X Rays - A Level Physics

[@tpodan79]

You explain so clearly in 18 minutes what took my teacher 50 minutes to explain and I still didn't get it. Thank you for an excellent explanation!

[@DrPhysicsA]

Thank you for your very kind comments. I'm very glad that it helped.

[@jacktoholke6378]

Thank you so much! Very well X-plained!

[@AS-qi2lq]

I see what you did there.

[@bikermoofrommars5922]

I'm a dental nurse studying for my radiography qualification and have been struggling with understanding some areas of physics. Just wanted to say how amazing this video is, and I'll be watching on repeat and taking revision notes from this ( aswell as my textbook of course!). Thanks so much

[@DrPhysicsA]

Hi Jake - Thanks for your kind comments. I would be very happy to do the videos you suggest but I'm afraid I cant do them in time for Monday and probably not for another week or so. But good luck in your exam. I hope it goes well.

[@DrPhysicsA]

In general ionisation means that an electron has been knocked out of an atom so that the atom is positively charged (ionized). Excitation means that the electron has been pushed up to a higher energy level (but still within the atom). The atom still has all its electrons and is not ionised. But the excited electron will soon fall back to a lower energy level emitting a photon.

[@MrKb7373]

Good simple explanation and useful practical/clinical tips. Just to correct one mistake DrPhysicsA in your explanation from 14:15 to 14:35, when x-rays strike the radiographic film it is blackened, not whitened or grayed. That is why the shadow of bone on the radiograph appears white or grey because the x-rays are attenuated by the dense bone. However the soft tissues do not stop the x-rays at all from penetrating hence that part of the radiographic film appears black.

[@DrPhysicsA]

Yes. There is the braking radiation. But the main X rays come from high energy electrons knocking electrons from the inner shells of the anode. Outer shell electrons can then fall down the energy level to take the space vacated by the electron. This fall in energy is released as a photon - in this case in the X ray wavelength range.

[@DrPhysicsA]

My A Level Physics revision playlist has videos on Gravitation and Electricity, both of which refer to the inverse square law for Newton's or Coulomb's laws.

[@DrPhysicsA]

Ionisation is where the energy given to the electron (eg from a photon) is sufficient to kick the electron completely out of the atom. The atom therefore has a residual positive charge. Excitation is where the photon gives enough energy to promote the electron to a higher energy level but still in the atom.

[@valdemirpelegrinello7149]

Amazing explanation clearly and easy to understanding. Thank You so much

[@anikasanjana6912]

This is so amazing! These explanations follow the exact contents which are in the application booklet, also maintaining the serial. Loved it!

[@DrPhysicsA]

Thanks. Nice to know its recommended by your professor.

[@NWin86]

Thank Dr for uploaded this kind of professional lecture. It help me a lot.

[@DrPhysicsA]

Where x-rays are produced as a result of electrons falling from outer energy levels to inner energy levels then this will be a constant process because energy is constantly being given to the atom to enable electrons to jump up to the higher energy levels in the first place.

[@JennyCheng0102]

i learned so much in your video! biomedical imaging is making sense now! thank you!

[@DrPhysicsA]

How kind. Glad it was of some help. All good wishes for your studies.

[@a7med4s]

Perfect presentation,perfect demonestration I am so happy to watch this DrPhysicsA you are simply incredible

[@jakerichardson625]

Thanks anyway! Most of your videos cover most of the stuff, and have really made a difference for me. Thanks again

[@DrPhysicsA]

Thanks. In my efforts to show where the X rays would penetrate and where they wouldn't I didn't properly cover their impact on the photographic plate. I've added an annotation.

[@1002em]

this is ridiculously helpful. thank you so much for these videos!

[@annagute7681]

The best x-ray explanation ever, THE BEST !

[@Mufti199]

U, my friend, are a life saver

[@IMrNuminous]

Glad I found these in time for my G485 exam, really good explanation. Feels like im getting a physics lecture off bruce forsyth :)

[@benjamincharles5492]

WOW! This is the best explanation of X-Rays...!! Thank you!

[@DrPhysicsA]

My videos certainly cover the OCR syllabus but they all so cover material in the AQA and Edexcel syllabus as well as some material in the Cambridge syllabus.

[@jakerichardson625]

Hi I'm an A Level student and I have my AQA unit 5 exam on Monday, I find your videos so helpful. I learn more after watching them than I've learnt in all my lessons on those topics. If you have time would you be able to do some videos on other Medical Physics topics? such as the eye, ear, and heart? This is the stuff on my syllabus, if you could make a video on anything on here it would be extremely helpful!

[@andresjimenez3026]

Excellent video, has a wonderfully concise explanation.

[@danielholden6849]

Thankyou for the great video, it really did help! I am just slightly confused with the graph. You said that were the minimum wavelength are seen high energy x-rays occur. On the y-axis there is intensity, so does that mean the x-rays produced on the left side of the graph have an high energy but low intensity?

[@DrPhysicsA]

Thanks. Nice to have it explained.

[@EllieGouldingFan]

I have the same exam on Monday - thank you so much for these videos! Good luck for Monday everyone! :)

[@ilaydamumcuoglu8339]

finally I understood how x-rays work thank you so much for this amazing video

[@DrPhysicsA]

Thanks. HIgh and low energy photons will enter the body but low energy X rays will be wholly absorbed and not appear on the photographic plate. High energy will be attenuated but will still pass thro the body. So low energy X rays add to the overall dose but for no worthwhile effect.

[@vicky.medrano]

Best comprehensive explanation I've found. Thanks so much!! Just one critique; video quality ;)

[@syed5126]

Vicky Medrano its was made in 2012 what do you expect?

[@DrPhysicsA]

I'm stumped on that one I'm afraid. I guess the answer has to do with the technology and which element best provides the Xrays which are most suitable for medical purposes. But I could be wrong. Anyone else know?

[@DrPhysicsA]

Which A Level syllabus are you following?

[@razamate]

That was a really good explanation of xrays! Thank you very much!

[@thecontroller6786]

Great video!! Thank you so much for your explanation... All of your vids are all well-explained.

[@ericpupek9044]

watched a ton of videos on x rays and sorry to say their are a ton of really bad Physics teachers out there, BUT your videos was awesome. Thank you I HIGHLY recommend.

[@PaiigeeYeaah]

Ahhh everything makes so much more sense now! A big thank you to you!!!! :)

[@DrPhysicsA]

Have you looked at "Attenuation coefficient" on Wikipedia?

[@moyrml]

that last part got me thinking about orthographic projection. is that grating essentially creating an ortho look? if it does then, is it possible to create an ortho-lens in that manner to attach to a regular (visible-light) camera? btw, great video, thank you!

[@gautomdas9172]

Very very good one . just love it.

[@leeannhunt9122]

Wonderful explanation! This was super helpful!

[@vidulanarampanawa2540]

My ideal teacher of physics

[@pynewill]

Great video, but what about X-ray attenuation and image intensifiers, also contrast media and CAT scans are in the textbook

[@adarshk19]

Hello awesome video that complemented my textbook and brought life to the application section of my physics course. Is there a video about the attenuation of X-rays? Like where we use the formula to fine resultant intensity and so on? thanks

[@ibrahimawadallah]

Helpful video. Thanks. I suggest you use high resolution camera, and a better lighting.

[@floridanews8786]

Beautiful explanation!

[@nooli72]

My professor recommanded your video. thanks for great video.

[@DarkLevis]

Your welcome. I understand this but I assume there's a deeper reason to this. I'm guessing that low energy photons 'frequency' causes some interaction (resonace?) with molecules more easily that high 'frequency' does. Or is it just explain cause high freuquency photons pass due to having more energy(as some being absorbed but even few which pass leave a mark on plate) or even some other way? Thanks a lot!

[@MrKb7373]

You can add this correction as tag to your video for those minutes. [Reference: 'Nature of the radiographic image', pg. 3, Essentials of Dental Radiography and Radiology by Eric Whaites, 4th edition.]

[@twchen0402]

Dear DrPhysicsA: From the video, are you meaning the x-ray generation from the acceleration of electron beams is equivalent to that from the energy transition of the outer shell back into the inner shell. They are of the same, but different pictures. right ?

[@amanial-khalifa5299]

Excellent. Thank you!

[@Marimari-ev6rr]

I have my physics exam in a fee hours and I'm just watching this rn , lovely , but thank you sir for explaining everything in such a superb way !

[@AutumnInsane123]

it would be good if you can explain in further details of the use of the materials alongside with the description of the x-ray tube , e.g.why is tungsten used. Just a suggestion to your future videos (maybe?)

[@DarkLevis]

Very very nice video But why high energy photons penetrate body but low frequenzy ones not?

[@TheBassHeavy]

Very well explained! Thank you!

[@nadalcathe3436]

No i searched for linear attenuation coefficient for X-ray but didn't get what I was looking for. But with attenuation coefficient i got it on wikipedia. Thanks Sir.

[@twchen0402]

I am sort of confused. So the braking radiation and inner shell electron transition are two different mechanisms. The latter is the usual way to generate x-ray. Right? and does the electron acceleration inside the CRT(cathode ray tube) create some long-wavelength x-ray or just the ultra-violet radiation ?

[@Spirit-Consciousness]

Aweeeeeeeeeeeesomeeeeeeeeeeeeeeeeee videeoooooo .... u r the best physics teacher :) (y) subscribed..!

[@aliciaroye7236]

Hi, Thanks for all your wonderful videos, been a big help in simplifying some topics in Physics. Do you have any lessons on the Inverse Square law? Thanks! Keep up the good work.

[@xxxreptilianxxx]

This is really useful! This is also GCSE physics by the way, you may choose to change the key terms so others can find it!

[@lifesnotstill5003]

hardly.....

[@xxxreptilianxxx]

adil m It's in my syllabus?

[@lifesnotstill5003]

James Lavender what board?

[@lifesnotstill5003]

By hardly I mean that in GCSE there is hardly any depth.

[@xxxreptilianxxx]

Edexcel, and I agree- although it is easier to answer a question when you understand something rather than just knowing that it happens.

[@jasonbellamy9759]

This is fantastic - thank you so much!!!!!

[@bostaphkatya]

Excellent! thank you so much for your explanation!

[@akshatasurati5448]

Precise and perfect

[@shakirbaba6765]

Best explanation.. love it

[@zatulmutalif3230]

sir how do we know whether the x ray image produces a good contrast??the question that i did, the answer talk about the ratio of I°/I but i dont understand...

[@Montymylie1]

Is ionisation when the x-rays are made and exitation when the are the body?

[@rucksapps]

Tungsten has a high electron density and, when hit by the electrons coming from the cathode, emits a characteristic x-ray, in that the waves have a high enough frequency and therefore, enough energy to penetrate the aluminium plate covering the tube and thus, enough energy to penetrate the bone etc to reach the lead (less penetrable material to absorb the photons)...

[@cusshoe]

Excellent video...

[@kevinmun1]

Sir, I would like to ask.Like what you mentioned, high speed electron will hit the electron from the tungsten atom. And then the outer electron will jump into the inner shell to replace it. Energy lost is the X-Ray. After outer electron fall into the inner shell, The more outer electron, I mean will others electron replace the jumping electron? will X -ray produce also?

[@nas_kabir]

Dear DrPhysicsA, this is a great presentation. But something worrying me ,The lead gratings at 17.00, will also be shown in the Films? that will obstruct with the image of interest. ? kindly clarify

[@suppandi1000]

The lead gratings are long but sufficiently thin

[@FakeDeath02]

This was very helpful thanks for the video

[@Cait09here]

Hi Thank you very much for your videos they are absolutely brilliant you explain things so well. I need to know what ionisation and excitation mean for my exam and from what I have gathered from your video because only 1% of electrons hitting the anode are converted into x-rays and 99% heat up the anode is this due to excitation and ionisation? Any help would be greatly appreciated :)

[@drsheikh]

Excellent commentary.

[@elvisokon7554]

sir please can you do more of cie? that would be helpful

[@emu98391]

You did a nice job! I think it will be help to review this when I study.

[@hamnachaudhary4657]

You explained really well.

[@themrworf1701]

Thanks! You explained a lot!

[@stervi2]

What would happen if an incident electron didn't make a head on collision with one of the tungsten electrons but got very close? would it excite the tungsten electron and that would then emit a photon when it falls back down to its original energy level? if so, would it emit x-rays?

[@aal-dahir1773]

Help with a question sir Does changing intensity, changing penetration and changing voltage affect the x-ray spectrum?

[@reshamregmi272]

Thank you very much DrPhysicsA. It was very beneficial for me to learn physics in conceptual way. I think it would have been better if we can get your video in HD too.

[@Chiko-sc1gz]

14:18 isnt that area supposed to be WHITE if no electrons reach the plate?

[@weakwok3550]

why the electron accelerates round the nucleus release x-ray photon?

[@MsSergey1313]

A excellent lesson! Thank you!

[@Missamytta]

Awesome explanation! Thank you :)

[@YaduPoudel]

Thank you. Your voice is amazing

[@confusion3146]

I just have a few questions, does the rotor part of the anode also rotate along with the disc? Which part of the mechanism actually controls the tube current, is it the tube part of the cathode or the thermionic filament? Also, the anode is the positive part but does this refer specifically to the disc of the anode or the rotor that's positive to attract the electrons?

[@rustyjeanz]

+DrPhysicsA Dear Dr. I got one question. At 14:00 why you draw the X Rays emerging from Anode not straight lines but around 15:00 you draw straight lines that are emerging from anode. Is this because the samples are bone and soft tissues respectively? If yes , but how do the X Rays know whats the sample. So Can you explain both cases considering the same straight lines emerging? Thanks

[@dvdmine]

Is there a reason we use tungsten as the anode?

[@marcus00077]

Wow. Great job.

[@soliltary]

Thnx for providing knowledge to people like us

[@rustyjeanz]

very nicely explained. Thanks a lot :)

[@hartwiggrant4263]

I like this video, it helps a lot. Good Job, thanks...

[@eljay1402]

Dear Dr Eagle, just a quick (probably very simple) question. When the electrons accelerate past the tungsten atoms, why do they give out energy? Thanks so much.

[@DrPhysicsA]

When electrons speed past tungsten atoms they may travel very close to the nucleus, which of course is heavily positively charged. That will cause the electrons to change direction because they are attracted to that large positive charge. This means they are subject to an acceleration. Accelerating charged particles give off radiation. That is essentially what happens in a television transmitter. Electrons are accelerated up and down the transmitter and emit television waves. In the case of tungsten however the change in energy is sufficient to generate x-rays.

[@coldpatrician]

+DrPhysicsA also known as the slingshot affect.. they are attracted enough to gain speed but not to just hit the nucleus. if im not wrong.

[@shaneellal1086]

This is very useful, thank you.

[@housseinmasri7704]

I want to know,how I can prevent cutoff?

[@biajidejajchowdhury1058]

Thank you professor, it's a great lecture.

[@samb18_kite]

what happens to the electron when it delivers all its energy to radiation. zero kinetic energy implies it comes to a stop. But how is that possible?