would it be poss able to direct a static charge using a magnetic field in a vacuum?

Question

i.e. if a partical was posatively charged and another was negatively charged and both were contained in a magnetc field(like gravity) then can you direct its energy as means of propultion: kind of like equal and oposite : in a vacuum

Answer 1

Yes. The device is called an ion drive and can be used to propel a spacecraft. An element is evaporated, ionized to acquire a positive charge, and accelerated by electric and/or magnetic fields to expel the ions; separately, electrons are expelled to keep the spacecraft electrically neutral. The process can provide acceleration for a long time (high "specific impulse") but the thrust produced is very low, so such a craft must first be placed in space by other means (e.g. chemical rockets).

Answer 2

Pechorin is technically correct, however, what you are asking is exactly how a television picture tube works. They are also called cathode ray tubes (CRT), and there is a man-made vacuum in them.

The cathode is a hot filament, much like a light bulb filament that glows when current is forced through it. As it gets hot, electrons boil off of it. If there were no other charge applied, they would just cloud around the cathode, repelling one another and gradually spreading out in a 'space charge'.

There is a coating on the inner side of the tube, where it expands, just behind the screen. This is charged to a very high positive voltage (ten to twenty thousand volts.) This attracts the electons and gets them streaming toward the inner side of the screen.

There are beam-shaping electrodes (think of a charged washer, or funnel) through which the electrons pass. These are negatively charged, so the moving electrons are repelled by them. At the same time, they are so strongly attracted to the positive high voltage, that they force their way through the little hole in the middle of the beam-shaping electode. The electrons come out in a needle-fine beam.

So far, all we have talked about is electrostatic repulsion and attraction. Now comes the magnetism part. There are two sets of coils wrapped around the neck of the CRT. Currents flow in these coils and form changng magnetic fields which move the electron beam back and forth. (Think of a strong wind blowing the stream from a water hose.)

There are two of these magnetic fields. One increases linearly to a maximum value, and then drops almost instantly back to zero. This field moves the beam horizontally. If nothing else was happening, it would cause the beam to move in a horizontal line across the screen.

The other magnetic field moves the beam vertically. If there was no horizontal deflection, this would cause the beam to move in a straight line up and down the screen.

What happens is the beam is 'steered' . It is raised to the top left of the screen, swept across the screen, dropped down a little bit, swept across again, then dropped down a little more. This keeps repeating until the entire screen has been covered and the beam windw up inthe lower righthand corner of the screen. Then the whole process repeats. Think of spray painting and you will get the idea. This happens very rapidly, many times every second.

In the meantime, the beam from the cathode is turned on and off many times, very rapidly.

The inside of the screen is coated with a chemical called phosphor, which glows when it is hit by the electron beam. There are different kinds of phsophors for different colors, but I will only deal with on and off for light or dark, here.

When the beam is on, and it is steered to a particular spot on the screen, the electrons hit the phosphors and cause them to glow, for just a very short instant. Then the electrons have given up most of their momentum to the screen. They bounce back off of it, and are still attracted by the high voltage on the inner side of the wide part of the tube. They are absorbed into the conductive coating and flow back into the rest of the circuit. Fresh electrons take their place.

So, what we see-- is a series of rapidly drawn still pictiures, which our minds interpret as moving. Whenever an electron hits the screen, it produces light. When the beam is turned off, it is dark. The magnetic fields are constantly sweeping out the same pattern, so that the picture appears in the same place.

(Of course, things can go wrong; I am speaking about the ideal condition. When you see the picture or text go rolling vertically, that means that the vertical sweep is not synchronized properly, and when the picture or text goes rolling horizontally, that mans that the horizontal sweep is not synchronized properly.)

I have said nothing about how the tv camera makes its picture, or how the keyboard makes the leters, but those are separate questions. I hope this tells you what you want to know. If you are intersted, try looking up articles on television cameras and transmission. Color tv adds a whole new dimension of complexity to this, so I will not get into it here. But this was an excellent question!

Answer 3

I don't think its practicle as a means of propulsion, but thats how the lenses of an electronmicroscope work. Also CRTs Cathode ray tubes except for there the final collision of the electron is with a phosphor which emits luminescence or light which we see. you need a lot of power for a very small out put

Answer 4

Static charges are unaffected by magnetic fields. You would first have to accelerate the charge.

Answer 5

All the time- this is the principle operating technique of vacuum tubes, and picture tubes

Yes, look up "Ion Engines" as propulsion

Answer 6

Ummm yeah... that's what they do all day at particle accelerators.

Answer 7

Well it would not be static once it was moving, so no.