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Magnets [message #75550] Sun, 17 February 2013 21:59 Go to next message
Sonicsound is currently offline  Sonicsound
Messages: 59
Registered: July 2012
Location: United States
Baron
When I was a kid, my father would always dissect broken things and save some of the parts. One thing that I remember is how he would always save the magnets in speakers. I never thought to ask, until now when I am making a homemade compass, why are there magnets in speakers? What purpose do magnets have in sound?
Re: Magnets [message #75568 is a reply to message #75550] Tue, 19 February 2013 20:12 Go to previous messageGo to next message
Kenwoody is currently offline  Kenwoody
Messages: 105
Registered: February 2013
Location: United States
Viscount
Magnets are used to create alternating current within the speaker. The positive ions in one magnet are attracted to the negative polarity in the other magnet and vice-versa. When the ions move back and forth between the magnets, it creates electricity. There's a HowStuffWorks on it that might explain it a little better than I can.
Re: Magnets [message #75573 is a reply to message #75568] Wed, 20 February 2013 09:33 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18782
Registered: January 2001
Illuminati (33rd Degree)

Actually, a speaker transforms electrical energy to kinetic energy using the interaction of two magnets. One is a fixed magnet and the other is an electromagnet. Back several years ago, they used to make speakers with two electromagnets, one that was energized with a stable direct current, and the other fed the audio signal, which is an alternating current waveform. In either case - field oil or fixed magnet - the result is the same, which is that the audio signal causes movement of the cone because of the interaction of the fixed magnet with the one fed with the audio signal. Your "HowStuffWorks" link shows this pretty well.

What you described is the reverse, and that's pretty much how microphones work. The sound moves the diaphragm, and that in turn moves the coil. The magnet flux cuts across the moving coil and this creates a current, which is the audio signal.

Re: Magnets [message #75616 is a reply to message #75573] Fri, 22 February 2013 20:43 Go to previous messageGo to next message
Kenwoody is currently offline  Kenwoody
Messages: 105
Registered: February 2013
Location: United States
Viscount
Well I knew I was describing something that had to do with sound, ha ha! Laughing I remember my dad explaining speakers and mics to me as a kid and I guess I got the two mixed up! That was also the same conversation where he explained the purpose of magnets in generators and alternators in cars... (I was absolutely fascinated by magnets as a kid.)
Re: Magnets [message #75633 is a reply to message #75550] Mon, 25 February 2013 05:33 Go to previous messageGo to next message
Sonicsound is currently offline  Sonicsound
Messages: 59
Registered: July 2012
Location: United States
Baron
I'm learning I probably should have paid more attention in physical science class! I totally forgot about a lot of the stuff you are talking about, but I will experiment with these things somehow and in some way. I just need to find a project I can do using two magnets.
Re: Magnets [message #75635 is a reply to message #75550] Mon, 25 February 2013 07:18 Go to previous messageGo to next message
Chicken is currently offline  Chicken
Messages: 300
Registered: August 2011
Grand Master
Sonicsound, they never touched much on the practical applications of moving magnets (like mics and speakers) when I took physics in high school. It's a shame; I would've paid more attention if they had. Laughing
Re: Magnets [message #75636 is a reply to message #75635] Mon, 25 February 2013 17:16 Go to previous message
Kenwoody is currently offline  Kenwoody
Messages: 105
Registered: February 2013
Location: United States
Viscount
Chicken wrote on Mon, 25 February 2013 07:18
Sonicsound, they never touched much on the practical applications of moving magnets (like mics and speakers) when I took physics in high school. It's a shame; I would've paid more attention if they had. Laughing


I know, right!! I would have paid a lot more attention, too. I didn't learn about magnets and electromagnetism until I took up an interest in cars and my dad explained their role in making cars run...
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