The inverting amplifier connects the input voltage through a resistor to the inverting terminal, grounds the non-inverting terminal, and has a feedback resistor between the inverting and output terminals. By applying KCL and assuming the operational amplifier to be ideal, the expression for gain is determined. Inverting amplifiers reverse the input signal's polarity while amplifying it, making them useful for noise cancellation. The microphone selects the input noise signal and inverts the signal in the cancellation circuit to eliminate the noise. Inverting op amps has applications in audio processing for signal amplification, conversion, and filtering. Non-inverting amplifiers have the input voltage applied directly to the non-inverting terminal, a resistor between the ground and the inverting terminal, and a resistor for negative feedback. Applying KCL at the inverting terminal and substituting the voltage values provides an expression for voltage gain. If the feedback resistor is short-circuited or if the input resistor is open-circuited, the gain becomes unity, creating a voltage follower. They convert high-impedance inputs to low-impedance outputs, enabling efficient signal transfer to low-impedance loads.