Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Speaker Magnets
Name: Rose Mally
Status: Other
Age: 40s
Location: N/A
Country: N/A
Date: N/A


Question:
SINCE A SPEAKER HAS A MAGNET ON THE BACK OF IT, WOULD IT HARM THE SPEAKER OR THE DEVICE CONNECTED TO THE SPEAKER, IF THE SPEAKER WERE TO BE MOUNTED BY THIS MAGNET? FOR INSTANCE ADHERING THE SPEAKER THE THE REFRIDGERATOR WITHOUT BENIFIT OF SPEAKER BOX?

THANK YOU I HOPE YOU CAN HELP ME,
ROSE MALLY



Replies:
No. The speaker magnet is there to provide a permanent magnetic field for the the speaker coil, which is embedded in the paper of the speaker cone. When the audio signal flows throw the speaker coil it generates a small magnetic field the strength of which varies with the strength of the audio signal. This small magnetic field is repelled by or attracted to the permanent magnetic field produced by the speaker magnet. Thus the paper cone moves away from or closer towards the back of the speaker. Hence as the strength of the audio signal wiggles the paper cone wiggles back and forth, and you get sound waves that match the audio signal.

Only the field in front of the speaker magnet (where the speaker cone is located) is of any use. The field that comes out the back of the magnet serves no purpose, and you might as well use it to stick the speaker to the fridge.

Grayce


No, this won't harm the speaker or anything connected to it. However, removing the speaker from its box will change the sound it produces. The speaker will no longer be able to produce low-frequency sound because the air pushed from the front of the speaker will be able to leak around the speaker to the back (which of course is pulling air whenever the front is pushing it). So the speaker will not be able to produce any substantial change in air pressure at low frequencies, and thus you won't hear low frequencies from it.

There's a lot of science in a speaker box, and generally a speaker is designed to work with a particular sort of box: vented or not vented; if not vented, then the volume of air in the box is important; if vented, then the vent is effectively a tuned pipe, and the size and resonant frequency of the vent is important. In both cases, sound reflected from the back of the box affects the motion of the speaker cone.

Tim Mooney


No. The speaker magnet is there to provide a permanent magnetic field for the the speaker coil, which is embedded in the paper of the speaker cone. When the audio signal flows throw the speaker coil it generates a small magnetic field the strength of which varies with the strength of the audio signal. This small magnetic field is repelled by or attracted to the permanent magnetic field produced by the speaker magnet. Thus the paper cone moves away from or closer towards the back of the speaker. Hence as the strength of the audio signal wiggles the paper cone wiggles back and forth, and you get sound waves that match the audio signal.

Only the field in front of the speaker magnet (where the speaker cone is located) is of any use. The field that comes out the back of the magnet serves no purpose, and you might as well use it to stick the speaker to the fridge.

Grayce



Click here to return to the Engineering Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory