# Basic electronics theory (response to Layman's issues)

Discussion in 'Architecture & Engineering' started by billvon, Nov 18, 2014.

1. ### LaymanTotally Internally ReflectedValued Senior Member

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The only part I seem to be struggling with is explaining something in a way that would make you happy that wouldn't distract from the point I was trying to make. Now, that we got that taken care of, it would mean that the electrostatic force from the permanent magnets would attract to the magnetic force of the inductors.

An example would be creating an electromagnet by winding a wire around a screw driver attached to a power source, and then that would attract metal and magnets just like a normal magnet would.

3. ### billvonValued Senior Member

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Again, no. If you do not exceed the threshold voltage the transistor stays off.
Again, no. You missed the base resistor. The base junction of an NPN transistor remains at about .6 volts in operation. The current is what matters - and the base resistor turns the voltage difference into a current. (Ohm's law would be helpful here.)
If that happened the transistor would be destroyed.
Again, basic bipolar transistor theory would help here. Or just look at a data sheet for an NPN transistor - particularly the performance curves.

5. ### TrippyALEA IACTA ESTStaff Member

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CORRECT!! YOU'RE GETTING IT!!

It's still not going to attract or repel the positively charged plate of a capacitor though, like you suggested here:
Back in Post #70

As long as we're clear that Capacitors store electric fields, and inductors store magnetic fields...

DING DING DING! CORRECT AGAIN, THAT'S TWO OUT OF TWO, TELL HIM WHAT HE'S WON BOB!!

But no matter how many windings you use, and how much current you put through those windings it's still not going to attract a piece of amber, not matter how much silk you rub it with or how hard or how fast you rub it.

7. ### Aqueous Idflat Earth skepticValued Senior Member

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Incorrect. Misapplication of cite; wrong cite. Look up "electrostatic force".
Electromagnetic radiation is a form of energy, not force. There is no such thing as "electromagnetic force". There are electric and magnetic forces, static and dynamic. Here you are confusing waves and fields.

And no, you are still missing the point: Compare Coulomb's Law to Biot-Savart. They are not the same.

Last edited: Nov 23, 2014
8. ### LaymanTotally Internally ReflectedValued Senior Member

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Finally, I can pick up from where I left off in the other thread, before I was so rudely interrupted. The electrostatic force from the permanent magnets would create a voltage level or charge in the inductors and lines of the circuit. Note, this would not create power to generate a magnetic field from the inductors, but it would create a voltage level across the circuit that could replace the power source. This could activate the hall sensor. If the hall sensor is active it could activate the transistors. This would allow the voltage level created from the magnets to be different from ground separated by components. This would allow for current to flow to ground, creating current. Then with a path to ground opened up to the inductors, current would flow across the inductors. This would then create a magnetic force from the inductors. Then operation of the circuit could occur without a power source, but it would require very strong magnets likes the ones used in the video that look like they came from inside a disk drive. I would like to try it but I don't have 4 disk drives I could dismantle for the components.

9. ### TrippyALEA IACTA ESTStaff Member

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BZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZTTTTTT!

There is no electrostatic force created by the permanent magnets!!!!!!

10. ### LaymanTotally Internally ReflectedValued Senior Member

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Your really giving me a bad headache. The magnet would attract electrons just like a positive power source would.

The End.

11. ### Aqueous Idflat Earth skepticValued Senior Member

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For the umpteenth time: you need an external power supply to energize the coils. You are failing high school science here, to say otherwise. You are proposing to violate conservation of energy.

12. ### TrippyALEA IACTA ESTStaff Member

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It's you're not your.

There are no moving electrons and no moving magnetic fields in the setup, so there is no current.

Take a moment to think about what you're saying - according to your logic you'd never be able to switch the motor off.

13. ### Aqueous Idflat Earth skepticValued Senior Member

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The magnetic field does not "attract electrons". It deflects moving electrons, as in a CRT, which is different. In every case you need an external power supply.

14. ### TrippyALEA IACTA ESTStaff Member

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This is why we have the requirement, from Faradays law, that you need a rotating magnetic field to make an electric motor work.

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/farlaw.html#c1

15. ### LaymanTotally Internally ReflectedValued Senior Member

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If you had a wire floating in mid air suspended there would be no current. Then it would take a moving magnetic field. If you had a wire tied to a resistor heading to ground, then you put a electromagnetic field on the other side of the resistor, it would create a difference in voltage between each side of the resistors. A difference in voltage would create current flow.

All voltage represents is the difference in charge between two points. When there is a difference in charge, current or the electrons flow from negative to positive.
The difference in an electrostatic field and a magnetic field don't seem to be self consistent in the way you describe it. A permanent magnet operates because the dipole moment is in one direction. In a lot of ways, it would be the same as the electrostatic field created by a capacitor. If you moved a dielectric plate that is charged down a wire, it would generate current. Then it doesn't have to move to create a voltage. Voltage can slowly transfer from one plate to the next. In a way, the permanent magnet would just be acting like a dielectric plate.

16. ### LaymanTotally Internally ReflectedValued Senior Member

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"Any change in the magnetic environment of a coil of wire will cause a voltage (emf) to be "induced" in the coil. No matter how the change is produced, the voltage will be generated."

Interesting link... At least someone out there seems to understand what I am saying.

17. ### LaymanTotally Internally ReflectedValued Senior Member

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All I am saying is that the power source is equivalent to the electromagnetic force created by a magnet. The difference in voltage from ground would allow for current flow. In a lot of ways, a battery just operates by having a difference in voltage levels of each side. The electromagnetic force is generated by having a difference in voltage of each side of the object creating a dipole moment.

18. ### billvonValued Senior Member

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No; they are fundamentally different. For example, there are no "point sources" in magnetic fields as there are in electric fields.
No, it wouldn't. Again, they are fundamentally different. Maxwell's Equations explains this.

19. ### billvonValued Senior Member

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No, that creates an electric field, not a magnetic field. They are not created the same way nor do they act the same way. They are different.

20. ### LaymanTotally Internally ReflectedValued Senior Member

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I don't really see why you think this, the power supply would always supply a constant voltage as well. Then it can be turned off when this constant voltage is applied.

21. ### LaymanTotally Internally ReflectedValued Senior Member

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Then this link fails to describe it in terms of power. Just because it wouldn't create power doesn't mean it wouldn't create voltage. For example, a charged capacitor would create a voltage level on the other side of it. It wouldn't create current flow on the other side of it unless it was tied to ground. Then the capacitor could be discharged. If the other side of the capacitor wasn't tied to ground, then the other side of the capacitor would just maintain a constant voltage level.

22. ### RandwolfIgnorance killed the catValued Senior Member

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Wow Layman, you're taking a real likkin' here and trying to keep on tickin'...

23. ### TrippyALEA IACTA ESTStaff Member

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Correct.

Incorrect. If you take a wire with a resistor and ground it, then no matter how bright the torch is you're not going to induce a current in that wire simply by shining light on it.

Incorrect. Voltage is measured in Joules per coulomb, it is the amount of energy in joules carried by each coulomb of electricity.

Seperation of charges causes a potenital difference. You do work to seperate the charges and impart energy to them in doing so. This potential difference is what makes a current flow.

Only because your understanding is flawed.

'Dipole moment' describes a vector, it has a direction and a magnitude. In the case of a magnetic dipole moment, it describes the strength and direction of the magnetic field.
A magnetic domain is a region within a piece of ferromagnetic material where the magnetic moments of individual atoms are aligned.
Permanent magnets are permanent magnets because the entire body of the magnet is one magnetic domain.
Magnets can have multiple magnetic domains, however, this weakens the magnets.
Finally, this is why heating a magnet above its curie temperature works to destroy its properties - because it randomizes the alignment of the atoms leading to the spontaneous formation of many small domains.
This is also how magnetizing a needle works.
This is sometimes called a magnetostatic field.

Correct, but for the wrong reasons - the electric field doesn't induce a current directly (above and beyond those created through charging) the moving charge creates a magnetic field which in turn induces currents.

Voltage is the amount of energy carried by each unit of charge. The charge does not have to be moving to have energy, this is how capacitors work, lightning works, and electrostatic charges in general work. The charged surface creates an electric field, which can in turn induce other electric fields without the involvement of a magnetic field.

No. I repeat. It doesn't matter how hard and fast you rub that piece of amber, it's never going to be attracted to or repelled from a magnet.