Experiment 1 : Transistor tester

How the circuit works :

The LED needs about 1.8 V to light up.

A transistor is a device that can act as a switch or as an amplifier, depending of the circuit design.
The transistor is used here as a current amplifier. 
By touching A & B, a small body current will be amplified and will slightly close the C & E gate, so the LED will get the needed Voltage.

A small voltage applied to the Base, will be greatly amplified and the path between Collector and Emitter will conduct electricity.

The body resistance is so great ( around 2 Meg Ohms ), so we need a dark area to see the LED illuminate. Our body resistance conducts electricity, needed to turn the transistor on.

This is a great transistor tester to test the amplification factor.
Later on, we will calculate the transistor voltages.