Definition of Input impedance
In electrical engineering, the input impedance of an electrical network is the measure of the opposition to current (impedance), both static (resistance) and dynamic (reactance), into a load network or circuit that is external to the electrical source network. The input admittance (the reciprocal of impedance) is a measure of the load network's propensity to draw current. The source network is the portion of the network that transmits power, and the load network is the portion of the network that consumes power.
For an electrical property measurement instrument like an oscilloscope, the instrument is a load circuit to an electrical circuit (source circuit) to be measured, so the input impedance is the impedance of the instrument seen by the circuit to be measured.
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Questions people ask
Real questions from the Stack Exchange community – follow a link to read the discussion.
- Is there any standard for the input impedance of an audio amplifier · Electronics SE
- matching input and output impedance in an audio circuit · Electronics SE
- understanding input impedance theory · Electronics SE
- how to increase input impedance via bootstraping? · Electronics SE
- 555 Input Impedance · Electronics SE
- Do audio impedance mismatches cause reflection (ie, 8-Ohm output to 20kOhm input) ? Does it matter? · Electronics SE
Frequently asked questions
What is Input impedance?
In electrical engineering, the input impedance of an electrical network is the measure of the opposition to current (impedance), both static (resistance) and dynamic (reactance), into a load network or circuit that is external to the electrical source network.
Sources & credits
- Wikipedia: Input impedance – CC BY-SA 4.0
- Image by Cjp24 – CC BY-SA 4.0