Electron Gun - Backstage Science

[funnyhead222]

4:00 "what is vacuum?"

you'd expect anyone who's walking in that room to already know what a vacuum is lol

[doggie1kitten]

now make a molecular accelerator and put inside JUSTIN BIEBER

[srosefx]

how wonderful it is to be talked to like an intelligent being, i didnt understand all of that, but thats okay big network tv stations, i will use my brain & ill figure it out myself

[OKMUNWURX]

The cathode would need to be at a negative voltage for this to work.

[jag9998]

SUPER FASCINATING ಠ_ಠ

[chilidress]

if i take the electron gun of a crt can i make an accelerator?electron gun is used in x-ray photographs?

[butterfingers8008]

Are there any other uses for an electron gun other than particle accelerators?

[douro20]

That's a pretty far cry from the much simpler thermionic electron gun which is used in small LINACs and cathode ray tubes.

[guitarer99]

Dick at 1:32

[theofficialstig]

I love your enthusiasm and ability to explain complicated things in a simple way by the way at 4:51 you seem so happy with your job that you are almost laughing

[theofficialstig]

I love your rnthusiadm and ability to explai things in a simple way btw at 4:51 y

[Swiftynine]

HOW DOES MAGNETS WORK? (:

Love the Video (:

[kibabiba]

1 man was gun down

[lexichronicle2]

My physics lecturer described the photoelectrons as being emitted instantaneously when the photons impacted the surface. I asked, "so does that mean they share characteristics of the original beam like coherences or wavelength if it's instantaneous?", she answered "I don't know, I'm not sure why you'd need that." I suggested it may be useful for accelerators. Can Lee shed any light on this? Pun most definitely intended.

[MrDannyArcher]

I regret taking add math :(

but Im GLAD I took physics :D

[anonysquirrel]

I presume the polarity of the high voltage at the cathode is negative relative to the anode at ground potential. After electrons pass through the hole in the anode, do they continue on their trajectory without any positive potential drawing them forward?

[culwin]

Awesome, I have now begun working on my own electron gun!

I figure I will have a complete particle accelerator complete by June.

[JeanKM1]

Some people seem to be asking you to make longer videos. Please don't do that. I subscribe to a lot of creative commons channels, but I rarely have the time to watch them. The length of your videos is just perfect.

[Nigel705]

Ahh mounted inside a vacuum bowl! I get it now.

[aCagedApe]

what happens when you pass your hand through the electron beam?

[Tommiclio]

@aCagedApe At a guess, I'm gonna say it might hurt! 300,000 volts .... lol

[youtubasoarus]

Absolutely fascinating! This is the kind of stuff that turns regular joes to go to school and become involved with this type of thing.

[metadaptation]

hey, great video! Quick question, does the laser that starts the electrons moving from the cathode use the same principle as the way that the photons cause electron ejection in the photoelectric effect?

[Matulite]

"Once it's gone through the hole my job as a gun physicist is done"

[huntingvuk]

very cool you make great videos! thanks,

[BackstageScience]

@huntingvuk thank you!

[brenoakiy]

about the laser part, does that have anything to do with the photoelectric effect?

[jeebersjumpincryst]

@brenoakiy photoelectric emission, its called. some materials (also selenium,caesium,lithium) can release electrons merely by exposing it to light. Exposure meters used in cameras use this effect. I really wish he had explained a whole lot more, about a whole lot more things. I know Brady is on a time limit, but Lee could at least aim it a little more on the comlex end, imo. Thanks for another great vid tho guys. Always appreciated :)

[brenoakiy]

@jeebersjumpincryst so basically, the laser (photons) gives an extra "boost" to the electron emission

xD

[jeebersjumpincryst]

@brenoakiy Im not sure, to be honest, but wish he had explained it. Usually (tv's etc)electrons are produced by thermionic emission,which is a heated up filament(often tungsten)which produces a 'space cloud' of electrons.these dont go anywhere until a large potential dif is applied between the filament and an anode.he refers to it here as electric field.sounds like his one works in 'reverse'. a pd is applied first, then a laser is used to trigger a big torrent of electrons in a very short time.

[jeebersjumpincryst]

@brenoakiy Though if you have the time, I'm sure wikipaedia or somewhere online could tell you all about it. Dont take what I've said as fact - it's all I could remember, and I had to look in a book here to refresh (yes, a BOOK!) Check everything for yourself.

[madjimms]

Galium Arsenide, when will you be part of my CPU?

[Carutsu]

@BackstageScience don't you have google partnership!?

[rapturecase]

why is there a picture of a guy painted on the cathode?

[G3org3Master]

@rapturecase Its called a reflection.

[LamaPaj]

@rapturecase

LOLOLOLOLOLOLOLOLOOOOOOLOLOLOO­OO

[TeoSims]

@rapturecase he took the picture duuuuh

[Busterlanger1]

@rapturecase 'tard

[Probewitch]

Wow; glad I don't have that power supply just to operate my old television.

[defect530]

thumbs up if you think im a douche bag for saying thumbs up :D

[bazanar]

@5:01 Thumbs up for the ninja guard :P

Joke aside I love the channel. thanx!!!

[steffenml]

This channel should seriously be mandatory for any science teacher to subscribe to, if for nothing else then at least to be able to bring up a selection of videos to add to their "further reading"-curriculum.

[9hello123]

@steffenml Why?

These videos are very interesting, but there's nothing in them that anyone studying any of the sciences wouldn't know, they're designed for the general public not science students, anyone past GCSE should already know everything in these videos to a much greater depth understanding the math behind it.

There's a reason these videos don't ever mention any maths or equations, they aren't designed for science students.

[BackstageScience]

@9hello123 they might know the maths, but have they ever SEEN an electron gun and someone who makes them?

That's what I like about making these videos... It's the stuff I learned at school, but suddenly it's real and in someone's hand!!!

From my experience on other projects (like periodicvideos, etc) this is what makes a handful of students go from "okay I understand the maths" to saying "actually I could do that as a career!"

And for everyone else, it's just cool to see it!

Just my opinion.

[9hello123]

@BackstageScience Like I said I find the videos very interesting and I watch them all the time, but if a science teacher started showing their students these videos, the majority of students that would enjoy watching videos like this probably already do, and the majority students that don't already watch videos like this would just be uninterested and not learn anything.

[9hello123]

@9hello123 Don't think I'm saying these videos are bad, I love them, just that anyone that does want to see videos like this already will, its not like they're some hidden secret.

[frohman101]

Too bad you didn't tell us about all the details of the device, I study chemistry and would likely have understand it :(

[Timei]

Very intriguing

[MadMacheart]

i regret not taking physics ;(

[BackstageScience]

@MadMacheart it's never too late!

[flyingpigstuff]

@MadMacheart I am 40, mopping floors ATM just to attend Uni again.

[DeanMalenko]

I wonder if this is (in a less sophisticated way) how the old cathod ray tube monitors/TVs work

[LechuCzechu]

@DeanMalenko Yes, that's EXACTLY how it works. Moreover - "electron gun" is the first particle accelerator that humans bulit.

[DeanMalenko]

@LechuCzechu thanks, I wasn't entirely sure if they would build high end equipment like this into simple TVs, so I thought it must be different in a way, much like you can have steel forks and plastic forks, they both do the same thing but one is cheaper material

[LechuCzechu]

@DeanMalenko Well, actually in a CRT TV-set or PC screen, the cathode is not excited with laser but with glowing fillament (like in a light bulb).

Actually it is a typical, single-stage Liniac - elecrons are accelerated by electric field between cathode and anode. Not only CRT work like this - also old vacuum tubes (aka thermonic valves).