Question

Examples where C-EMF can be generated?

Hi,


Do you know systems that generate C-EMF?
Set ups like an Electric Motor? What other system do you have in mind?

Another thing.
I know that CEMF is caused by a changing electromagnetic field. How can an electromagnetic field be changed? Please elaborate!

Answer 1

you just need a changing magnetic field..

faraday laws says that a changing magnetic field (more precisely magnetic flux) induces an EMF .. so that can be done in a numerous ways

the magnetic flux that is linked with any coil is always given by the formula

\[\phi b = nABcos \theta \]

where theta is angle between the normal to a coil of n turns and A cross section area and the applied field
so you can induce the emf by a) changing area (sliding a coil into and out of the field) this is called as motional emf

b) changing b itself ( sliding in and out a magnet into the coil if you may)
c) by using an AC current
d) by rotating the coil (OUR ENTIRE FREAKEN TECHNOLOGY RUNS ON ELECTRICITY WHICH IS ACTUALLY PRODUCED BY THIS METHOD.. we don't have ANY OTHER METHOD of generating electricity :O ).. ofcourse other alternatives are only taking baby steps like solar cells.. !!


so any coil can generate a counter emf

Answer 2

Counter emfs occur when the magnetic flux generated by a current through a coil is changed rapidly as when the current flow is interrupted say by a switch. The emf generated depending on the inductance and the time interval of the interruption can be great enough to cause arc overs at the switch or arching through the insulation of the wire in the coil.

Answer 3

The loudspeaker is another example.

Answer 4

In this case, where a movable magnet is getting attracted to the fixed electromagnet, will C-EMF be generated? And since it not going "into" the coil will it be a huge amount? I doubt it would... What do you think?

@Mashy @Gleem @Vincent-Lyon.Fr

Ow thanks for your replies really interesting and helpful points!