impedance

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Impedance is the complex-valued generalization of resistance. It may refer to:

• Acoustic impedance, a constant related to the propagation of sound waves in an acoustic medium
• Electrical impedance, the ratio of the voltage phasor to the electric current phasor, a measure of the opposition to time-varying electric current in an electric circuit
• High impedance, when only a small amount of current is allowed through
• Characteristic impedance of a transmission line
• Impedance (accelerator physics), a characterization of the self interaction of a charged particle beam
• Nominal impedance, approximate designed impedance
• Impedance matching, the adjustment of input impedance and output impedance
• Mechanical impedance, a measure of opposition to motion of a structure subjected to a force
• Wave impedance, a constant related to electromagnetic wave propagation in a medium
• Impedance of free space, a universal constant and the simplest case of a wave impedance