Electron Diffraction Tube

In this video, produced by the National STEM Learning Centre and Network and the Institute of Physics, Alom Shaha explains the elements of an electron diffraction tube and how to use one to demonstrate a diffraction pattern. The video is aimed at teachers but it could also be used with older students to illustrate the working of an electron diffraction tube.

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Stuart Billington

Very clear and concise, with good tips on safety.

Where can I buy the EHT with built in voltmeter and separate switches?! Mine don't have either. And the shrouded plug leads, too?

Jenifer Burden

Dear Stuart

Glad you've found these films useful, thanks for the feedback. I've checked with Alom Shaha, who worked on the films and is presenting this one, and a suitable example product is the Edu-Lab EHT supply (Rapid Electronics are one source of this, rapidonline.com). I'll do some more research and add any other suggestions here.

Best wishes


Great stuff - will be a great help to schools who have this kit gathering dust in cupboards. A follow up film on the even more useful fine beam tube would be great to see.


Superb video. Tried to set this up myself for the first time a few weeks back and didn't have much success. No problem when I tried it after watching this. Clear, concise and well explained.


Brilliant! Another really cool way of getting the point across! A magnet, why not? It would be interesting to have the same diffraction pattern from a laser beam through a pin hole next to the tube and show the magnet doesn't affect the path of the light! Not sure if you mentioned it in the video (I was reading a tweet in that bit, sorry).

Carol Davenport

I used the video with non-specialist teachers. Very useful - especially the sensible safety advice.


Thankyou for a wonderful set of concise and clear instructions.
As a non-physics technician I found them easy to follow and I'm proud to say I got it working first time.

Jenifer Burden

Very pleased to hear this worked well for you. If there are other demonstrations that you would find it helpful to have shown as a video then we'd like to know, via resources@nationalstemcentre.org.uk.


I really like this! Our School used to have an EHT Voltage supply unit just like this one!!! And I loved demonstrating cathode rays with the apparatus! Alas! The unit is broken!! It's great to have this video to show to my students now! Another great classroom asset!


Great video. You can make this quantitative for your students by measuring the distance of the first fringe from the centre and divide by the target-screen distance to get an angle. They can then calculate the spacing of the carbon atoms. They'll need some scaffolding; eg they need to work out the speed of the electrons from the accelerating voltage; then calculate the De Broglie wavelength and use the diffraction equation.