Cathode Ray Tube Experiment and Charge To Mass Ratio of an Electron

This chemistry and physics video tutorial provides a basic introduction into the cathode ray tube experiment. JJ Thompson used this experiment to conclude that all atoms contain negatively charged particles known as electrons. Using this experiment, he was able to calculate the charge to mass ratio of an electron.
Chemistry - Basic Introduction:
• Chemistry
Scientific Notation Review:
• Scientific Notation - ...
Significant Figures Review:
• Significant Figures - ...
Unit Conversion Problems:
• Converting Units With ...
Accuracy and Precision:
• Accuracy and Precision
Density Practice Problems:
• Density Practice Problems
________________________________
Pure Substances & Mixtures:
• Pure Substances and Mi...
Homogeneous & Heterogeneous Mixtures:
• Homogeneous and Hetero...
Physical and Chemical Changes:
• Physical and Chemical ...
Solids, Liquids, Gases, & Plasma:
• States of Matter - Sol...
Physical Vs Chemical Properties:
• Physical vs Chemical P...
__________________________________
Law of Conservation of Mass:
• Law of Conservation of...
Law of Definite Proportions:
• Law of Definite Propor...
Law of Multiple Proportions:
• Law of Multiple Propor...
Rutherford's Gold Foil Experiment:
• Rutherford's Gold Foil...
Cathode Ray Tube Experiment:
• Cathode Ray Tube Exper...
_________________________________
Atoms - Basic Introduction:
• Atoms - Basic Introduc...
Cations and Anions Explained:
• Cations and Anions Exp...
Diatomic Elements & Molecules:
• Diatomic Elements & Mo...
Elements, Atoms, & Molecules:
• Elements, Atoms, Molec...
Protons, Neutrons, & Electrons:
• How To Calculate The N...
_______________________________
Final Exams and Video Playlists:
www.video-tuto...
Full-Length Videos and Worksheets:
/ collections

[@TheOrganicChemistryTutor]

Final Exams and Video Playlists: www.video-tutor.net/ Full-Length Math & Science Videos: www.patreon.com/mathsciencetutor/collections

[@niroshanaperera7330]

3 boring hours of brain-melt from my teacher, condensed into 18 interesting minutes of knowledge. Thank you so much.

[@nijamuddinsarker9139]

I wish to meet u one day brother...

[@lacquishalakk5859]

Mee toooooooooo

[@nickkal6397]

Please forgive him bro

[@varunsathya1912]

This sounds like a threat

[@wonderman8537]

@@varunsathya1912 note he called him a brother

[@Jinan_ad]

I am him😂

[@whoisanjaia]

He lost me when he started talking abt Physics

[@TonyG-n1m]

You mean when the video started?

[@m.fatihturkoglu1848]

Why is this so simple when you are explaning it man omg like every one of your videos like that i love youuuu

[@farahrasheed1536]

dude what a coincidence I took this today at school and I didn't understand anything but now it looks easy for me thank you so much

[@manarahmed4952]

Saame!

[@aizadzulqarnaen6655]

I got online class about this last week and tbh i don't even remember a thing

[@imanadil5849]

kinda upset that this was posted after my exam :(

[@saadextremist8104]

Brother you helped me immensely with this. I was so troubled, my textbook showed the e/m value without even a hint about how it came to be.

[@AbbasKhan-me1gi]

why did he use right hand rule, he was supposed to use left hand rule for getting the direction of the force. Right hand is used for the direction of induced current, innit?

[@elisabettanatuzzi4287]

I can only say: “thank you”.

[@ohayogozaimasusensei5551]

16:56 Why is the electron moving in the upward direction considering the force for negative charge is downward. Shouldn't it move in a circle in the downward? Or I missed smth?

[@patrickfiset1694]

I too have this question.

[@patrickfiset1694]

My answer gets deleted, so I'll try once more in next comment

[@patrickfiset1694]

He applies the material once the electric and magnetic force are balanced. Then the electron are affected by the magnetic force, and (I think) CIRCLES starting downward. But maybe the circle-motion, being perpendicular, have nothing to do with the curve going up, so I think the magnetic force, the only force left, attracts the electron to the north plate that might be a positively-charged material.

[@sciencenerd7639]

Finally, a video that gives a complete explanation of this experiment! Thanks.

[@rock24039]

Please make a video on how to follow your videos to complete organic chemistry topic wise.

[@mohamedkanneh9608]

Cathode rays tube are a stream of negatively charged particles (corpuscles) later know as electrons how does it happen.

[@user-wi3lg1rz8f]

Hi i think there is a little mistake at the end where u show the Experiment by Thomson. The B field should direct the electron to the down side not the upside after it left the E field. 16:40 Thanks for the great explanation ✌️

[@al-aehel7766]

-NOTE-1 How did jj Thomson know that the ray consist from negative charge? 4:23 1)Due to the fact that it was deflect towards the positively charged plate 2)the fact that all different materials can emit a cathode ray helped him conclude that all atoms(materials) contain negatively charade particles -NOTE-2 Q= why is the ray green glow ? Bc the chamber is coated with a phosphor materials known as zinc-sulfide so when the electrons strike the glass they creat this characteristic green glow -NOTE-3 Describe the experiment Inside an evacuated chamber The prussue is very very low Also we have cathode (negativly chared electrod) and Anod (positivly chard electrod) Next When the caothod is heated by any heating element And if there a high voltage applied between c and a An electron beam is going to emanate (from the c towards the a and the a accelerate the ray towards the right)

[@markle3303]

my chem teacher explained this to me for a whole 75 minutes class and I didn't understand anything. You explained it in just a few minutes and I finally got it, you are my chem savior!!

[@tracymokeira9528]

Wait which country are you from? Because in our country this is under physics subject

[@SathvikArunSulakhe]

​@tracymokeira9528 Doesn't it come under both Physics and Chemistry? In my country it comes under both

[@ambikanath2918]

Tysm u r such a good teacher u r doing an awesome job

[@bamideledavid3372]

This guy has a video on EVERYTHING Physics and Chemistry

[@philoso377]

Nice video and presentation. Page 3:40 acknowledging that charge plate affect the beam from moving straight. But wouldn’t the glass tube wall blocks electric field of the plate? If not why not?

[@georgesadler7830]

Professor Organic Chemistry Tutor, thank you for a solid analysis of the classical Cathode Ray Tube Experiment and the Charge to Mass Ratio of an Electron in AP/General Chemistry. The Cathode Ray Tube Experiment is a well-known experiment in Science and Engineering. This is error free video/lecture on KZbin TV with the Organic Chemistry Tutor.

[@philoso377]

Page 5:00 I didn’t notice that the experiment test with insulation materials other than various metals, how can we conclude all materials possess and can emits electrons?

[@naveensingh5787]

the electron source was metal plates or ionisation of gas taken in the tube?

[@JamieDiseker]

This is why Tesla never got his death ray built. I guarantee it has something to do with getting the death built, just saying I was the first to say the cathode ray / Death Ray.....might have had some technical similar condition

[@m3rvat]

i have question In cathode ray experiment there was used an electric field, so how was it determined which metal is + or - charged if the charge is determined by electrons and it wasn't yet discovered same goes with the voltage before discovring elctrons how was it determined which + or -

[@skywalkeRRRR893]

U teach better than my irl teacher

[@kasra38s]

*than all of the viewers, otherwise, we wouldn’t be here! :)

[@bebrownbear8354]

I dont understand why Fm can make cathode ray opposite Fe?

[@lililili8411]

Thanks for giving such clear explanations on the calcus !

[@rishi7573]

I want to meet you in person you have the answers to all my problems I wish I could give you something

[@paulhetherington3854]

Hence; create special - LED leads - tits - console. And it's all, video game intel.

[@LauraBenezia-XIIPA]

Thank you very much, this video really helped me for facing my exam

[@rabihk6872]

At 7:07 shouldnt the magnetic force exerted on the electron be downwards instead of upwards? Using RHR, taking your thumb to the right and your fingers outwards( toward you) , the palm of your hand will be facing downwards( the magnetic force).

[@MegaGiannisz]

So two questions I can't seem to get an answer to. Firstly, how was he able to realise which plate is positively and which was negatively charged since those values until deeper levels (quantum physics) are purely arbitrary. Secondly, since the direction of the magnetic field does not change direction how does the electron move in a circle? What am I not understanding here? It is clear to me that velocity changes direction so the x product of v and B will have a different value. And intuitively as well, shouldnt the ray be deflected until its velocity is only towards the z axis? How does the magnetic force keep it's centripetal character even though the magnetic field is uniform in a single direction?

[@fatimalearns9618]

Did you get an answer to your questions?

[@ashrayakochara2291]

yes im so confused about the whole anode cathode thing

[@JSvideos576]

One thing he glosses over is that the equation is actually F=qv x B. The magnetic field produces a Lorentz force that is perpendicular to both the velocity vector and the magnetic field. It only reduces to qvB when the cross product is 1 (angle is 90 degrees so sin(theta)=1, and B field is perpendicular to velocity). As the particle changes direction the uniform magnetic field is still constantly producing a force perpendicular to the velocity vector. In this case it's the same concept as centripetal force. For circular motion with uniform velocity the force is perpendicular and toward the center of the circle. So I guess for the second question, yes the magnetic field is not changing direction, but the force is because the particle is changing direction and this is built in to the equation with the cross product.

[@JSvideos576]

I see what you are saying now, as you already mentioned the cross product. For it to make sense you really have to visualize this in 3 dimensions. Otherwise, you might come to the conclusion that deflection would stop at a certain point. The particle is never moving in the same direction as the magnetic field since they are in completely different planes.

[@shipurmohammed4764]

JJ THOMPSON

[@Aaron-ji2yg]

nice video its help me alot on chemistry :)

[@chancetshimanga3727]

not all heroes wear capes 👑

[@DeptaGoOn]

Thank you for your clarification. This has unlocked my brain from freezing.

[@tanhrs8711]

Why is the trajectory a circle and not a parabola ?

[@williamscott1516]

Bc the (magnetic) force is perpendicular to the electron's velocity (right hand rule). I'm guessing your confused bc idk for example if you throw a ball (constant grav force) its trajectory is parabolic, thing is tho, if you were to yeet a ball fast enough that 1 the gravitational force is perpendicular to its motion and 2 it stays perpendicular to its motion, it would also be a circular trajectory. (I think)

[@tanhrs8711]

​@@williamscott1516thank you for the explaining. It was actually very clear !

[@allyhanaffy2329]

i want to ask something. is this experiment electrolytic or galvanic cell? sorry, if I ask a dumb question.

[@Aminhelal210]

You made me actually love science I am so grateful

[@gayatrid2748]

How do we calculate radius of curvature?

[@mr.unwonted4947]

It's so good and specially in simple words, I am a Physics student and I'm learning it for my Modern Physics part

[@shwethashetty306]

In14.38 thumb should be at left as we take current on opp direction. To flow of electron

[@ollymclure2143]

This rule is for moving particles in magnetic field. Your thumb points in the direction of the moving particle regardless of charge. Just remember when you do this with a positive charge the force comes out of your palm but withe a negative charge it comes out the back of your hand.

[@science-y9209]

Yup youre right..

[@192ali1]

Excellent demonstration. what happens if positive and negative terminals of the battery were swapped?

[@ayaaymankhttab]

Thanks for teaching me what my teachers in egypt failed to.

[@mponchanok]

Thank you so much!!

[@jullietlamina2125]

Nice video❤️. Can you please make a video for the oil drop experiment

[@losvegas2569]

for some reason, ur voice is healing

[@Alex-gg9ht]

How?

[@Debbie-wg1ht]

I love you so much, I do not know what I would do without you😭

[@juniorcyans2988]

I learned from my professor how to use right hand rule to find the direction of F, B, and v. I struggled a while as you arranged y and x arises differently. Finally I realized that what I learned is still right.

[@sefalibhakat143]

Why cathod ray not collide with the anode???

[@tanishqkhurana8721]

Anode tube had a hole in it

[@yuvrajkhater2227]

It’s perforated

[@dr.basmaelhamali9269]

Could you please explain CRO cathode Ray oscilloscope....it would be really helpful ..thanks

[@shwethashetty306]

Thanks man but how do you cAlculate magnetic force

[@nellvincervantes3223]

Magnetic force = charge* cross product of velocity and magnetic field

[@eunicekibui4472]

This is completely awesome. thanks ❤uuuuu

[@joefanningartist]

Does this mean that also using this experiment, one could conclude which is the positive and negative side of a magnet?

[@josephquaye937]

God richly bless you. Wish to meet you one day.

[@deceit0223]

Good explanation.....my teacher doesn't know how to teach......thank you for your service....may good things come to you....bless you

[@Alex-gg9ht]

You have skill issue, get good 🤓

[@reg3250]

Excuse me professor may I go to the comfort room?

[@AvaMaina]

use better grafix

[@araatasunts5366]

At least ! The best video about the kathod ray experiment ! The author is awsome !!!

[@RoyHoy]

Que?

[@emekaekwuedivinesomtochukwu]

I must confess that this video is loaded 💯👏👏

[@adityakailash8391]

If there is more pressure in the tube I theorise it would be fine because electrons are subatomic particles they can pass through gas particles in the tube

[@yjstylz2673]

No bro , the reason why pressure is this low is that there can't be any other gas particles left otherwise u won't any fine beam emanating from cathode . Moreover, any subatomic particle can't just pass through another atom whether they are matter-particle fermions or force-carriers bosons .

[@AsuwalkLfeti]

See another

[@ryanchen2341]

i love you dad, pls come back

[@samalger3336]

Hey dude how does r^2=q/m

[@samblehhhhh]

I see

[@fadeyibimayowa1021]

Master you're amazing, you're a God sent

[@IsaacAwad.04]

How many subs dies he was ?

[@qwerty0202]

In ncert text deflection of electron in the presence of B is given just opposite?

[@ruiiios]

????

[@judyimali6677]

What about the grid system

[@DANIELDALLAS_MATHs]

If U mean about Grid as a third electrode that carries the duty of handle the electron stream, there is no a single word about. But you can apply superposition principle to figure out the effect it has on the stream

[@harrig2403]

you sound like mark wahlberg

[@fantulemma]

respect JJ Thomson

[@عبدالرقيبالحنشلي]

Thank you so much you are the best

[@nhatduong1534]

Mass of electron should be 9.11*10^-31kg

[@georgesadler7830]

He converted the mass of an electron to grams which is correct.

[@henrikl...1264]

Very good thank you

[@JohnSm3847]

Thank you

[@arsei8389]

6:51 I've been struggling with the directions of the magnetic field, magnetic force, and velocity of the charge for two weeks and it turns out that I was using the direction of velocity of a positive charge while studying about ELECTRONS😐🥲

[@philopateerzaki5016]

About how much I love u ❤

[@henrykoufie9142]

Good job 👏

[@THEIMRANACADEMY]

⭐⭐⭐⭐⭐⭐

[@sadhusaisrujan3031]

Super

[@evabunnik9635]

This has been so helpful thank you!!!!!

[@adamraiyan]

Thank you !

[@annikavashist448]

How is it that the since the magnetic force provides the centripetal force, it's equal?

[@vikrantsingh4504]

because the magnetic force is a centripetal force i.e. the centripetal force on its own is not a force(centripetal force is not a part of four fundamental forces it is a category fo forces which acts in a circular way)

[@averagedoggosenjoyer2897]

@@vikrantsingh4504 +1

[@sagemaster3408]

Because the magnetic force IS the centripetal force. Basically the magnetic force causes the centripetal. Therefore it’s equal. Remember that “centripetal force “ is basically explaining what the original force is doing So if the original force is the magnet Therefore, the centripetal would have same value .

[@Arnal_2075]

Class 11th students 😢

[@stoneddayandnight]

12th wala hun bhai, Structure of toms and Nuclei mein padhega yahi same cheez tu, isliye atomic structure par dhyaan de.

[@Arnal_2075]

@@stoneddayandnight ok bhai thank u

[@kasra38s]

You’re a hero 😍❤️❤️❤️

[@jordanfindlay625]

Life saver

[@nachiketnalamati564]

Thank you 😭

[@navieats3955]

dope

[@heaven3706]

thank you!!!

[@camilamolina499]

What exactly is an electrode?

[@Vedant.Dhawan]

U dumb

[@kasra38s]

@@Vedant.Dhawan 😒😒

[@Vedant.Dhawan]

@@kasra38s what?

[@kasra38s]

@@Vedant.Dhawan don’t be toxic

[@ajricherson1099]

According to the right hand rule, shouldn't the force at 8:26 be directed downward? Is it opposite because the electron has a negative charge?

[@ajricherson1099]

Nvm, I looked in my physics book, and it is indeed flipped because of the negative charge.

[@teresamartins9277]

​@@ajricherson1099explain plzzzz

[@Eclipse-qo9pw]

I don’t know why in the world are people using right hand thumb rule for this we would not apply RHR because it gives the direction in which the particle would deviate due to electric field but we need to find the direction of deviation due to magnetic field for a moving charge so we will use the LHR