taken from Wikimedia Commons

    The narrow band of wavelengths that the human eye can see is the spectrum, whose colors in order of increasing wave frequency are red, orange, yellow, green, blue, and violet- remembered as . It’d be best to familiarize yourself with the names of the major categories of EM waves and .

    Here are some key points about the electromagnetic spectrum:

    • The electromagnetic spectrum is the range of all types of electromagnetic waves, from the longest wavelength (lowest frequency) to the shortest wavelength (highest frequency).
    • The electromagnetic spectrum includes radio waves, , , , , , and .
    • Each type of has a different wavelength and frequency, and is associated with a different range of energy.
    • Radio waves have the longest wavelengths and lowest frequencies, and are used for communication and navigation.
    • have shorter wavelengths and higher frequencies, and are used for communication, radar, and cooking.
    • has shorter wavelengths and higher frequencies than , and is emitted by warm objects. It is used for thermal imaging and heating.
    • has even shorter wavelengths and higher frequencies, and is the part of the electromagnetic spectrum that is visible to the human eye. It is used for vision and lighting.
    • Ultraviolet radiation has shorter wavelengths and higher frequencies than , and is harmful to living tissue. It is used for sterilization and tanning.
    • have shorter wavelengths and higher frequencies than , and are used for medical imaging and cancer treatment.
    • have the shortest wavelengths and highest frequencies, and are emitted by radioactive materials and nuclear reactions. They are used for cancer treatment and imaging.

    A Connection to Everyday Life

    Electromagnetic waves to the left of the spectrum—UV rays, , —have high frequencies. Due to their high frequencies, these types of radiation have high energies, which can be detrimental to our health if precautions aren’t taken. That’s why we wear sunscreen whenever we go out and why lead shields are placed over parts of our body that aren’t being imaged whenever we get an X-ray.

    Electromagnetic waves to the right of the spectrum—infrared rays, , radio waves—have low frequencies, so radiation from these types isn’t dangerous and doesn’t really affect our health.

    Here are some key points about representations and models of electromagnetic waves:

  • One way to represent electromagnetic waves is with a , which shows the oscillating electric and magnetic fields of the wave as a function of time.
  • Another way to represent electromagnetic waves is with a model, which shows the oscillating electric and magnetic fields of the wave as a function of position.
  • In both of these representations, the is perpendicular to the , and the direction of the wave's propagation is perpendicular to both fields.
  • The frequency of an is related to the energy of the wave, with higher frequency waves having higher energy.
  • The of an is related to the intensity (or power) of the wave, with higher waves having higher intensity.
  • Electromagnetic waves can be transmitted through a vacuum because they are composed of oscillating electric and magnetic fields, which can interact with charged particles and exert forces on them. This interaction allows electromagnetic waves to transfer energy from one point to another without the need for a physical medium.
  • Practice Problems:

    1. In the electromagnetic spectrum, rank the following electromagnetic waves in terms of increasing wavelength.

    https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-LoMNqEHBlomL.png?alt=media&token=6135807e-560a-4718-9b5c-fdd3380f34f1

    https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-drYtAbR3sUd5.png?alt=media&token=8d7b8333-aa71-4c6d-b8b3-5c01892bc4fd

    2. For the five types of electromagnetic radiation listed above, which of the following correctly describes the way in which wavelength, frequency and speed, change as one goes from the left to right on the list?

    WavelengthFrequencySpeed
    ADecreasesDecreasedDecreases
    BDecreasesIncreasedRemains the Same
    CIncreasesDecreasesRemains the Same
    DIncreasesDecreasesIncreases
    EIncreasedIncreasesIncreases


    Answers:

    1. E: λ changes the opposite of frequencies (high freq = low λ) … based on this and knowledge of the EM spectrum, the answer is E.

    2. B: Known facts about the EM spectrum.

    Key Terms to Review (16)

    Amplitude

    : Amplitude refers to the maximum displacement or distance from equilibrium position that a particle in a wave moves. It represents the energy carried by the wave.

    Electric field

    : An electric field refers to an invisible area surrounding an electrically charged object or particle, where other charged objects experience either attraction or repulsion forces.

    Electromagnetic wave

    : An electromagnetic wave is a type of wave that consists of oscillating electric and magnetic fields, which travel through space at the speed of light.

    Frequency (f)

    : Frequency refers to the number of complete cycles or oscillations per unit time. In physics, it specifically refers to the number of wave crests passing through a given point per second.

    Gamma rays

    : Gamma rays are high-energy electromagnetic waves that are emitted from the nucleus of an atom during radioactive decay.

    Infrared radiation

    : Infrared radiation refers to electromagnetic waves with longer wavelengths than those of visible light but shorter than microwaves. It is associated with heat energy and is often used in devices like remote controls and thermal cameras.

    Magnetic field

    : A magnetic field is a region in space where a magnetic force can be detected. It is created by moving electric charges or by magnets.

    Microwaves

    : Microwaves are a type of electromagnetic radiation with longer wavelengths than those of visible light. They are commonly used in microwave ovens to heat food.

    ROYGBV

    : ROYGBV is an acronym that represents the colors of the visible light spectrum in order: Red, Orange, Yellow, Green, Blue, and Violet.

    Sine Wave

    : A sine wave is a smooth repetitive oscillation that can be represented by a mathematical function called sine. It has a characteristic shape resembling gentle hills and valleys.

    Speed of light (c)

    : The speed of light is the fastest possible speed at which energy or information can travel in a vacuum. It is approximately 299,792,458 meters per second.

    Transverse wave

    : A transverse wave is a type of wave in which particles vibrate perpendicular to the direction in which the wave travels.

    Ultraviolet radiation

    : Ultraviolet radiation refers to a type of electromagnetic radiation that has a shorter wavelength and higher energy than visible light. It is commonly found in sunlight and can cause sunburns and skin damage.

    Visible light

    : Visible light is the portion of the electromagnetic spectrum that can be detected by the human eye. It consists of different colors with varying wavelengths, ranging from red to violet.

    Wavelength (λ)

    : Wavelength refers to the distance between two consecutive points on a wave that are in phase with each other. It is usually measured from crest to crest or trough to trough.

    X-rays

    : X-rays are a form of high-energy electromagnetic waves that have shorter wavelengths than ultraviolet rays but longer wavelengths than gamma rays. They are commonly used in medical imaging to visualize bones and internal structures.


    © 2024 Fiveable Inc. All rights reserved.

    AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.


    © 2024 Fiveable Inc. All rights reserved.

    AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.