Aboutcleggsan Expertise All technical areas of Electronics Engineering.
Experience BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.
Organizations IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.
QUESTION: Hi there,
Thanks in advance for reading this question. It may seem a little strange. I have a hypothetical situation I would like to get some advice/info on.
Let's say I have an electromagnet connected to 20 wires. When I switch on the electromagnet, obviously all 20 of the wires become magnetized. Is there any way/any technology I can add into the equation to control which wires are magnetized and which wires remain un-magnetized? I want to be able to choose specific wires to magnetize while still having all wires connected to the electromagnet. Is this impossible? Is there anything I can use to make this possible?
ANSWER: Let's go back to the beginning about electromagnets.
The magnetic field is created when current passes through the coil wrapped around the iron material (if an iron core is being used; or could be open air). The magnetic field does not exist if there is no complete circuit for current to pass through the wire coil.
You can use several coils, each with its own drive circuit to create at magnetic field an operate each one independently if that is what you are wanting to do.
Hope this helps you better understand how an electromagnet works.
C
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QUESTION: Hi, thanks very much for your answer. I did not explain myself well because I am not so familiar with electromagnets I guess.
If I connect the drive circuit to a piece of metal, and connect that piece of metal to a number of wires (as I have sketched in the image attached) I am assuming the piece of metal and the wires will all be magnetized when the electromagnet is activated, would that be correct?
Unfortunately I cannot use several coils to create magnetic fields independently as you suggested. My project is on a very small scale and there is not enough space for a number of electromagnets. I am looking for a way to magnetize a number of wires using one electromagnet (or a small number of electromagnets). I am wondering if there is any way at all to control which of the wires attached to the piece of metal which is attached to the circuit drive become magnetized. Am I searching for something that is impossible?
In the picture I have included a box called Object 1. If this box was something like a semiconductor, and the wires being magnetized all ran through it, could the semiconductor control which wires are magnetized and which aren`t?
Apologies for my shocking lack of knowledge and thanks again
Answer Let me go back to the beginning again. Wires do not become magnetized (since they are usually a non-magnetic material such as copper). What does happen is that when current is passed through a circuit the current in the wire produces a magnetic field. The magnetic field encompasses the wire. So, you must have a complete circuit with a battery or power source which will cause current to be conducted through the circuit.
In your diagram there are no completed circuits, hence not current will flow in the wires, hence no magnetic field will be produced.
Ohms Law: Voltage = Current X Resistance. If there is no voltage there would be no current; of the resistance if infinite (no conducting path) there can be no current. Thus, no magnetic field can be produced.
Electronic switching from one circuit to another is possible, but if there is no circuit to switch there is no need for the switching mechanism.
In the diagram which you sent back the magnetic field is produced around the iron core by a battery connected to the two terminals of the coil. When the battery is connected current flows through the coil producing a concentrated magnetic field in the air surrounding the iron core.
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