Electromagnetic Spectrum Explained - Gamma X rays Microwaves Infrared Radio Waves UV Visble Light
Summary
TLDRThis educational video script delves into the electromagnetic spectrum, sequentially explaining the progression from low-energy radio waves to high-energy gamma rays and cosmic radiation. It clarifies the inverse relationship between wavelength, frequency, and energy, emphasizing how these properties shift across the spectrum. The script also covers the calculation of photon energy and frequency, using Planck's constant and the speed of light, and demonstrates conversions between different units of energy, such as joules and electron volts.
Takeaways
- 📡 Radio waves have the lowest energy and the longest wavelength.
- 🌡️ As you move to the right on the electromagnetic spectrum, the energy and frequency of waves increase.
- 🌈 The visible light spectrum includes red, orange, yellow, green, blue, and violet.
- ☢️ Gamma rays have more energy than x-rays, and they lie on the far right of the spectrum.
- 🔄 Wavelength increases to the left, so radio waves have a longer wavelength than microwaves.
- 🔵 A blue photon has more energy than a red photon because it's further right on the spectrum.
- 📉 Infrared radiation has a higher frequency than microwaves.
- 🩻 X-rays have a longer wavelength than gamma rays.
- 🌞 Ultraviolet radiation has more energy than microwaves.
- 🌪️ Gamma rays have a lower frequency than cosmic radiation.
Q & A
What is the electromagnetic spectrum?
-The electromagnetic spectrum is the range of all types of electromagnetic radiation, arranged by frequency or wavelength. It includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays, and cosmic radiation.
Why are radio waves considered to have the lowest energy in the electromagnetic spectrum?
-Radio waves have the lowest energy because they have the longest wavelength. As you move to the right in the spectrum, the energy increases, with gamma rays having the most energy.
What is the order of the electromagnetic spectrum from lowest to highest energy?
-The order from lowest to highest energy is: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays, and cosmic radiation.
Which part of the visible light spectrum has the highest frequency?
-Violet light has the highest frequency in the visible light spectrum, as it is on the right side of the spectrum where frequency increases.
How does the energy of a photon compare between a red and a blue photon?
-A blue photon has more energy than a red photon because it is on the right side of the spectrum, where energy increases.
What is the relationship between wavelength, frequency, and energy of a photon?
-As wavelength increases, frequency and energy decrease, and vice versa. A short wavelength corresponds to a high energy photon and a high frequency, while a long wavelength corresponds to low frequency and low energy.
What is Planck's constant and how is it used in calculating the energy of a photon?
-Planck's constant is approximately 6.626 x 10^-34 joules seconds. It is used in the equation E = hν (where E is energy, h is Planck's constant, and ν is frequency) to calculate the energy of a photon.
How does the speed of light change when it travels through different media?
-The speed of light changes based on the medium's index of refraction. For example, light travels slower in water (with an index of refraction of 1.33) and even slower in diamond (with a higher index of refraction) compared to its speed in a vacuum, which is approximately 3 x 10^8 meters per second.
How can you calculate the frequency of a photon given its wavelength?
-You can calculate the frequency of a photon using the equation ν = c / λ, where c is the speed of light and λ is the wavelength. The frequency is obtained by dividing the speed of light by the wavelength.
What unit is used to measure the energy of a photon, and how is it related to joules?
-The energy of a photon is often measured in electron volts (eV). One electron volt is equal to 1.602 x 10^-19 joules. To convert joules to electron volts, you divide the energy in joules by 1.602 x 10^-19.
How can you find the wavelength of a photon if you know its energy?
-You can find the wavelength of a photon using the equation E = h(c / λ), where E is the energy, h is Planck's constant, and c is the speed of light. By rearranging the equation, you can solve for λ (wavelength) as λ = hc / E.
Outlines
🌌 Introduction to the Electromagnetic Spectrum
This paragraph introduces the concept of the electromagnetic spectrum, detailing its various components in order of increasing energy and frequency. It starts with radio waves, which have the lowest energy and longest wavelength, and progresses through microwaves, infrared, visible light (including the colors of the spectrum and the concept of indigo being abbreviated as 'v'), ultraviolet, X-rays, gamma rays, and cosmic radiation. The key takeaway is the inverse relationship between energy/frequency and wavelength: as one increases, the other decreases. The paragraph also poses questions to test understanding, such as comparing the energy of different photons and types of electromagnetic radiation, and explains the fundamental equations that relate wavelength, frequency, and energy.
🔬 The Relationship Between Light Speed, Wavelength, and Medium
This section delves into how the speed of light is affected by different mediums, using water and diamond as examples with their respective indices of refraction. It explains that light travels slower in mediums other than a vacuum, and provides the formula for calculating the speed of light in a medium. The paragraph also revisits the equations relating photon energy to Planck's constant and frequency, and demonstrates how to calculate the frequency of a photon given its wavelength, using the example of a red photon with a wavelength of 700 nanometers. The process involves converting units from nanometers to meters and applying the formula for frequency, resulting in the frequency of the red photon being calculated as 4.286 x 10^14 hertz.
⚡ Calculating Photon Energy and Units Conversion
The paragraph focuses on calculating the energy of a photon using its frequency and Planck's constant. It provides a step-by-step guide on how to find the energy of a red photon based on the previously calculated frequency, resulting in an energy of 2.84 x 10^-19 joules. The summary also covers the conversion of energy units from joules to electron volts, using the provided conversion factor. The process demonstrates the direct proportionality between frequency and photon energy, and includes an example calculation for a blue photon with a wavelength of 480 nanometers, yielding an energy of approximately 2.585 electron volts after conversion.
🔄 Reverse Calculations from Energy to Wavelength
This final paragraph presents a reverse calculation scenario where the energy of a photon is given, and the task is to find its frequency, wavelength, and equivalent energy in different units. The example starts with a photon energy of seven electron volts, converting it to joules, and then calculating the frequency using the energy and Planck's constant. With the frequency determined, the wavelength is found by rearranging the speed of light equation. The summary concludes with the conversion of the calculated wavelength from meters to nanometers, providing a clear method for unit conversion and emphasizing the additive property of exponents in such calculations, resulting in a wavelength of 177.3 nanometers.
Mindmap
Keywords
💡Electromagnetic Spectrum
💡Radio Waves
💡Microwaves
💡Infrared
💡Visible Light
💡Ultraviolet Rays
💡X-rays
💡Gamma Rays
💡Cosmic Radiation
💡Frequency
💡Wavelength
💡Photon
💡Planck's Constant
💡Speed of Light
💡Index of Refraction
💡Energy Conversion
Highlights
Introduction to the electromagnetic spectrum, starting with radio waves and explaining their properties as the lowest energy and longest wavelength.
Explanation of microwaves and their position in the spectrum following radio waves.
Description of the infrared spectrum and its role after microwaves in the electromagnetic sequence.
Overview of the visible light spectrum, including the colors red, orange, yellow, green, blue, indigo, and violet.
Differentiation between ultraviolet rays, X-rays, and gamma rays in terms of their energy and position in the spectrum.
The concept that energy and frequency increase as you move to the right on the electromagnetic spectrum.
Illustration of how wavelength increases as you move to the left on the spectrum, with radio waves being longer than microwaves.
Question and answer format to determine which photon has more energy, a blue or red photon, emphasizing the position of blue light on the spectrum.
Comparison of microwaves and infrared radiation to determine which has a higher frequency, concluding with infrared's higher frequency.
Explanation of why X-rays have a longer wavelength than gamma rays when moving to the left on the spectrum.
Discussion on the energy comparison between microwaves and ultraviolet radiation, with ultraviolet having more energy.
Clarification on the lower frequency of gamma rays compared to cosmic radiation, despite both being on the high-energy end of the spectrum.
Analysis of the wavelength comparison between yellow and green light, concluding that green light has a shorter wavelength.
Explanation of the relationship between wavelength, frequency, and energy, and how they are inversely related.
Presentation of the fundamental equations relating wavelength, frequency, and the speed of light.
Description of how the speed of light changes in different mediums due to the index of refraction.
Calculation of the frequency of a red photon given its wavelength, demonstrating the use of the speed of light equation.
Conversion of units from nanometers to meters for accurate scientific calculations.
Determination of the energy of a photon using Planck's constant and the calculated frequency.
Conversion of energy from joules to electron volts for alternative representation.
Direct calculation of a photon's energy from its wavelength using combined equations.
Problem-solving example: calculating the energy of a blue photon with a wavelength of 480 nanometers.
Reverse calculation from energy in electron volts to joules, frequency, and wavelength in nanometers.
Final summary of the process to convert meters to nanometers for wavelength calculations.
Transcripts
in this video we're going to go over the
electromagnetic spectrum
so we're going to go in order
the first one you need to know
are radio waves
radio waves have the lowest energy but
the longest wavelength after radio waves
there are microwaves
and then
it's infrared
after infrared you have the visible
light spectrum
you have color such as red
orange
yellow
green
blue
violet this indigo and violet but i'm
just going to put v for violet
after violet you have ultraviolet rays
and then you have x-rays
and then gamma rays
and then after gamma you have cosmic
radiation
what you need to know is that as you go
to the right
the energy increases
so gamma rays have more energy than
x-rays
as you go to the right the frequency
increases as well
so ultraviolet light has a higher
frequency than infrared
as you go to the left
the wavelength increases
so radio waves are longer than
microwaves
so here are some questions
which photon has more energy
a blue photon or a red photon a photon
is simply a particle of light
so the one that has more energy is the
one that's on the right side
so if we compare a red photon to a blue
photon the blue photons on the right
side so the blue photon has more energy
now which one has a higher frequency
microwaves or infrared radiation
frequency increases as you move to the
right so infrared radiation will have
a higher frequency
now which one has a longer wavelength
x-rays or gamma rays
wavelength increases to the left
so x-rays
has a longer wavelength
all right so let's try some more
questions which one has more energy
microwaves
or ultraviolet radiation
so energy increases to the right it's
going to be uv light or ultraviolet
radiation
now which one has
a lower frequency
gamma rays are cosmic radiation
frequency increases to the right so the
one with the lower frequency is gonna be
on the left side that's a gamma rays
now which one has
a shorter wavelength
yellow light or green light
the wavelengths increase to the left but
they decrease to the right so the
shorter wavelength is going to be on the
right side
and so that's
green
a green photon is going to be shorter in
wavelength than a yellow photon
now you need to know the relationship
between
wavelength frequency and energy
the wavelength is represented by the
lambda symbol
as the wavelength increases
the frequency will decrease
and also the energy of the photon
will decrease as well
if the wavelength decreases
the frequency and the energy
will increase
so a short wavelength corresponds to a
high energy photon
and a high frequency
a long wavelength corresponds to low
frequency and low energy
the equations that relate these
variables together
are these two equations
the speed of light is equal to
lambda times
v v is the same as frequency so if you
want to you can write f for frequency
c is the speed of light
for electromagnetic waves
they travel in space
at a speed of 3 times 10 to the 8 meters
per second that's an empty vacuum
light however
can change its speed when it travels in
a different medium for example
light travels slower
in water the speed of light changes
in a material based on its index of
refraction
so whenever you see the c variable this
is a constant
it's always 3 times 10 to the 8.
v is the velocity
of light in a certain material
so in water
water has an index of refraction of 1.33
that's the end value
so the speed of light in water is going
to be 3 times 10 to the 8 meters per
second divided by 1.33
which is about
2.26 times 10 to 8 meters per second
so light travels slower in a different
medium
diamond which has a much higher index of
refraction i believe it's like 2.4
the light travels even slower in diamond
than it does in water but in empty space
in air
the speed of light is three times ten to
the eight in a vacuum
now there are some other equations that
you need to know
here's another one
the energy of a photon is equal to
planck's constant times the frequency
you might see v for frequency if you're
taking chemistry
planck's constant is equal to 6.626
times 10 to the negative 34
joules times seconds
so let's work on some typical problems
let's say
if you have a wavelength
of around
700 nanometers
this corresponds to a red photon
so given the wavelength of this red
photon
calculate the frequency of the photon
so we need to use the equation c is
equal to lambda times f
so the frequency is equal to the speed
of light divided by the wavelength
so it's going to be 3 times ten to the
eight meters per second
divided by
now what number should we plug in for
the wavelength
should we plug in seven hundred
notice the units
is in nanometers however for the speed
of light we have the units meters if we
plug in 700 at this point
we're gonna have a mismatch in terms of
units so
we need to convert nanometers into
meters
it turns out that one nanometer
is equal to one times ten to the minus
nine meters
so what we need to plug in is seven
hundred
times ten to the negative nine meters
all you have to do is insert
the ten to the negative nine replace it
with nanometers
and that's a simple way of
converting from nanometers to meters
just add the ten to negative nine to it
so let's calculate the frequency three
times ten to the eighth divided by 700
times 10 to the negative 9
and you should get
a frequency of
4.286 times 10 to the 14
hertz
the unit hertz is the same as one over
seconds or
s to the minus one
you can't write it both ways but you can
write it as hertz or s to the minus one
as you can see when we divide the speed
of light by the frequency i mean by the
wavelength the meters cancel
and you get one over s
which is
equal to the unit hertz
so now that we have the frequency of the
photon
let's calculate the energy of the photon
so let's use this equation e is equal to
h f
so based on the equation you can see
that as f increases e increases
these two are directly related
so let's plug in planck's constant 6.626
times 10 to the negative 34
and we're going to put the units joules
times seconds
and then we're going to multiply by the
frequency of 4.286
times 10 to the 14 hertz or
1
over seconds
so notice that the unit seconds cancel
so we're going to be left with the unit
joules
which is
the unit for energy
so if you multiply those two numbers
you should get
2.84
times 10 to the negative 19 joules
so now you know how to calculate the
energy of a photon
now sometimes the energy of the photon
may be represented in a unit called
electron volts
so let's convert joules to electron
volts the conversion factor
is 1.602 times 10 to the negative 19
joules
is equal to one
electron volt
so let's start with the number that we
have
in the next fraction we're going to put
the conversion factor
since we have joules on the top left
we need to put the unit joules on the
bottom
so for every 1.602 times
10 to the negative 19 joules
we have one
electron volt
so we need to divide
so you should get
1.773
electron volts
here's another question for you
so let's say if you have
a blue photon with a wavelength of
480 nanometers
how can you use this wavelength to
calculate the energy of a photon
directly
so let's combine the equations e is
equal to h f
planck's constant times frequency
and c is equal to lambda f
if we solve for frequency in the second
equation
we'll see that frequency is the speed of
light divided by the wavelength
so we can replace f with c over lambda
so therefore the energy of a photon
is planck's constant times the speed of
light divided by wavelength
that's how you could find the energy
directly from wavelength
so now let's solve it so it's going to
be planck's constant
the speed of light which is 3 times 10
to the 8
meters per second
divided by the wavelength don't just
plug in 480 nanometers make sure you
convert it to meters
so
you just simply write 480 times 10 to
the negative 9 meters
and then we just got to type it in the
calculator 6.626 times
10 to the negative 34 times the speed of
light
divided by the wavelength at meters
will give you an answer of
4.14 times
10 to the negative 19 joules
now to convert that to electron volts
divide that number by 1.602
times 10 to the negative 19
and so this is about 2.585
electron volts
so here's another problem let's work
backwards
so if you have a photon
with an energy of seven electron volts
calculate the energy in joules
calculate the frequency
and calculate the wavelength
in
nanometers
feel free to pause the video and work
out this example
so to convert electron volts into joules
this time
we need to multiply
by 1.6 times 10 to the negative 19.
notice that the unit electron volts
cancel
and you should get
1.12 times 10 to the negative 19.
actually not 19 but 18
joules
now once we have the energy we could
find a frequency
using this equation
so solving for f the frequency is
the energy divided by planck's constant
so it's going to be the 1.12 times 10 to
the negative 18
joules divided by
6.626
times 10 to the negative thirty four
so therefore the frequency
is
1.692
times 10 to the 15
hertz
so now that we have the frequency we can
find the wavelength
using this equation c is lambda times
frequency
so the wavelength is the speed of light
divided by frequency if you rearrange
the equation
so it's going to be 3 times 10 to the 8
meters per second
divided by
1.692 times 10 to the 15 hertz
or
one over seconds
so as you can see the unit seconds
cancel
leaving behind meters which is the unit
for wavelength
so if you divide those two numbers
you should get
a wavelength of
1.773
times ten to the negative seven
meters
now to convert it back to nanometers
we know that
one nanometer
is
1 times 10 to the negative 9
meters
so these units cancel
and for this we really don't need a
calculator to perform this calculation
if we take this
number the 10 to the negative nine if we
move it to the top then negative nine
becomes positive nine
so what we now have
is one point seven seven three times ten
to negative seven
times ten to the positive nine
when you multiply two common bases
you're allowed to add the exponents
negative seven plus nine is two
so the wavelength
is one point seven seven three times ten
square ten squared is a hundred
so it's simply
177.3
nanometers
so to quickly convert from meters to
nanometers
simply add 9 to this exponent
so negative 7 plus 9 will give you the
positive 2.
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