I Slowing down a moving electric charge

AI Thread Summary
To slow down a moving electric charge, an electrical force is necessary since magnetic force acts perpendicular to velocity and does not reduce speed. While magnetic forces can change the direction of velocity, they cannot decrease its magnitude, which is essential for slowing down. The discussion emphasizes the importance of considering power, as it is the scalar product of force and velocity that determines energy transfer. Infinitesimal displacement is mentioned, but the focus remains on the vector nature of velocity. Ultimately, only an electrical force can effectively slow down an electric charge.
Alex Schaller
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If an electric charge q is moving with a certain velocity v and we want to slow it down, this can only be done with an electrical force because magnetic force is perpendicular to displacement, correct? (watch video, time stamp 0:42)
video
 
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Yes. Although i see no video.
 
weirdoguy said:
Yes. Although i see no video.
It was only a pop video after all!
 
Yes, I am thankful for whatever made it disappear.

Anyways, I wanted to write something in my first post, but I didn't, so I'll add it in this one, so that it's not completly useless:

Alex Schaller said:
force is perpendicular to displacement

This is true, but since this displacement is infinitesimal, I think that it is better to think in terms of velocity. Force is perpendicular to velocity at every instant, so it does not transfer energy, since it's power (scalar product of force and velocity) is zero. In general, keeping track of powers is easier than works done by forces.

I don't like infinitesimals.
 
The velocity of an electric charge is a vector quantity and it can be changed by a magnetic force.
 
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The direction can be changed. OP talked about slowing down, which means readucing magnitude of velocity, which can't be done by magnetic field.
 

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Thread 'Applying the Gauss (1835) formula for force between 2 parallel DC currents'

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Please can anyone either:- (1) point me to a derivation of the perpendicular force (Fy) between two very long parallel wires carrying steady currents utilising the formula of Gauss for the force F along the line r between 2 charges? Or alternatively (2) point out where I have gone wrong in my method? I am having problems with calculating the direction and magnitude of the force as expected from modern (Biot-Savart-Maxwell-Lorentz) formula. Here is my method and results so far:- This...
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