<< Chapter < Page Chapter >> Page >

Electromagnetic spectrum

The electromagnetic spectrum as a function of frequency. The different types according to wavelength are shown as well as everyday comparisons.

Electromagnetic radiation allows us to observe the world around us. Some materials and objects emit electromagnetic radiation and some reflect the electromagnetic radiation emitted by other objects (such as the Sun, a light bulb or a fire). When electromagnetic radiation comes from an object (whether the radiation is emitted or reflected by the object) and enters the eye, we see that object. Everything you see around you either emits or reflects electromagnetic radiation or both.

Electromagnetic radiation comes in a wide range of frequencies (or wavelengths) and the frequencies of radiation the human eye is sensitive to is only a very small part of it. The collection of all possible frequencies of electromagnetic radiation is called the electromagnetic spectrum, which (for convenience) is divided into sections (such as radio, microwave, infrared, visible, ultraviolet, X-rays and gamma-rays).

The electromagnetic spectrum is continuous (has no gaps) and infinite. In practice, we can only use electromagnetic radiation with wavelengths between (very roughly) 10 -14 m (very high energy gamma rays) and 10 15 m (very long wavelength radio waves) due to technological limitations in the detectors used to receive electromagnetic radiation and in the devices used to produce or emit electromagnetic radiation.

The various frequencies (or wavelengths) of electromagnetic radiation coming from a particular object or material depends on how the object or material reflects and/or emits electromagnetic radiation.

Wave nature of em radiation

  1. List one source of electromagnetic waves. Hint: consider the spectrum diagram and look at the names we give to different wavelengths.
  2. Explain how an EM wave propagates, with the aid of a diagram.
  3. What is the speed of light? What symbol is used to refer to the speed of light? Does the speed of light change?
  4. Do EM waves need a medium to travel through?

[link] lists the wavelength- and frequency ranges of the divisions of the electromagnetic spectrum.

Electromagnetic spectrum
Category Range of Wavelengths (nm) Range of Frequencies (Hz)
gamma rays < 1 > 3 × 10 19
X-rays 1-10 3 × 10 17 - 3 × 10 19
ultraviolet light 10-400 7 , 5 × 10 14 - 3 × 10 17
visible light 400-700 4 , 3 × 10 14 - 7 , 5 × 10 14
infrared 700- 10 5 3 × 10 12 - 4 , 3 × 10 19
microwave 10 5 - 10 8 3 × 10 9 - 3 × 10 12
radio waves > 10 8 < 3 × 10 9

Examples of some uses of electromagnetic waves are shown in [link] .

Uses of EM waves
Category Uses
gamma rays used to kill the bacteria in marshmallows and to sterilise medical equipment
X-rays used to image bone structures
ultraviolet light bees can see into the ultraviolet because flowers stand out more clearly at this frequency
visible light used by humans to observe the world
infrared night vision, heat sensors, laser metal cutting
microwave microwave ovens, radar
radio waves radio, television broadcasts

Em radiation

  1. Arrange the following types of EM radiation in order of increasing frequency: infrared, X-rays, ultraviolet, visible, gamma.
  2. Calculate the frequency of an EM wave with a wavelength of 400 nm.
  3. Give an example of the use of each type of EM radiation, i.e. gamma rays, X-rays, ultraviolet light, visible light, infrared, microwave and radio and TV waves.

The particle nature of electromagnetic radiation

When we talk of electromagnetic radiation as a particle, we refer to photons, which are packets of energy. The energy of the photon is related to the wavelength of electromagnetic radiation according to:

Planck's constant

Planck's constant is a physical constant named after Max Planck.

h = 6 , 626 × 10 - 34 J · s

The energy of a photon can be calculated using the formula: E = h f or E = h c λ . Where E is the energy of the photon in joules (J), h is planck's constant, c is the speed of light, f is the frequency in hertz (Hz) and λ is the wavelength in metres (m).

Calculate the energy of a photon with a frequency of 3 × 10 18  Hz

  1. E = h f = 6 , 6 × 10 - 34 × 3 × 10 18 = 2 × 10 - 15 J

What is the energy of an ultraviolet photon with a wavelength of 200 nm?

  1. We are required to calculate the energy associated with a photon of ultraviolet light with a wavelength of 200 nm.

    We can use:

    E = h c λ
  2. E = h c λ = ( 6 , 626 × 10 - 34 ) 3 × 10 8 200 × 10 - 9 = 9 , 939 × 10 - 10 J

Exercise - particle nature of em waves

  1. How is the energy of a photon related to its frequency and wavelength?
  2. Calculate the energy of a photon of EM radiation with a frequency of 10 12  Hz.
  3. Determine the energy of a photon of EM radiation with a wavelength of 600 nm.

Questions & Answers

what are the factors that affect international organization
Imeobong Reply
Organizational structure,communication,mission
Ogunsola
what is international organization
Imeobong Reply
discuss how international organization affect business in Nigeria
Imeobong
An international organization is an organization with an international membership, scope, or presence.
Avishek
thanks
Imeobong
what are the factors that affect demand and commodity
Beatrice Reply
if a firm stays on the same isoquant it means ? a. output missteps decrease b. output must stay. the same c. output must increase d. quantity of labour and capital employed must remain the same e. none
Niza Reply
A
Were
A
alyssa
B
SEMAN
A
Darren
B
Bertilla
D
Romeo
which one is the right answer pls
Bertilla
😂😂😂😂
Niza
it's bad
Niza
B
Foley
d
Fasae
b
Alicia
a
Mohammed
hi
DINA
d
DINA
d) none. because isoquants meant different combination of inputs give same level of out and higher the isoquants gives higher the level of output
ezhilarasan
okay
Bertilla
analyse this table showing how this affect the law of diminishing demand return
michael Reply
What are diminishing marginal returns as they relate to costs?
michael
what are diminishing demand
Bertilla
please can you explain it to me because am new to economics
michael
the law of diminishing state that as more and more variable factor is added to a fixed cost, it will increase first and later its begins to fall until its get to zero. that were ur mc equal to zero
Fasae
thanks dr
Bertilla
The law of diminishing demand states that, if the price of a product is raised, a smaller quantity will be demanded and if the price of a product is lowered, a greater quantity will be demanded.
Were
The law of diminishing returns, also referred to as the law of diminishing marginal returns, states that in a production process, as one input variable is increased, there will be a point at which the marginal per unit output will start to decrease, ceteris puribus
Were
guys I need to know what is meant by basic economic mathematics and explain please
Lovemore Reply
It's also the usage of mathematical tools to express and analyse economic problems.
Rasaq
so basically it's the use of mathematical formulas to solve the problems under demand and supply right...
Lovemore
Yes, though economic analysis majorly has to deal with demand and supply forces in fact the back bone of economics rest on demand and supply but there are other functions like consumption function, implicit ,explicit, monotonic( constant, increasing, decreasing), transcendential, homogeneous, polyn
Rasaq
wat improvement do economic has with our life
Aminata Reply
it help us how to use our limited resources to satisfy our unlimited wants
Pagnol
Economics assit in understanding the pre-requisite for Growth and developmen and how the workings of the economy operates.
Rasaq
Economic helps us to manager our limited resources, how to expand it, etc over unlimited want
Eagle
Economics is the social Science in which we study how scarce resources are allocated for the betterment of human being.
Ali Reply
what is equilibrium point
Happiness Reply
where price and quantity demanded meet
Pagnol
is the point where price an quantity demanded meet
Aminata
why do consumer demand curve tend to move downward slope
Aminata
Equilibrium point is the point at which quantity demand equals quantity supply.
Rasaq
What is monopoly
Ezekiel Reply
Is a strict example of an imperfect market where there is only one seller and many buyer for a particular product.
Rasaq
what is economics
BUKENYA Reply
economics us behavior. Of people, nations, markets etc. It has much to do with reactions. watch MSNBC. Bloomberg. everyday they talk about how the markets react to an piece of news, legislation, interest rates etc. Interesting volatile stuff
TOM
but, it also react with science
ezhilarasan
economic is a science with study's the behavior of people,market and price
Bertilla
it's a science which study the behavior of people ,market n price
Bertilla
What is opportunity cost?
Junior
opp. cost~a benefit, profit or value of something that must be given up to acquire or achieve something else
Kim
or something that you foregone
Kim
who is the father of economic
Yirtutey Reply
Adam smith
shaikh
modern father is Adam smith
Bilal
Adam smith
Nazifi
what is backward bend
Florence Reply
It's a curve that reverses direction
Ajibade
Good evening friends
Kojo
Evening
Ajibade
evening
Emmanuel
hi
Lawrence
Any Nigerian lady to meet here Well on eco ground
Suleiman
Good morning ooo I hope everyone is fine
Kojo
hello
James
yeah
Kojo
how?
Kojo
how time
James
cool
Kojo
Ok
James
Good morning
Junior
morning all
Emeka
Morning
Ajibade
😶g
Maaz
moaz taha u r egyptian aren't u ?
Marwa
marwa no
Maaz
how economic effect the Market
Abdikarem
what is the difference between statistic and statistics?
Shafiu
One of the Principle of Economics states "Market is the best place to organize economic activies". However, market may fail if it does not perform it's necessary expected functions like Exercising real forces of demand and supply, contact where transactions are made etc. Though government may int
Rasaq
Through the Business cycle or the trade cycle.
Rasaq
it can can be described as when the demand is insufficient
Amaan Reply
high Dublin divino through Higginbotham
Shubham Reply
How does exchange rate affect the demand and supply?
austine
You mean demand and supply of currency ?
Jahangir
Hello
Hann
Hi
Jahangir
Am debby
Hann
am jahangir
Jahangir
how are you
Ogunsola
I am All fine Wbu ?
Jahangir
doing great
Ogunsola
Hw r u all
Mudassar
Am gud
Hann
Gd
Mudassar
Ogunsola
are you help for your country of economy leavel
Mutha
hi
Hammed
Hello
Assan
hi
Pranshi
Hello
Kamal
hi
Pranshi
hi
Abbas
hi
Abdirazak
ki sah botine
Neyshawn
hi
Nasir
Hello Economist
Nasir
hello
Victor
Hie... may anyone give me examples of countries that successfully implemented import substitution industrialisation.
Thabo
Nigeria
Junior
hey I'm emma from Uganda
niwagaba
Hello
Abraham
What is the difference between Demand and Quantity Demanded?
Weedh
Demand refers to how much a product is desired by buyer mean while quantity demanded refers to the amount of product a buyer is willing to buy at a certain price.
Junior
Good evening
Ajibade
Evening
Junior
evening
Ogunsola
someone wat is d textbook to read for banking and finance course
ayomide
Evening
Anjorin
Hw r u doing
Faku
yh
Benj
I'm good, u?
Anjorin
demand is the various quantity of goods or services a consumer is Willing and able to buy at a particular price over s given period of time while quantity demanded is the amount of goods or services being paid for
Florence
Good
Awudu
discuss how international organization affect business
Imeobong
Researchers demonstrated that the hippocampus functions in memory processing by creating lesions in the hippocampi of rats, which resulted in ________.
Mapo Reply
The formulation of new memories is sometimes called ________, and the process of bringing up old memories is called ________.
Mapo Reply
The fundamental frequency of a sonometer wire streached by a load of relative density 's'are n¹ and n² when the load is in air and completly immersed in water respectively then the lation n²/na is
Mukesh Reply
Properties of longitudinal waves
Sharoon Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Siyavula textbooks: grade 10 physical science [caps]. OpenStax CNX. Sep 30, 2011 Download for free at http://cnx.org/content/col11305/1.7
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Siyavula textbooks: grade 10 physical science [caps]' conversation and receive update notifications?

Ask
Danielrosenberger
Start Quiz