The input voltage of an non-inverting op-amp is inputted at the non-inverting terminal of the opamp. The purpose of a noninverting opamp is to amplify a signal. The amount of amplification/gain can be determined by the following equation:
If the input voltage is 5 V, Rf is 10kΩ and R1 is 10kΩ, then the opamp will have a gain of 2. This means that a 10 V single will be outputted from the amplifier.