Dynamics of charged particles and quantum effects

[manofphysics]

Why do we not consider quantum effects when we deal with motion of electrons in a Cathode Ray Oscilloscope, or in a cyclotron?
We derive various relations using classical physics which turn out to be quite accurate in the laboratory.How is this possible when it is expressly known that classical physics fails when analyzing the motion of isolated particles of atomic size like elctrons?
[ for eg. F=qE => ma=qE and thus accn. of the chargedparticle is found.This should NOT work in case of an electron due to unceratinity principle]

[ZapperZ]

Why do we not consider quantum effects when we deal with motion of electrons in a Cathode Ray Oscilloscope, or in a cyclotron?
We derive various relations using classical physics which turn out to be quite accurate in the laboratory.How is this possible when it is expressly known that classical physics fails when analyzing the motion of isolated particles of atomic size like elctrons?
[ for eg. F=qE => ma=qE and thus accn. of the chargedparticle is found.This should NOT work in case of an electron due to unceratinity principle]

Other than space-charge effects, there are no electron-electron correlations involved in such a situation (meaning, no significant wavefunction overlap, etc).

While you certainly CAN evoke QM formalism (if you're a glutton for punishment), you can get practically all the relevant effects simply via classical equations. In fact, classical E&M work pretty darn well under such circumstances. One only needs to look at the description for charged beam dynamics in particle accelerators. Numerical codes being used to track particles in a particle accelerator, such as PARMELA, PIC, etc. are all based on classical mechanics.

Zz.

[manofphysics]

Thanks a lot, Zz.