My first thought was, Who doesn't know how to make an electromagnet but as you said, it is good to go over the simple stuff again. I find watching something I already know about , a thought-provoking exercise that sometimes yields a new thought, maybe in another direction. Almost confused myself. 🙂 Anyhow, thanks for the video.
Glad you liked it! I totally get "Who doesn't know how to make an electromagnet" and I was debating if this should be combined with the (soon to come) permanent magnet and demagnetizing videos which are a bit more in depth.
I know this video is aimed at the introductory level but I was wondering if you could give me some insight into the diminishing returns experienced due to coil resistance. When winding a coil for a large electromagnetic with a target amp turns of say 3000 the resistance of the enameled wire gets to the point that you require a thicker gauge drawing more current and producing more heat. How do you optimise an electromagnet to have the highest possible flux density before saturation with the lowest wattage.
That's a great question! The things that come into play include a) the number of layers of the winding needed to create the desired number of turns - the outer turns use greater length of wire and have more resistance and b) the resistance of the wire which is proportional to 1/ the diameter squared of the wire (and also the diameter limits the number of turns on each winding layer). You could set up some equations to see how changing wire size alters things like required voltage, power consumed etc, but lets do a bit of hand waving: Lets assume we only have one winding layer so number of layers does not add to the complexity. We start with 1 turn of wire and that length of wire has a resistance of 1 ohm. So with 1V applied we get 1 Amp and 1 amp-turn. If we do two turns of the same wire, we now have 2 ohms of resistance, and with 1V applied we get 0.5 Amps and 0.5A x 2 turns = 1 amp-turn. So assuming the power supply can always supply enough current, the wire size that sets the amp turns that are generated, and the more more turns you have, the less power and current you need for a given number of amp turns = field strength. Adding winding layers to accommodate more turns add more resistance per turn and begins to reduce the resulting current and hence amp turns for a given voltage. How great this effect is depends on the relative length of windings on inner and outer windings. The smaller the inner winding's diameter in relation to the wire diameter, the more pronounced the effect is. So in general, for a DC electromagnet, the more windings you have, the less power needed for a given amp turns. Hope that helps!
Doesn't making the current double back along its original path cancel out the field it established on the way out? I daresay you could get a much better result by twisting the two conductors together at both ends and applying current to the opposite ends.
Guess I didnt explain it well - connecting the one side's white wire with the not-white wire at the other end of the coil turns the two wires into one loge wire with twice as many turns. I could have pulled the wires apart and spliced them together into a long single wire before winding them to have the same effect but more work. As a general rule, the more turns the better!
Funny you said that - it took me back to my childhood too which made it fun!. What I find neat is doing those experiments again with the insight of years of electromagnetics education and experience making them so much more meaningful.
Sounds a bit like energy harvesting. If you have a diode in series with a coil (one or more loops), the coil will pick up some energy from RF fields given off by the cell phone and the diode will rectify them. No idea why a zener diode would be used unless there is an issue with too high a voltage near the phone which is unlikely. Look up crystal radio which essentially is the same thing.
@@elarcadenoah9000 How neat! So the diode is a switching diode but does seem limited to a few hundred mhz based on the spec sheet I looked at so its surprising that it works with phones with transmit frequencies generally greater than 700Mhz. It is close to the phone so it could be picking up energy from the switching power supplies or something else operating at lower frequencies. Would be interesting to see if its the loop or the "antennas" from the wire leads is picking up the energy. If its the loop, a single diode might be better. I'll have to try it sometime.
@@ElectromagneticVideos i can give u a page where a guide also experiment with magnetic detector also ghost detects i think is his pasion and lighting detectors so u can see many of his experiments but u maust insist he give a link for his shematics some of them are difusse ruclips.net/video/k9Rx4x0BePk/видео.html
@@ElectromagneticVideos this kid has also detector for cell phones also if they are disconected and the zenner diode i send u before i thisnk he uses for radiant energy free energy and i think is possible
It should! May depend on how much non-magnetic regular sand material forms part of each grain. If too much, the magnetic attraction may be so weak its not noticeable.
My first thought was, Who doesn't know how to make an electromagnet but as you said, it is good to go over the simple stuff again. I find watching something I already know about , a thought-provoking exercise that sometimes yields a new thought, maybe in another direction. Almost confused myself. 🙂 Anyhow, thanks for the video.
Glad you liked it! I totally get "Who doesn't know how to make an electromagnet" and I was debating if this should be combined with the (soon to come) permanent magnet and demagnetizing videos which are a bit more in depth.
I know this video is aimed at the introductory level but I was wondering if you could give me some insight into the diminishing returns experienced due to coil resistance. When winding a coil for a large electromagnetic with a target amp turns of say 3000 the resistance of the enameled wire gets to the point that you require a thicker gauge drawing more current and producing more heat. How do you optimise an electromagnet to have the highest possible flux density before saturation with the lowest wattage.
That's a great question! The things that come into play include a) the number of layers of the winding needed to create the desired number of turns - the outer turns use greater length of wire and have more resistance and b) the resistance of the wire which is proportional to 1/ the diameter squared of the wire (and also the diameter limits the number of turns on each winding layer).
You could set up some equations to see how changing wire size alters things like required voltage, power consumed etc, but lets do a bit of hand waving:
Lets assume we only have one winding layer so number of layers does not add to the complexity. We start with 1 turn of wire and that length of wire has a resistance of 1 ohm. So with 1V applied we get 1 Amp and 1 amp-turn. If we do two turns of the same wire, we now have 2 ohms of resistance, and with 1V applied we get 0.5 Amps and 0.5A x 2 turns = 1 amp-turn. So assuming the power supply can always supply enough current, the wire size that sets the amp turns that are generated, and the more more turns you have, the less power and current you need for a given number of amp turns = field strength.
Adding winding layers to accommodate more turns add more resistance per turn and begins to reduce the resulting current and hence amp turns for a given voltage. How great this effect is depends on the relative length of windings on inner and outer windings. The smaller the inner winding's diameter in relation to the wire diameter, the more pronounced the effect is.
So in general, for a DC electromagnet, the more windings you have, the less power needed for a given amp turns.
Hope that helps!
Doesn't making the current double back along its original path cancel out the field it established on the way out? I daresay you could get a much better result by twisting the two conductors together at both ends and applying current to the opposite ends.
Guess I didnt explain it well - connecting the one side's white wire with the not-white wire at the other end of the coil turns the two wires into one loge wire with twice as many turns. I could have pulled the wires apart and spliced them together into a long single wire before winding them to have the same effect but more work. As a general rule, the more turns the better!
You take me back to my childhood!
I have found that those clamps are pretty bad and have several ohms of resistance...
Funny you said that - it took me back to my childhood too which made it fun!. What I find neat is doing those experiments again with the insight of years of electromagnetics education and experience making them so much more meaningful.
Great video! I enjoyed it. Thanks for sharing!
As always, your welcome!
🌐
:)
good video
Thanks Peter!
i saw a video of some zenner diodes in serie that can detect magnetic current from a cell phone, can u explain us how is that possible?
Sounds a bit like energy harvesting. If you have a diode in series with a coil (one or more loops), the coil will pick up some energy from RF fields given off by the cell phone and the diode will rectify them. No idea why a zener diode would be used unless there is an issue with too high a voltage near the phone which is unlikely. Look up crystal radio which essentially is the same thing.
@@ElectromagneticVideosi found the video so u can see by yourself ruclips.net/user/shortsbGeJJ0p3La8
@@elarcadenoah9000 How neat! So the diode is a switching diode but does seem limited to a few hundred mhz based on the spec sheet I looked at so its surprising that it works with phones with transmit frequencies generally greater than 700Mhz. It is close to the phone so it could be picking up energy from the switching power supplies or something else operating at lower frequencies. Would be interesting to see if its the loop or the "antennas" from the wire leads is picking up the energy. If its the loop, a single diode might be better. I'll have to try it sometime.
@@ElectromagneticVideos i can give u a page where a guide also experiment with magnetic detector also ghost detects i think is his pasion and lighting detectors so u can see many of his experiments but u maust insist he give a link for his shematics some of them are difusse ruclips.net/video/k9Rx4x0BePk/видео.html
@@ElectromagneticVideos this kid has also detector for cell phones also if they are disconected and the zenner diode i send u before i thisnk he uses for radiant energy free energy and i think is possible
can electromagnet attract iron sand? fe203/magnetite
It should! May depend on how much non-magnetic regular sand material forms part of each grain. If too much, the magnetic attraction may be so weak its not noticeable.