why does a loud speaker not produce sound when direct current is passed through?

  • 0 votes

why does a loud speaker not produce sound when direct current is passed through?

its a question in the gcse, aqa kerboodle textbook! it would be appreciated if someone could help me!

thankyou

<3

Posted Sun 2nd December, 2012 @ 10:46 by elllieeeeeeeee

6 Answers

  • 2 votes

well according to my knowledge, a loud speaker has a coil of wire is suspended in a magnetic field towards the top, behind this is a permanent magnet surrounded by other magnets, alternating current moves back and forth through the coil of wire and since its in a magnetic field, the current causes the other magnets to vibrate, pushing and pulling against this fixed magnet, this causes the coil to move back and forth, if you used direct current, then it could only go one way and not back and forth.

if you did not understand some of this, it is pretty complicated, then you can look at this website with an animation to show it in actrion.

http://electronics.howstuffworks.com/speaker6.htm

hope I helped :D

Answered Sun 2nd December, 2012 @ 11:00 by Eamon Walker
  • 2 votes

A revised version, you have a coil of wire above a permanent magnet, the aternating current goes from positive to negative through alternating current, as is attracted then repeled from the premanent magnet, this causes it to move back and forth, also the permanent magnet is surrounded by vibrators which help produce sound.

Answered Sun 2nd December, 2012 @ 11:07 by Eamon Walker
  • 0 votes

thankyou so much Eamon Walker!!!! that does make really sense, you're really good at explaining!! aaah yeah as it is a direct current it couldnt go back and forth which that motion creates the diaphragm to vibrate in which sound waves are created! so it wouldnt produce sound! thankyou you've been great help!

<3

Answered Sun 2nd December, 2012 @ 11:14 by elllieeeeeeeee
  • 0 votes

no problem.

Answered Sun 2nd December, 2012 @ 12:22 by Eamon Walker
  • 0 votes

To be honest, I am actually grateful I help people on this site as it gives me the chance to look things up and see how they work!

Answered Sun 2nd December, 2012 @ 12:23 by Eamon Walker
  • 0 votes

Direct current is just on so the coyl of wire is just pushed out at the start but if you put a pulsing current in to it at every rising the coil is pushed out but on the falling edge the coyl is pulled in and its this occilation witch produces sound the frequanncy. the duty cycle (in PWM only), the amplatude and the wave length have an efect on the sound produced 

Answered Wed 5th December, 2012 @ 12:46 by daniel austin