I light up the LED...

Diode is a special device that having many functions.
It act as a valve that only allow 1 flow of current, as a bulb give out the light, as a filter in circuit also.
Diode consumed power and causing the voltage drop.

See how I measured the LED ( light emitting diode ) by using multimeter, as the voltage flow through the LED, it light up. It proven that I connected it with the correct way because diode is polarity.
Upon the diode has polarity, it is necessary that we defined the anode and cathode of diode.
Otherwise the device will burn out.

This week we also learn the transistor device.
When lecturer asking what is the function of transistor, no one of us can answer the question.
Actually transistor uses for control voltage, as a switch and amplifier. Transistor divides to NPN and PNP type. The lecturer explained about the usage and the method of analysing the transistor of circuit.
By using multimeter, we can easily detect the type of transistor and the pin of transistor.
As we find out the the base pin, we can easily find out the collector and emittor.
Another method is by using component analyser, this is the faster and easier method to analysed pin and voltage of transistor.