A connection is commonly said to be bridged if the load impedance is at least ten times the source impedance.
Demodulation yields a low-noise audio frequency signal with a very low source impedance.
The source impedance (that seen by the loudspeaker) includes the connecting cable impedance.
In the case of the L-pad, the right figure will be used if the load impedance is greater than the source impedance.
Z is a function of the source impedance.
Such a configuration serves to either prevent reflections when transmission lines are involved, or to maximize power delivered to the load given an unchangeable source impedance.
Adjusting the source impedance or the load impedance, in general, is called "impedance matching".
Consider a real source impedance of and real load impedance of .
If a reactance is in parallel with the source impedance, the combined impedance can be written as:
If the source impedance matches the line, reflections from the load end will be absorbed at the source end.