Current Into Op-Amp Circuit
The circuit above contains an ideal operational amplifier (op-amp). At a particular instant, source voltage , and capacitor voltages and .
In this instant, what is the source current ?
Note: The op-amp has an external power supply, which is not shown
The answer is 2.333.
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1 solution
In a feedback loop the ideal op-amp maintains zero potential difference between its input terminals. Since the + terminal is at v C 1 = 1 V , and the output is connected to the - terminal, the output voltage is also 1V. To that value we add v C 2 = 2 V and we get 3V, the potential at the point when the two resistors and the C 2 capacitor join each other. The voltage drop on the 3 Ω resistor is 10V-3V=7V and the current is 2.33A.