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# Modulating a dc current

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#### Wagaloo

##### New Member
Hi, i am learning electronic, and i can't figure that one out.

I know that "when a fluctuating electric current flow through a wire, it generates a magnetic field", is the reverse true. Can you use a magnetic field to modulate an electric current. If it's the case, can i use this in a circuit with a constant load like a class A amplifier?

I'll appreciate if you could help, thanks.

Can you use a magnetic field to modulate an electric current.
Yes, that's how transformers work.
But to do it in a single wire generally requires a large magnetic field for even just a small voltage deviation (the current deviation from this voltage depends upon the resistance of the wire and its load).

Can you use a magnetic field to modulate an electric current.
It's also how generators work. They use a steam power (or a gas engine) to turn a giant rotor with magnets on it and the magnets move past coils of wire which produces current in the wire.

magnets move past coils of wire which produces current in the wire.
Technically it produces voltage.
The current depends upon the impedance (load) of the wire.
Thus a generator with no load still produces voltage, but no current.

Technically it produces voltage.
The current depends upon the impedance (load) of the wire.
Thus a generator with no load still produces voltage, but no current.
Yeah, but I chose to say current so as not to confuse the OP since that's the way he phrased it and there seems to be a language barrier.

Yeah, but I chose to say current so as not to confuse the OP since that's the way he phrased it and there seems to be a language barrier.
Okay.
But I think it's better to be technically correct than to be concerned about a possible language barrier or confusing the OP.
If the OP doesn't learn the correct terms, then he will continue to perpetrate his incorrect understanding.

Okay.
But I think it's better to be technically correct than to be concerned about a possible language barrier or confusing the OP.
If the OP doesn't learn the correct terms, then he will continue to perpetrate his incorrect understanding.
My leniency varies from day to day depending on how charitable I'm feeling

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Magnetic tape heads and dynamic microphones are other examples where a changing magnetic field produces electrical changes.

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