Also we can take the knowledge we know of the diodes to analyse the internal diodes of the transistor.Įmitter-Base terminal: There is a diode in between the emitter-base terminals so those two terminals should function as a normal diode and conduct in only one direction.Ĭollector-Base terminal: There is a diode similar to the collector-base terminals. Identification of the transistor can be done using the resistance of the diodes present inherently inside the NPN transistor. The section other than emitter which collects the charges is called the collector. The base-collector junction is reverse biased which provides a high resistance in the collector circuit. The base-emitter junction is forward biased which allows a low resistance for the emitter circuit. The middle section of the transistor, which forms the two PN-junctions between emitter and collector, is called the base. To supply a large number of charge carriers, the emitter is always in forward biased when compared to the base. One section which supplies charge carriers is called the emitter. It forms the two aforementioned PN-junctions between the emitter and collector. With one side emitter and another is collector while the base lies in between. Like a PNP transistor, this NPN transistor is also a current controlled device.Ī transistor has three sections of doped semiconductors. In short, the NPN transistor conducts when the collector terminal is at a higher potential than both the base and the emitter. The voltage between the baes and emitter terminals is called V BE, and is more positive at the base than the emitter because for NPN transistor, base terminals should be higher in potential than the emitter.Īlso, there is representation of the voltage between the collector and emitter, it is denoted by V CE, and this voltage is positive with respect to emitter. The schematic diagram of a NPN transistor is shown in the above figure. it converts and transfers the internal resistance from low resistance of emitter – base to the high resistance of collector – base circuit. The name transistor is derived from the “ Transfer of Resistance” i.e.