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  • List three “rules of thumb” that apply to the different frequencies along the electromagnetic spectrum.
  • Explain why the higher the frequency, the shorter the wavelength of an electromagnetic wave.
  • Draw a simplified electromagnetic spectrum, indicating the relative positions, frequencies, and spacing of the different types of radiation bands.
  • List and explain the different methods by which electromagnetic waves are produced across the spectrum.

In this module we examine how electromagnetic waves are classified into categories such as radio, infrared, ultraviolet, and so on, so that we can understand some of their similarities as well as some of their differences. We will also find that there are many connections with previously discussed topics, such as wavelength and resonance. A brief overview of the production and utilization of electromagnetic waves is found in [link] .

Electromagnetic waves
Type of EM wave Production Applications Life sciences aspect Issues
Radio&TV Accelerating charges Communications Remote controls MRI Requires controls for band use
Microwaves Accelerating charges&thermal agitation Communications Ovens Radar Deep heating Cell phone use
Infrared Thermal agitations&electronic transitions Thermal imaging Heating Absorbed by atmosphere Greenhouse effect
Visible light Thermal agitations&electronic transitions All pervasive Photosynthesis Human vision
Ultraviolet Thermal agitations&electronic transitions Sterilization Cancer control Vitamin D production Ozone depletion Cancer causing
X-rays Inner electronic transitions and fast collisions Medical Security Medical diagnosis Cancer therapy Cancer causing
Gamma rays Nuclear decay Nuclear medicineSecurity Medical diagnosis Cancer therapy Cancer causing Radiation damage

Connections: waves

There are many types of waves, such as water waves and even earthquakes. Among the many shared attributes of waves are propagation speed, frequency, and wavelength. These are always related by the expression v W = size 12{v rSub { size 8{W} } =fλ} {} . This module concentrates on EM waves, but other modules contain examples of all of these characteristics for sound waves and submicroscopic particles.

As noted before, an electromagnetic wave has a frequency and a wavelength associated with it and travels at the speed of light, or c size 12{c} {} . The relationship among these wave characteristics can be described by v W = size 12{v rSub { size 8{W} } =fλ} {} , where v W size 12{v rSub { size 8{W} } } {} is the propagation speed of the wave, f size 12{f} {} is the frequency, and λ size 12{λ} {} is the wavelength. Here v W = c size 12{v rSub { size 8{W} } =c} {} , so that for all electromagnetic waves,

c = . size 12{c = fλ} {}

Thus, for all electromagnetic waves, the greater the frequency, the smaller the wavelength.

[link] shows how the various types of electromagnetic waves are categorized according to their wavelengths and frequencies—that is, it shows the electromagnetic spectrum. Many of the characteristics of the various types of electromagnetic waves are related to their frequencies and wavelengths, as we shall see.

An electromagnetic spectrum is shown. Different wave category regions are indicated using double sided arrows based on the values of their wavelength, energy, and frequency; the visual strip is also shown. The radio wave region is further segmented into AM radio, FM radio, and microwaves bands.
The electromagnetic spectrum, showing the major categories of electromagnetic waves. The range of frequencies and wavelengths is remarkable. The dividing line between some categories is distinct, whereas other categories overlap.

Questions & Answers

how many subject is in physics
Adeshina Reply
the write question should be " How many Topics are in O- Level Physics, or other branches of physics.
how many topic are in physics
yh I need someone to explain something im tryna solve . I'll send the question if u down for it
Tamdy Reply
a ripple tank experiment a vibrating plane is used to generate wrinkles in the water .if the distance between two successive point is 3.5cm and the wave travel a distance of 31.5cm find the frequency of the vibration
the range of objects and phenomena studied in physics is
Bethel Reply
what is Linear motion
Hamza Reply
straight line motion is called linear motion
then what
linear motion is a motion in a line, be it in a straight line or in a non straight line. It is the rate of change of distance.
your are wrong Saeedul
Linear motion is a one-dimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimension
is a one-dimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimensions. 
what is a classical electrodynamics?
what is dynamics
dynamic is the force that stimulates change or progress within the system or process
what is the formula to calculate wavelength of the incident light
David Reply
if a spring is is stiffness of 950nm-1 what work will be done in extending the spring by 60mmp
Hassan Reply
State the forms of energy
Samzy Reply
Word : Mechanical wave Definition : The waves, which need a material medium for their propagation, e.g., Sound waves. \n\nOther Definition: The waves, which need a material medium for their propagation, are called mechanical waves. Mechanical waves are also called elastic waves. Sound waves, water waves are examples of mechanical waves.t Definition: wave consisting of periodic motion of matter; e.g. sound wave or water wave as opposed to electromagnetic wave.h
Clement Reply
what is mechanical wave
Akinpelu Reply
a wave which require material medium for its propagation
The S.I unit for power is what?
Samuel Reply
Am I correct
it can be in kilowatt, megawatt and so
OK that's right
SI.unit of power is.watt=j/c.but kw.and Mw are bigger.umots
What is physics
aish Reply
study of matter and its nature
The word physics comes from a Greek word Physicos which means Nature.The Knowledge of Nature. It is branch of science which deals with the matter and energy and interaction between them.
why in circular motion, a tangential acceleration can change the magnitude of the velocity but not its direction
Syafiqah Reply
because it is balanced by the inward acceleration otherwise known as centripetal acceleration
What is a wave
Mutuma Reply
Tramsmission of energy through a media
is the disturbance that carry materials as propagation from one medium to another
mistakes thanks
find the triple product of (A*B).C given that A =i + 4j, B=2i - 3j and C = i + k
Favour Reply
Difference between north seeking pole and south seeking pole
Stanley Reply

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Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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