How a transistor works in switch …

 <a href="https://www.elprocus.com/transistors-basics-types-baising-modes/">A transistor is a three-terminal semiconductor device</a> which can be used for switching applications, amplification of weak signals and in quantities of thousands and millions of transistors are interconnected and embedded into a tiny integrated circuit/chip, which makes computer memories. A Transistor switch, which is used for opening or closing of a circuit, that means the transistor is commonly used as a switch in the electronic devices only for the low voltage applications because of its low power consumption.Transistor work as a switch when it is in cutoff and saturation regions. In this article, we will discuss how to use a transistor as a switch

Transistor As A Switch

If the circuit uses the BJT transistor as a switch, then the biasing of the transistor, either NPN or PNP is arranged to operate the transistor at the both sides of the I-V characteristics curves shown below. A transistor can be operated in three modes, active region, saturation region and cut-off region. In the active region, transistor works as an amplifier. The two operating regions of transistor Saturation Region (fully-ON) and the Cut-off Region (fully-OFF) were used to operate a transistor switch.