Electromagnetic Spectrum Explained - Gamma X rays Microwaves Infrared Radio Waves UV Visble Light

Summary

This 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

00:00

🌌 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.

05:01

🔬 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.

10:01

⚡ 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.

15:03

🔄 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.

Keywords

💡Electromagnetic Spectrum

The electromagnetic spectrum refers to the range of all types of electromagnetic radiation, which is the substance that travels through space as both waves and particles. In the video, the electromagnetic spectrum is the central theme, as it is ordered from radio waves with the lowest energy to gamma rays with the highest energy. The script explains how energy, frequency, and wavelength are interrelated and how they change across the spectrum.

💡Radio Waves

Radio waves are a type of electromagnetic radiation with the lowest energy and the longest wavelengths. They are mentioned as the starting point of the electromagnetic spectrum in the video. Radio waves are used in various communication technologies, such as broadcasting and radar systems.

💡Microwaves

Microwaves are a form of electromagnetic radiation with wavelengths shorter than radio waves but longer than infrared light. They are positioned after radio waves in the spectrum. In the script, microwaves are mentioned as part of the progression from lower to higher energy waves.

💡Infrared

Infrared radiation lies between microwaves and visible light in the electromagnetic spectrum. It has a higher frequency than microwaves but is not visible to the human eye. The video script uses infrared as an example to illustrate the increase in frequency as one moves across the spectrum.

💡Visible Light

Visible light is the portion of the electromagnetic spectrum that humans can perceive, ranging from red to violet. The script describes the visible light spectrum as having colors such as red, orange, yellow, green, blue, and violet, emphasizing the transition from one color to another and their positions in the spectrum.

💡Ultraviolet Rays

Ultraviolet (UV) rays are a form of electromagnetic radiation with a higher energy than visible light but lower than X-rays. They are located just beyond the violet end of the visible light spectrum. The video script explains that UV light has a higher frequency than infrared, indicating its position in the spectrum.

💡X-rays

X-rays are a type of high-energy electromagnetic radiation that has a shorter wavelength than ultraviolet light. They are used in medical imaging and other applications. In the script, X-rays are mentioned to illustrate the increase in energy and decrease in wavelength as one moves further along the spectrum.

💡Gamma Rays

Gamma rays are the most energetic form of electromagnetic radiation, with the shortest wavelengths. They are positioned at the end of the spectrum discussed in the video. The script explains that gamma rays have more energy than X-rays, indicating their high-energy status.

💡Cosmic Radiation

Cosmic radiation refers to high-energy particles and waves originating from outer space. In the video script, cosmic radiation is mentioned as being beyond gamma rays in terms of energy, although it is not part of the standard electromagnetic spectrum.

💡Frequency

Frequency, measured in hertz (Hz), is the number of oscillations or cycles per second of a wave. The script explains that frequency increases as one moves from left to right across the electromagnetic spectrum, with higher energy waves like gamma rays having higher frequencies than lower energy waves like radio waves.

💡Wavelength

Wavelength is the distance between two consecutive points in a wave that are in the same phase. The video script describes how wavelength is inversely related to frequency and energy, with longer wavelengths corresponding to lower energy and frequency, as seen with radio waves, and shorter wavelengths to higher energy and frequency, as with gamma rays.

💡Photon

A photon is a quantum of light and other electromagnetic radiation, exhibiting both particle and wave properties. The script uses the concept of a photon to explain energy levels, with the example of a blue photon having more energy than a red photon due to its position on the spectrum.

💡Planck's Constant

Planck's constant is a fundamental physical constant that relates the energy of a photon to its frequency. The script introduces Planck's constant in the equation E = hf, where E is the energy of a photon, h is Planck's constant, and f is the frequency. It is used to calculate the energy of photons at different frequencies.

💡Speed of Light

The speed of light is a universal physical constant that represents the speed at which light propagates through a vacuum, which is approximately 3 x 10^8 meters per second. The video script uses the speed of light in the equation c = λf to explain the relationship between wavelength, frequency, and the constant speed at which all electromagnetic waves travel in a vacuum.

💡Index of Refraction

The index of refraction is a measure of how much light slows down and bends when it passes through a medium other than a vacuum. In the script, the index of refraction is used to explain how the speed of light changes in different materials, such as water or diamond, affecting the speed of light and thus the behavior of electromagnetic waves.

💡Energy Conversion

The script discusses the conversion between different units of energy, such as joules and electron volts, which is important for understanding the energy of photons in different contexts. For instance, the energy of a photon is calculated in joules and then converted to electron volts for comparison with other energy levels.

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.