The P-N junction diode is appeared in the year 1950. It is the most essential and the basic building block of the electronic device. The PN junction diode is a two terminal device, which is formed when one side of the PN junction diode is made with p-type and doped with the N-type material. The VI characteristics of PN junction diode in forward bias are non linear, that is, not a straight line. This nonlinear characteristic illustrates that during the operation of the N junction, the resistance is not constant. The slope of the PN junction diode in forward bias shows the resistance is very low. When forward bias is applied to the diode then it causes a low impedance path and permits to conduct a large amount of current which is known as infinite current. This current starts to flow above the knee point with a small amount of external potential. PN Junction Diode VI Characteristics in Forward Bias PN Junction Diode VI Characteristics in Forward Bias The potential difference across the PN junction is maintained constant by the depletion layer action. The max amount of current to be conducted is kept incomplete by the load resistor, because when the PN junction diode conducts more current than the normal specifications of the diode, the extra current results in the heat dissipation and also leads to serve damage to the device. ... https://www.youtube.com/watch?v=aITOgwa31Xg

A multimeter or a multitester, also known as a VOM (volt-ohm-milliammeter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter can measure voltage, current, and resistance ... https://www.youtube.com/watch?v=urfwpS3IgzE