What type is this Op amp? What is formula for calculating Vo.
When dealing with operational amplifiers you have to consider two things : First there is no current coming in or out of op amp (not true in real life applications). Second , voltages at the positive and negative inputs of the opamp is always equal. When we look at the positive input rail, you can see that output voltage and the ground form a voltage divider circuit. if we call the voltage at the input, Vin. Vin = (Vo x 200000)/ 300000, Vin = 2Vo/3 . Remember what i said before voltages at the positive and negative inputs of the opamp is always equal.That means voltage of the inverting input rail is also 2Vo/3.Now remember rule number one : there is zero current in the input rail , which means current coming from the 400mV source is going straight to output without visiting the input.İf we calculate the equation for that : (400-2Vo/3) /5000 = (2Vo/3-Vo)/50000 . If you solve the equation, you can see that Vo equals to 631.57 mV.