Lesson video

Hello, welcome to this lesson called dispersion of light and electromagnetic waves.

This is from the unit called electromagnetic waves.

And my name is Mr. Norris.

So in this lesson, we're gonna be thinking about a rainbow and rainbows.

People have always been fascinated by rainbows and seeing them in the sky, but in this lesson, we're not just gonna be looking at a rainbow, a spectrum of light, we're going to be going beyond the rainbow and to look at all the different kinds of electromagnetic waves.

So let's get going.

Here's the outcome for today's lesson.

By the end of the lesson, hopefully you'll be able to explain what's meant by the visible light spectrum and the spectrum of electromagnetic waves.

Here are some key words that will come up this lesson.

Electromagnetic waves, frequency, spectrum, refraction, and radiation.

And each word will be explained as it comes up in the lesson.

This lesson is split into two sections.

The first section is called the visible light spectrum, and the second section is called beyond the visible spectrum.

Let's get going with the first section.

So light can be thought of as a wave, and waves occur when something is disturbed or made to oscillate.

And then the disturbance or oscillation travels.

So like this rope here is being disturbed and made to oscillate, and the disturbance or oscillation travels down the rope.

But light waves are electromagnetic waves.

So they're similar to those waves on a rope or waves on a string.

But they're different because they're not oscillations of a rope and they're not oscillations of an object.

They're oscillations in or ripples in invisible electric and magnetic fields that are all around us.

So what do light sources? Things that give out light.

What do they actually do? Well, they disturb nearby electromagnetic fields a bit like what was disturbing that rope, except this is done to invisible electric and magnetic fields.

So the ripples from a light source, the ripples in electromagnetic fields travel outwards, transferring energy, and that's what light is.

Let's just go over some ideas about waves.

So the frequency of a wave is the number of oscillations that are happening per second, and that also gives the number of waves that arrive at a point per second.

So that's the frequency which is measured in hertz, capital H, little z for hertz.

And then the amplitude of a wave is the maximum displacement of a wave from the understood position and the wavelength of a wave which has given that Greek symbol, symbol lambda, that is the distance between one point on a wave and the same point the next wave.

So I've gone peak to peak here, but it doesn't have to be peak to peak, it could be trough to trough or any point on a wave and the distance between the same point on the next wave.

So the waves in that animation were transverse because the oscillations were up and down, but the waves were going along.

So the proper definition of that is you can't just say up and down and along, you've got to give that angle.

The oscillation is at 90 degrees to the direction of energy transfer.

So electromagnetic waves like light waves, they are transverse oscillations in electromagnetic field.

So the direction of oscillation is 90 degrees to the direction of energy transfer.

And what's important to remember is electromagnetic waves can have any frequency, and that's what the different colours of light are.

The different colours of light are just electromagnetic waves with different frequencies.

You can see in the diagram, there's a visible light spectrum or a rainbow.

So it's called a visible light spectrum, with a little frequency scale, that's rough.

It might not be quite exact, but it's been drawn on to indicate the different frequencies that the different colours of light have.

So a rainbow pattern of coloured light like this is called a visible light spectrum.

We need to get used to using that word spectrum, but of course the word spectrum just means a continuous range or scale.

If something is on a spectrum or there's like a spectrum, then that just means there's a range to choose from, and it might be a continuous range or scale.

So a visible light spectrum shows the full range of colours frequencies that visible light waves can have.

Shows the full spectrum all the possible frequencies of visible light.

So let's do a check on that.

Rainbows are said to contain seven colours traditionally, but in reality there's a continuous spectrum, there's a continuous range of colours.

So can you have a go at these two questions just to check your understanding of what we've just said so far.

Pause the video now, and then I'll see you once you've had a go at answering these two.

I'll give you some feedback now.

So the order of the seven colours of the rainbow kind of traditionally are red, orange, yellow, green, blue, indigo, violet.

And there are different ways you can use to remember the order of colours.

You might have heard there's a traditional saying that says Richard of York gave battle in vain where the first letters of each word match red, orange, yellow, green, blue, indigo, violet.

People often use ROYGBIV as, again, the first letters spell out red, orange, yellow, green, blue, indigo, violet.

But it's important to remember that although they're the seven traditional colours of the rainbow, in reality there's a continuous spectrum or range of colours.

All of those colours merge into each other on that continuous spectrum, continuous scale.

And which colour of light has the lowest frequency and which has the highest? Well, the lowest frequency is red light and the highest frequency in the spectrum, if we go for the seven colours of light in the rainbow is violet light.

Well done if you've got that.

Now let's talk about wavelength briefly.

The wavelength of any wave is set by the wave equation.

Wave speed equals the frequency times the wavelength, but of course in air or a vacuum, all electromagnetic waves, so all light waves have the same speed.

That's 300 million metres per second, or three times 10 to the eight metres per second.

So what that means, if frequency times wavelength always gives the same speed, then if waves have a higher frequency, they must have a lower wavelength to multiply to give the same speed.

So the bigger one gets the smaller, the other one gets by the same proportion.

They're inversely proportional, frequency and wavelength for electromagnetic waves.

So in one increases the other decreases to the inverse proportion.

So for example, a light wave with double the frequency would have half the wavelength.

Look at the diagram and make sure you're clear that the frequency scale runs upwards from red to blue, but the wavelength scale gets shorter from red to blue.

Okay, let's do a check of what we've just said.

So the seven colours of the rainbow are labelled in order here from left to right, red, orange, yellow, green, blue, indigo, violet.

So starting at red and moving through that spectrum to violet, in what order do the different colours of light appear? Choose the ones you think.

Off you go.

Okay, I'll give you some feedback now.

So starting at red and moving through the colour spectrum to violet, the colours appear in order of increasing frequency.

'Cause red light has the lowest frequency and violet light has the highest frequency.

The speed and air is the same for all electromagnetic waves, for all colour of light.

So it's not CLD, but it's also order of decreasing wavelength.

'Cause red light has the longest wavelength and violet light has the shortest wavelength.

Well done if you've got both of those.

So the sun and standard light bulbs give out white light, but white light is really a mixture of all the different frequencies, all the different colours of visible light.

So white light is really all the colours of light combined.

And this can be proved by passing white light through a triangular glass prism to produce a visible light spectrum like we've just seen.

So there's some white light going into this prism.

And a prism will split up the white light into a visible light spectrum like that.

That effect is called dispersion.

You can say the white light has been dispersed into the different colours.

It's a bit like the police could disperse a crowd and then everyone in the crowd goes their separate ways home.

Well, here the white light is being dispersed by the prism, and then all of the different frequencies of light that make up the white light, all the different colours of light then go their slightly separate ways and split up a little bit.

And just to prove that white light really is made up of the different colours of light, the second prism can then recombine the separated colours back into white light like this.

There's a second prism and it recombines the colours back into white light.

And that experiment was first performed and explained by Isaac Newton in about the year 1670.

Okay, let's do a check on what we've just said, which best explains this effect? Pause the video now and choose which option you think.

Okay, the option that best explains this effect is option C.

The prism splits up the white light into the different colours that the white light's made from.

It's not option D.

The red light does refract less and the violet light does refract more.

But the white light didn't change colour to red and violet, the red and violet was already there just in the white light ray and the prism split up those different colours.

So well done if you said C.

So in a triangular prism, violet light is refracted more than red light.

Is that true or false? Once you've decided, I then want you to justify your answer.

So which outta A or B best explains why you chose true or why you chose false? Is it because violet light waves have a higher frequency or is it because violet light waves have a lower frequency? Pause video now and choose true or false and also A or B.

Off you go.

Okay, I'll give you the answer now.

Violet light does refract more than red light.

So this statement was true.

And the best justification of that is that violet light waves have a higher frequency.

Well done if you got that correct.

Okay, time for a task now on this section of the lesson, this task has four parts and each part is quite simple.

So you should just be able to pause the video and have a go at all four parts of this task.

Sue you in a few moments.

Off you go.

Okay, I'm going to give you some feedback on this task now.

So question one at stake.

What is different about the different colours of light? The different colours of lights are all electromagnetic waves with different frequencies and different wavelengths, but it's the frequencies which are linked to the colours 'cause of course wavelength can change in different materials for each colour of light.

Question two: explain how white light is different to red light.

White light is a mixture of all the different frequencies of visible light, but red light is just one frequency or a narrow range of frequencies, you could say.

Part three: explain what is meant by the visible light spectrum.

Now a very simplistic answer would be a rainbow or a rainbow pattern of light, but we wanna give a bit more detail than that here.

So the visible light spectrum really means the full range, 'cause spectrum means range, the full range of different frequencies that visible light waves can have.

That's the visible light spectrum.

Part four of the task: add labels to the diagram of the prism to show which rays represent white, red, and violet light.

We should have the white light coming in.

The red light refracted the least, and the violet light refracted the most.

So that takes us to the second section of the lesson.

So we're now gonna go beyond the visible light spectrum to look at other frequencies that electromagnetic waves can have.

So human eyes can only detect electromagnetic waves in a limited frequency range, only between about 400 terahertz and just under 800 terahertz.

Now one terahertz is a million million hertz, so that's a very high frequency.

So the frequency of visible light waves is very, very high.

But what about all of the frequencies below 400 million million hertz, but below 400 terahertz? What about all the possible frequencies that are above 800 million million hertz, 800 terahertz? Because electromagnetic waves can have any frequency.

So electromagnetic waves with higher or lower frequencies, they're not detected by the human eye.

So they can be thought of as the same thing as light, but it's not light because you can't see it.

It's not visible light, it's in the invisible kinds of light.

So let's look at some examples of that.

So electromagnetic waves, the same thing as what light is, but with frequencies and range just lower than what the eye can detect, so just lower than red light, they're called infrared waves.

And the word infra means below.

So infrared electromagnetic waves are electromagnetic waves with a frequency that's just below the frequency of red light.

And electromagnetic waves with frequencies in a range just higher than violet light, so just higher frequency than the I can detect, they're called ultraviolet waves, and ultra means beyond.

So these are waves which are just beyond violet visible light waves in frequency.

So white light from the sun, we know it contains all of the frequencies of visible light, but it actually contains lots of infrared and ultraviolet frequencies of electromagnetic wave as well as those visible frequencies.

And you've probably heard of the sun's ultraviolet rays because that's what can cause sunburn if you stay in a sun for too long.

So we're actually gonna look at the infrared waves is sunlight first.

Now they can be detected by putting a sensitive thermometer just outside the red end of a visible light spectrum.

So look in the diagram to see where that thermometer's being placed.

And if you put thermometer there just outside the red end of a spectrum, its temperature goes up, but it's not absorbing any light from the sunlight because the light is split into the different frequencies of light from red to violet.

And we've put the thermometer outside of where any of that visible light goes.

So it must be absorbing an invisible kind of light.

It's actually absorbing infrared.

Now this is because each frequency present in sunlight is refracted a different amount.

And infrared frequencies are lower than the frequency of red light.

So infrared frequencies are refracted less than red light.

So that's why they appear just where they do just before red in the spectrum.

And the thermometer bulb absorbs infrared frequencies quite well.

So it's temperature increases when it's placed in the path of the infrared.

Let's do a check of what we've just been talking about.

So sunlight contains ultraviolet light as well as infrared and visible light.

And the ultraviolet light in sunlight will take the path shown through the prism.

So have a look at the diagram, make sure you can see where the ultraviolet light goes from the original beam of sunlight.

Now you all you need to do is decide which of the following statements are true A, B, and C.

So positive video now and make your decisions.

Okay, I'm gonna give you some feedback now, statement A, ultraviolet waves are higher frequency than violet light.

Well, we should know that that's true, but there's ultraviolet literally means beyond violet in frequency.

So higher frequencies than violet.

So that's true.

Well done if you've got that.

Statement B, ultraviolet waves are refracted more than violet light by a glass prism.

Well, that's true as well because the ultraviolet waves are refracted beyond violet.

So more than violet.

And statement C, ultraviolet waves are faster in air than violet light.

Well, that's not true because in air all electromagnetic waves have the same speed.

So ultra doesn't mean faster, it just means beyond and beyond violet in frequency.

Well done if you've got both of those right, A and B.

So really important idea now.

It turns out that all objects are actually constantly emitting or radiating electromagnetic waves into their surroundings.

That's right.

Everything in the room in front of you right now, every surface, every wall, the ceiling, every object on the desk in front of you, your own body is constantly emitting or radiating electromagnetic waves.

But the range of frequencies emitted and the intensities depends on an object's temperature.

And at room temperatures and below, objects don't emit any visible lights or higher frequencies than that.

They mainly actually emit infrared, which is invisible.

So that's why you can't see everyday objects glowing.

As the temperature of an object increases, the intensity of every frequency emitted also increases.

And also as a temperature of the object increases, the range of frequencies emitted increases to include higher and higher frequencies.

So the hotter an object is the more infrared is going to emit in a given time for both of those reasons.

And this is what thermal cameras detect.

You might have guessed that from the image on the previous slide repeated here.

So infrared cameras, what they actually do is they measure the intensity of infrared from each part of the image which corresponds to the temperature for the reasons given on the previous slide.

Colours are then added to a thermal image to show each temperature.

So a thermal image does not show us infrared itself.

It doesn't show us what infrared looks like.

It shows us which areas emit most infrared because they're the areas that should be painted the brightest colours normally on a thermal image, but the colours are added.

And we should make really clear at this point that infrared frequencies of electromagnetic wave are really easily absorbed by lots of different surfaces, including skin.

And that's gonna cause a heating effect when objects absorb infrared from their surroundings or from a hot object nearby.

And that heating effect and the energy transfer is caused without touching because the waves are electromagnetic waves, they can travel through air and through a vacuum really easily.

Now at around 600 degrees C, and it's the same temperature for all objects, objects start to emit some visible light as well as infrared.

And that's because increase the temperature of an object increases the range of frequencies emitted.

So the hotter object gets, the highest frequency is that's emitted, and eventually an object gets so hot that it starts to emit visible light as well as infrared.

And that's what happens to the heating elements inside a toaster or in the filament inside a light bulb, and the heating filaments of infrared heaters.

Now they might appear red or orange because they're hot enough to emit some red and orange visible light as well as the infrared that they're emitting.

Okay, time for a check now about what we just said.

Which of the following objects are remitting infrared? Choose from A, B, C, or D.

And also part two of this check, in which of the images can you see the emitted infrared? Pause video now and make sure you've got answers for part one and part two of this check.

Okay, let's see how you got on.

Which of the following objects are emitting infrared? They all are.

Okay, we said all objects, whatever their temperature are always emitting some infrared frequencies of electromagnetic waves into their surroundings.

And in which of the images can you see the emitted infrared? That's a bit of a trick question because none of them, because the infrared itself cannot be seen.

We can see that objects, the hot metal horseshoe and the bold filament, they are obviously hot enough to be giving out some visible light as well as infrared, but you cannot see the infrared from any object.

It's not detected by our eyes.

Well done if you've got both of those right.

Let's talk a bit more about ultraviolet now.

Light from the sun also contains ultraviolet or UV frequencies of electromagnetic wave.

And you might already know that exposure to too much ultraviolet, that's what causes sunburn.

And just like infrared, ultraviolet waves are not visible to humans.

Special amps that emit ultraviolet, they might look like they're violet, but that's because they emit some violet visible light as well as the ultraviolet they're emitting, which you can't see.

Some insects eyes can detect ultraviolet and some flowers reflect the suns ultraviolet to attract those insects.

So the top half of this image is a normal photograph of a dandelion flower.

Those bright yellow flowers you see in grass.

And the bottom half of that image is the same dandelion photographed, but it's captured the ultraviolet light.

So it's a false colour image.

You're not seeing the ultraviolet there.

The intensity of ultraviolet reflected from each part of the daisy has been measured and each number has been turned into a colour.

So we can kind of see which parts of the daisy are emitting most ultraviolet, but we're not seeing the ultraviolet itself in that picture.

You can see how those markings, which are only visible in ultraviolet, make like a nice target for insects to arrive in the very centre of the flower, probably where most of the pollen is.

And a final thing to mention about ultraviolet is that some substances are fluorescent and that means they give out visible light in the moments when they're absorbing ultraviolet light.

And that's how ultraviolet inks work, and glow in the dark decorations work in a similar way, but they stay glowing for longer after the exposure to ultraviolet has ended.

So again, objects which are fluorescent, maybe sometimes look violet, but that's maybe violet light they're emitting.

You are not seeing any of the ultraviolet there.

Let's do a quick check about some ideas about ultraviolet frequencies of electromagnetic wave.

So the writing in this image was written with ink that's invisible unless it's exposed to ultraviolet light.

So the question is, how does the exposure to the ultraviolet light cause the writing to become visible? Choose from A, B, and C.

Pause the video.

Off you go.

Okay, times for feedback on this one.

The correct answer was B.

The ink emits visible light when it's exposed to ultraviolet light.

So the ultraviolet light gets absorbed and that causes the ink to give out visible light.

So ultraviolet light is not pinky purple, it's invisible.

You can't see ultraviolet.

That's also why it's not A, because if the ink reflected the ultraviolet that hits it, you still wouldn't be able to see that.

So the only reason why ink glows is 'cause it emits visible light when it's exposed to ultraviolet light.

Well done if you've got that one.

So remember that we said that electromagnetic waves can have any frequency.

Well, so far we've only been talking about infrared, visible, and ultraviolet frequencies of electromagnetic wave.

But what about electromagnetic waves which have as low frequency as say a 100 hertz? Or what about electromagnetic waves which have an incredibly high frequency up to say 10 to the 22 hertz? That's a one with 22 zeros after it.

Number of oscillations per second frequency of 10 to the 22 hertz? Well actually all of these are possible and everything in between 'cause electromagnetic waves can have any frequency.

However, we give electromagnetic waves in different frequency ranges different names because they interact differently with different materials.

So the lowest frequency electromagnetic waves, we call them radio waves.

And that is exactly what carries radio signal, and TV signal, signal to a walkie-talkie, wifi signal is carried by radio waves, of course we can't see them.

And then in between radio waves and infrared waves, that frequency range which is missing, we call those microwaves for electromagnetic waves with those frequencies.

And don't confuse the microwave radiation, the microwave electromagnetic waves with a microwave oven, a microwave oven cooks food using microwave electromagnetic waves, microwave frequency, electromagnetic waves.

What about the very high frequency electromagnetic waves? Well, they're called X-rays and gamma rays if they're extremely high frequency electromagnetic waves.

So this is what I meant at the start of the lesson when we said electromagnetic waves can have any frequency, literally any frequency in this continuous spectrum of possible frequencies.

And we've said electromagnetic waves in the seven different frequency ranges, they're given different names because they interact differently with different materials.

And just an as an example of that, glass transmits visible light but absorbs infrared.

So if you want to hide from a thermal camera, you could hide behind a sheet of glass.

Any human could see you behind the sheet of glass because visible light is transmitted through glass, but you'd be invisible to a thermal camera 'cause the thermal camera would absorb the infrared that your body gives off and not let it get to the camera.

Whereas some kinds of opaque plastics can absorb visible light whilst transmitting some infrared.

So stars including the sun, are so hot and large that they produce electromagnetic waves in all seven frequency ranges at detectable intensities.

And you can use that to produce different kinds of images of the sun by using different kinds of telescopes that detect different frequencies of electromagnetic wave.

For example, that is a radio telescope that detects very long wavelength electromagnetic waves from objects in space.

And remember that the colours in images like this are gonna be false.

They're added by computers just so we can see which parts of the sun emit each frequency most intensely.

So we'll talk a bit about each of the frequencies of electromagnetic wave that we've mentioned.

So the lowest frequencies of electromagnetic wave are called radio waves.

And we've learned how to produce radio waves to transmit encoded information over long distances.

Radio, TV, phone, phone signal, and wifi.

Microwave frequencies of electromagnetic wave, they're produced in our homes to cook food in microwave ovens and they're also used for communications.

And then the highest frequency electromagnetic waves are called X-rays and gamma rays.

They're produced from changes in atoms in lots of materials.

An X-ray machine in a hospital can produce controlled bursts of X-rays to create an X-ray photograph.

So X-rays can pass through skin and flesh, but they're absorbed by bone.

That's how you can create a X-ray photograph.

And of course that's different to visible light and other kinds of electromagnetic waves which can't pass through skin and flesh.

Worth mentioning at this point, just a reminder that all frequencies of electromagnetic wave have the same speed in air and a vacuum, which is 300 million metres per second, three times 10 to the eight metres per second.

And what that means is that frequency and wavelength in air are inversely proportional for the entire spectrum of electromagnetic waves.

So when one of frequency and wavelength increases, the other must decrease to the inverse proportion so that the wave equation still works And frequency times wavelength still gives the same wave speed in air.

So here's an example of wavelength scale.

You can see that radio waves are the lowest frequency and longest wavelength electromagnetic wave.

Whereas gamma rays are very, very, very high frequency, but also very, very, very short wavelength.

So when you do frequency times wavelength, you still get the speed of light in air and a vacuum.

Let's do a check on some of the things we've just said.

Fill each blank with either the terms wave speed, wavelength, or frequency.

Pause video now and have a go at that.

There's just three blanks to fill in.

Off you go.

I'll talk you through this one now.

So radio waves, infrared, and ultraviolet are all the same thing as light: electromagnetic waves which is oscillations or ripples in electromagnetic fields.

But the only difference between each kind of electromagnetic wave is that frequency and wavelength and they could be either way round, and that causes each kind, each frequency range of electromagnetic wave to interact differently with different materials.

And all electromagnetic waves have the same wave speed in air and a vacuum.

Well done if you've got all of those.

Final thing we should just mention is that electromagnetic waves can also be called electromagnetic radiation.

Radiation just means something that's emitted and transfers energy away from a system.

So sound waves are acoustic radiation.

You can have a nuclear radiation and this is electromagnetic radiation, things which are emitted and transfer energy away from a system.

Electromagnetic waves counts as that.

And all kinds of electromagnetic radiation can be produced in nature.

For example, by stars, lightning, and hot objects.

Some living things actually produce electromagnetic radiation.

These jellyfish are emitting some visible light.

Electromagnetic radiation from the sun is naturally present at earth's surface.

So radiation's a completely natural thing, radiation from the sun is completely natural.

But of course, humans have also found ways of making each kind of electromagnetic radiation.

And the final thing we'll say is that the lower frequencies of electromagnetic radiation, we talk about radio waves, and microwaves, and infrared are not harmful unless the intensity is very high.

The higher frequencies of electromagnetic radiation, particularly ultraviolet x-rays, gamma rays, they can present a greater risk that the dangers produced if the exposure is minimised.

Let's do a check of some of the ideas we just talked about.

Which two of the following statements are true? So you're looking for two of these which are true and the rest are all false.

Pause the video, have a read through, make your decision, off you go.

I'll tell you which ones are true.

A was true: light is a kind of electromagnetic radiation.

Radiation just means something which is emitted and transfers energy, and light certainly is emitted from some objects and transfers energy away from those objects.

The other statement that's true is F, the sun does emit some harmful radiation.

Radiation is naturally occurring.

Radiation is not always dangerous and harmful.

There is potentially harmful radiation in the countryside such as ultraviolet from the sun, for example, hence very, very few electronic devices are going to emit harmful radiation because if they did, they wouldn't be allowed to be put on sale.

Okay, well done.

Lots of information about different kinds of electromagnetic waves with the different frequencies.

So there are four parts to this task to complete this lesson.

Most of the parts of this task are fairly straightforward, so you pulls the video now and have a go at each part.

Off you go.

Well done for your effort on that task.

I'll give you some feedback now.

So what is meant by the spectrum of electromagnetic waves? It means the full or continuous range of frequencies that electromagnetic waves can have.

The spectrum of frequencies that electromagnetic waves have, which is all possible frequencies.

Part two was just adding the names of the seven frequency ranges of electromagnetic waves to the diagram.

Should have gone starting from the lowest frequency electromagnetic waves, that's radio waves, then microwaves, then infrared, then visible light, then ultraviolet, then x-rays, then gamma rays as shown in this diagram here.

Part three of this task, describes some properties that all electromagnetic waves have.

Hopefully you've included some of these.

So all electromagnetic waves consist of oscillations or ripples in electromagnetic fields.

That's what they are.

Electromagnetic waves are transverse waves, and in air or a vacuum, they all travel at the speed of light, 300 million metres per second, three times 10 to the eight metres per second.

And all electromagnetic waves transfer energy.

Well done if you've got most or all of those.

And part four of this task state the only difference between each kind of electromagnetic wave that causes them to interact differently with different materials, what we're looking for here is their frequency.

You might have mentioned their wavelength, but really they're defined by their frequency rather than their wavelength.

Here's a summary of the lesson.

Electromagnetic waves or electromagnetic radiation are transverse oscillations or ripples in electromagnetic fields.

Light is electromagnetic radiation that we can see.

Colours in the visible spectrum have different frequencies.

Violet light has the highest frequency and refract more than red light in glass.

Electromagnetic waves in other frequency ranges interact differently with different materials.

In order of frequency, starting with the lowest frequency, the spectrum of electromagnetic waves is radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays.

And all electromagnetic waves can transfer energy and they all travel at the same speed in air.