# What are the behaviours of beams of protons, neutrons and electrons in both electric and magnetic fields?

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Electrons and protons have equal but opposite electrical charges. When they move, they create a small circular magnetic field that is normal to the direction of their motion. When they move in an electric, and or a magnetic field, the particles move in a direction determined by the vector sum of the various forces caused by the interacting fields.

Free protons move towards the more negative end of the electric field;
Free electrons move towards the more positive end of the electric field;
The motion in each case will be essentially parabolic ( ignoring disturbances due to other forces ). Bound protons and electrons will simply be displaced.
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Free protons and electrons, in motion in a magnetic field, tend to follow a helical path (ignoring disturbances due to other forces). For protons and electrons moving in the same average direction in a magnetic field, the helical displacement will be clockwise in the case of one of the charged particles and anticlockwise in the case of the other.
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Neutrons are electrically neutral and are not deflected by electric or magnetic fields.
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Best wishes - Majikthise.
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I have calculated that the deflection of the electrons while passing through the region between the plates is 0.014 m. This is correct, same answer as the answer key.
To calculate the size of the deflection as seen on the screen, I would say that
D/0.014 = (20+6) / 6
as there are similar triangles
D/0.014 = (20+3) / 3
Why does it only take half of the length of the charged plate to do this proportionality between similar triangles and not the whole side?
I know that the deflection is not significant until it reaches maybe half the plate. Is this the reason why it only takes half?
Any help really, really, greatly appreciated.