Functionality of the transistor can be checked by assembling the connection diagrams. The circuitry includes a NPN transistor. (If the LED lights up in the case of any direction switching of the power supply source with any two terminals of the transistor, it means it is broken down.)

Implements required for the experiment

– NPN transistor
– 10 kΩ variable resistance to protect the LED and the transistor
– 4.5 V power supply source
– Wires