How fast do CRTs shoot electrons?

[Ralphonsicus]

Thanks.

 

[zahero_2007]

It must be less than the speed of light.

 

[Ralphonsicus]

Yes I know that because electrons have mass and therefore (according to special relativity) they cannot reach light speed. But that wasn't the question, the question was HOW FAST do CRTs shoot electrons (on average)?

 

[QuantumPion]

Yes I know that because electrons have mass and therefore (according to special relativity) they cannot reach light speed. But that wasn't the question, the question was HOW FAST do CRTs shoot electrons (on average)?

With a quick bit of googling I found that the voltage of a CRT TV cathode is 400 V. Therefore an electron accelerated will obtain 400 eV of energy. The speed of an 400 eV electron is 1.18*10^7 m/s or ~4% of the speed of light.

 

[Hepth]

In a large tube-TV the accelerating voltage the electron feels is about 25,000 Volts, so a rough non-relativistic approximation says that will be about 1/3 the speed of light.

http://hypertextbook.com/facts/2000/MichelleHong.shtml

 

[QuantumPion]

Oops, don't know how I came up with 400 V. Maybe that's for a ye olde oscilloscope or something.

 

[Ralphonsicus]

Haha it's grand, thanks all.