# What is the input impedance of an op amp?

According to all the books, some of them said, op amps are supposed to have zero output impedance, or very low. That means the output voltage won't change, just in case the output current changes. Some older op amps had an output impedance of 600 Ω or 50 Ω.
A.

### What is the input impedance?

The input impedance of an electrical network is the measure of the opposition to current flow (impedance), both static (resistance) and dynamic (reactance), into the load network being that is external to the electrical source.
• #### What is low output impedance?

A high impedance means that the circuit draws or provides little power on the signal. A low impedance means that the circuit draws or provides more power on the signal. Say the circuit under question (circuit B) is interfaced to circuit A on the input side and circuit C on the output side.
• #### What is the early effect?

The Early effect, named after its discoverer James M. Early, is the variation in the effective width of the base in a bipolar junction transistor (BJT) due to a variation in the applied base-to-collector voltage.
• #### What is impedance on headphones?

Most headphones with low impedance (less than 25 ohms, approximately) require little power to deliver high audio levels. For example, low impedance headphones will work well with equipment with weak amplification like portable music players, phones, and other portable devices.
B.

### What is the use of high input impedance?

The answer is the high input impedance is good for the amplifier circuit to have a good amplification of the input signal other wise we get low voltage in, so low amplification. To get all the voltage from a source to a target without loss.
• #### What is the input impedance of a multimeter?

Impedance basics. Most digital multimeters sold today for testing industrial, electrical, and electronic systems have high impedance input circuits greater than 1 megohm. In simple terms this means that when the DMM is placed across a circuit for a measurement, it will have little impact on circuit performance.
• #### What is the best impedance for headphones?

Headphones with higher impedance (25 ohms and over, approximately) demand more power to deliver high audio levels. As a result, they are protected from damage caused by overloading. They can also be used with a wider range of audio equipment. DJ headphones generally range from 25 to 70 ohms.
• #### What do you mean by impedance matching?

In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load.
C.

### What is a high impedance input?

In electronics, high impedance means that a point in a circuit (a node) allows a relatively small amount of current through, per unit of applied voltage at that point. High impedance inputs are preferred on measuring instruments such as voltmeters or oscilloscopes.
• #### What are low impedance injectors?

High-impedance injectors, also called saturated fuel injectors, are sent a 1–1-1/2-amp current signal to open, and that current stays on until the injector closes. Low-impedance injectors, also called peak-and-hold injectors, are sent a more powerful electrical signal, usually around 5–6 amps, to open.
• #### What is the advantage of having high input impedance?

The answer is the high input impedance is good for the amplifier circuit to have a good amplification of the input signal other wise we get low voltage in, so low amplification.
• #### What is low output impedance?

A high impedance means that the circuit draws or provides little power on the signal. A low impedance means that the circuit draws or provides more power on the signal. Say the circuit under question (circuit B) is interfaced to circuit A on the input side and circuit C on the output side.

Updated: 11th October 2018