2N4401 is a NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pin. 2N4401has a gain value hfe of 500; this value determines the amplification capacity of the transistor. An introduction to the 2n4401 is available at: https://www.theengineeringprojects.com/2018/02/introduction-to-2n4401.html
