Question Commonmode and differentialmode chokes are commonly

Solution

Differential current mode: this current is the one that flows out from a certain part of the circuit, reaches another circuit, and returns to the origin via a different route on the circuit board. These currents are the ones that carry data or some signal of interest.

Common mode current: This currents are the consecuence of another conduction route that exists in the circuit, though not as a clear-cut wire. A tiny amount of stray capacitance is generated between the wires on the between the wires on the circuit borad and the reference ground surface, creating a conduction where the capacitance flows commonly trough all wires on the circuit board and returns in the opposite direction along the reference ground surface. The currents that flows through this route are the common mode currents, these are high frecuency signals.

How does a differential-mode choke operate? The flux from differential currents cancels out in the choke, so that the choke does not act as an inductor.

How does a common-mode choke operate? Normally, common mode choke coils are designed so that the magnetic flux produced in the two coils by the differential mode current cancel each other out as much as possible. However, some common mode choke coils are designed so that not all of the magnetic flux cancels each other out, and some magnetic flux leaks.

I recommend you to do some research on these links, i did a homework about this topic and these links were very useful.

http://www.murata.com/en-us/products/emiconfun/emc/2011/10/28/en-20111028-p1

http://www.murata.com/products/emiconfun/emc/2014/07/24/en-20140724-p1

http://www.powerguru.org/basics-of-emc-and-emi/ (This one was written the author of several textbooks)