Operational Amplifier: Non-Inverting Op-Amp and Op-Amp as Buffer (Op-Amp as Voltage Follower)

In this video, the non-inverting op-amp configuration and how to use Op-Amp as a buffer or as a voltage follower (Unity Gain Amplifier) has been discussed.
In this video, the input impedance of both inverting and non-inverting opamp configuration has also been derived.
And inverting and non-inverting op-amp configurations are compared with respect to input impedance.

Non-inverting Op-Amp:
In non-inverting Op-Amp configuration, the input is applied at the non-inverting terminal of the op-amp and feedback is applied from the output the inverting end of the op-amp.
In this configuration, the input and output voltages are in phase with each other.
The input impedance of this configuration is ideally infinite and practically it is very high.

Op-Amp as a buffer (Op-Amp as Voltage follower):
Op-Amp can be used as a buffer in the non-inverting configuration. In this configuration, output voltage follows the input voltage. Or in another way, the gain of the Op-amp is one (Unity). That's why it is also known as unity gain amplifier.
The input impedance of this configuration is very high and that is why it can be used to isolate the different circuit stages.

The timestamps for the different topics in the video is given below:

0:52 Non-Inverting O-Amp Configuration
1:51 Derivation of Closed Loop Voltage gain for Non-Inverting Op-Amp Configuration
5:00 Advantage of Non-Inverting Op-Amp configuration over Inverting Op-Amp configuration
6:09 Input Impedance of Inverting Op-Amp
7:25  Input Impedance of Non-Inverting Op-Amp
9:28 Op-Amp as Buffer (or Op-Amp as Voltage Follower)