Transistor Switching

In this first picture, we can see that the LED has a power source to that barely allows the LED to light. Much like a probe, large black wire with no connectivity will either send ground or power to the transistor which will either brighten the LED or turn it off.


Here, you can see that the large black wire is connected to the positive terminal of the board. As a result, the LED light up much brighter than it originally was. This helps to indicate that the transistor used was a PNP transistor.

And finally, once the same black wire was connected to ground, there was not complete circuity and the LED did not turn on at all.

While using the NPN transistor, the LED was not lit because of the button, which regulated the power signals to transit over to the transistor. Since there is no power to begin with, a ground signal could not be completed to light the LED.



However, once the button was pressed, the ground signal completed the circuit which allwed the LED to light up.