This causes an increase in the voltage at the junction of the LDR and the 100k resistor, triggering the 555 timer IC. The 555 timer IC turns pin 3 (output pin) low, which is connected to the cathode ...

In the picture we see the material and the method of joining it. A diode has its two parts, the anode and the cathode. The anode is the positive part and we connect the resistor to it. The resistor is ...