Impedance matching is setting the input impedance (load) equal to the fixed output impedance (source) to which it is connected, in order to maximize the power transfer.
Matching is obtained when...
An impedance matching device is used to test the resistance, inductive reactant and capacitive reactant in a circuit. If one component did not match the impedance of the conductor, some of the...
For instance:
A microphone rated at 150 ohms to 300 ohms is considered low impedance.
About 600 to 2 000 ohms is medium impedance,
and 10 000 ohms or more is high impedance.