e/m Electron (Charge to mass ration for the electron) + MATHS - F-J's Physics - Video 133

[@enkiorenlil]

is it circular or is it spiraling? at 05:05

[@AnthonyFrancisJones]

Good question. To be honest with you, if things are not well lined up the path will be slightly helical possibly with a spread to the beam's width. To work well it needs to have a very carefully lined up magnetic field that is also very uniform in strength. You do the best you can with the Helmholtz coils!

[@tuopeeks]

Nice experiment. This is one tube I don't have. Now wondering the partial vacuum impacts the speed of the electron, for the given accelerating voltage, perhaps adding to the error. However, seeing the electron travelling path is definitely part of the wow factor with this tube.

[@AnthonyFrancisJones]

Yes, it's a lovely tube and again and experiment that must not be lost in time for pupils. I hope teachers will still know how to do it. It is important that the technicians are trained well too as the days of the physics technician (single subject) who was at the school when your father was are all but gone! I have been lucky to work with some younger technicians who lap this stuff up, which is great! Yes there will be some scattering of the beam due to the ionisation collisions but, at this pressure not much variation I feel. It is a good tube to have in your collection as it is capable of lots of different experiments. I am always impressed with what you can both demonstrate and determine in a school laboratory!

[@gertvalve729]

I have the same kind of tube with Helmholtz coils. Is the anode voltage 150?

[@AnthonyFrancisJones]

Yes, 150V is about right. The manual suggests no more than 30mA allowing for voltages from about 120V to 300V. Remember this is one of the tubes that does not use EHT!

[@gertvalve729]

@@AnthonyFrancisJones Thank you for the answer.

[@AnthonyFrancisJones]

@@gertvalve729 Pleasure!