146c5814_What_is_an_Ideal_Op_Amp___Ideal_Op_Amp
[Characteristics] Zero Output Impedance [Real Op Amp] A real op amp will always have some output impedance, though it is low. A typical value can be 75â„¦. [Ideal Op Amp] 
An ideal op amp will have zero output impedance. When an op amp produces its output signal, we want the op amp to have zero voltage so that the maximum voltage will be transferred to the output load. Voltage is divided in a circuit according to the amount of impedance present in a circuit. Voltage drops across a component of higher impedance. In order for the voltage to drop across the output load, that load must be of greater impedance than the output of the op amp. This is why, ideally, we want the output impedance of the op amp to be zero
What is an Ideal Op Amp?
Ideal Op Amp