For the attached circuit, find the open circuit voltage (Voc) if the op amp is ideal. 0.25V -5V 5V -6V 15V 0V

## Answer

In the given circuit, we need to calculate the open circuit voltage V_OC. The given op-amp is ideal. To find the V_OC, we use 2 golden rules of op-amp. They are (1) The voltage at op-amp terminals is source. V_+ = V_- (2) op-amp draws no current. To find the output voltage V_O, we use superposition theorem. We first make inverting terminal voltage zero and then calculate output voltage V_o. similarly for non-inverting terminal voltage. At last, we add the both values of V_o. rn (1) non-inverting terminal input voltage is zero. 15 – V_-/5 = V_- – V_o/15 15/5 = -V_o/15 – V_o = 45 V_o = -45 volts (2) inverting terminal input voltage is zero. By voltage division rule V_+ = 15 times 12/6 + 12 = 15 times 12/18 = 15 times 2/3 = 10 volts. rn now, we apply KCL at ‘-‘ terminal. Here V_+ =