What is the difference between magnetism and electromagnetism?

[mohsin3069]

what is the difference b/w magnetism and electromagnetism

 

[mohsin_kiet]

magnetism

Electromagnetism is produced by current through a conductor.An electromagnetic field exists only when there is current .
A magnetic field exists independently of current

 

[hussain_kiet]

Re: magnetism

electromagnetism is a phenomenon caused by the flow of current through any conductive coil...
while magnetism is caused by a simple permanent magnet...!!!!

also check out these links
https://en.wikipedia.org/wiki/Electromagnetism
https://en.wikipedia.org/wiki/Magnetic_field

 

[suvendu]

magnetism

Magnetism induced by electricity is called electromagnetism.

 

[mateuko]

Re: magnetism

Hi,
Only suvendu has touched the heart of this problem... Electromagnetism is NOT a magnetism induced by current flow!
Let's start form the beginning.
When somebody is saying 'electricity' he should mean 'electric field' . When somebody's saying 'magnetism' he's surely thinking about magnetic fields.
The source of electic field are static charges.
The source of (only) magnetic field is constant movement of charges, for example electrons in a wire (when electron accelerates it's emittig electromagnetic wave.)
Unless we have high values of acceleration of charges, we do not need to worry about depedency between electic field and magnetic field. We can assume that magnetic and electric fields are existing separately. When we have high values of such acceleration (which is often caused by high frequency AC current) the electric and magnetic fields are unseparable, it means that the (fast) change of electric field induces magnetic field and the (fast) change of magnetic field induces electric field. This phenomenon was founded by James Clerk Maxwell. His famous 'Maxwell's equations' are in deed a form of already known equations, but nobody earlier couldn't see the strong depedency between two of them. For this observation Maxwell got a Nobel prize.

So, when we are saying 'electromagnetic field' we are thinking about fields raised by AC current. If frequency is low (50Hz) we can simplify problem and say 'magnetic field' because induced electric field by a change of magnetic field is very, very low. But if the frequency is high (>= ~100kHz) we have situation described above and we have to say 'electromagnetic field".

 

[Meridian]

magnetism

Good answer Mateuko!