Why Transformers Hum? | Unpaired Electrons & Magnetic Fields

[PanCerowany]

Why transformers hum?

I have heard two versions. Oxygen has unpaired electrons and it reacts to changing magnetic field. Material that transformer is made of vibrates in changing magnetic field.

Both explanations tell that something vibrates in a magnetic field, but what it is?

 

[uart]

It is caused by magnetostriction.

See : http://en.wikipedia.org/wiki/Magnetostriction

 

[torquil]

Why transformers hum?

I have heard two versions. Oxygen has unpaired electrons and it reacts to changing magnetic field. Material that transformer is made of vibrates in changing magnetic field.

Both explanations tell that something vibrates in a magnetic field, but what it is?

The second one is correct. It is called magnetostriction. The varying magnetic field inside the transformer influences the metal:

http://www.federalpacific.com/university/transnoise/chapter2.html
http://www.federalpacific.com/university/transnoise/transnoise.html

It is also possible that the windings themselves move around a bit from the forces acting on them.

Torquil

 

[sophiecentaur]

Why transformers hum?

Maybe because they don't know the words?
Boom Boom

 

[Phrak]

Magneto restiction?

 

[sumit sawai]

2nd one is correct it is called as magnetostriction
core material in transfprmer is feromagnetic in changing magnetic field of transformer there is slight change in shape of material which causes vibration
which produce huming noice

 

[PanCerowany]

OK, thanks.

 

[PanCerowany]

lol, www.electrical-riddles.com[/url] vs [PLAIN]www.electric-gibberish.info - obviosuly more sense in riddles than in gibberish