Capacitors are components that stores and releases energy, which is useful for smoothing out the voltage within a circuit. Capacitors are measured in Farads, however they are mostly used from pico Farads (pF) to micro Farads (µF). They come in different varieties like the electrolytic capacitors, or ceramic capacitors. The electrolytic capacitors contain a polarity, which means that they have an anode and a cathode, while the ceramic capacitors does not have a polarity.
Figure 1: Capacitors and their symbol
How do they work?
When the circuit is powered on, the Capacitors stores up energy from the power source, in which the energy is also sent over to other components as well. However when the circuit is disconnected from the power source, the circuit is still powered on due to the energy from the Capacitor. The Capacitor releases the remaining energy until no energy is left to power on the circuit. This creates a "smoothing" or "fading" effect to the circuit as the voltage gradually decreases when the Capacitor is fully charged up and the circuit is disconnected from the main power source. The graph below shows how Capacitors behave
Figure 2: How Capacitors behave
Testing
The video below shows how the circuit is behaving. The voltage supply is set at 5 Volts. As I disconnect the circuit, the LED would fade, which decreases the voltage of the Capacitor as shown in the multimeter. When I reconnect the circuit to the power supply, the voltage of the Capacitor reaches up to 5 Volts again.
