13 - Capacitor Voltage -Current Relationship

INTRO: Today we began dealing with capacitors, which we have previously covered in our Physics class. Although we did the basics of capacitors in circuits, we will go much more in depth with this circuit element in this class.

Pictured below is a capacitor. Capacitor are circuit elements that store energy/voltage in the Electric Field between two plates within itself. When charged, a capacitor can directly power a circuit for a short time since it has stored voltage. This is temporary though, since the voltage will eventually balance itself out. Capacitors are measured in capacitance (C), which is essentially how much energy a capacitor can hold.

 

LAB: CAPACITOR VOLTAGE - CURRENT RELATIONSHIP

In this lab we we see what relation exist between the voltage difference across a capacitor and the current passing through it. From what we know from capacitors, the higher the current should slowly decay while the potential stored inside the capacitor increases.

Here is a picture of our circuit diagram with a resistor in series with a capacitor. We will use several time-varying signals to power our circuit.

 

The time-varying signals we used our displayed below. We will use the common sine function, as well as the more uncommon triangle function.

 

Below is a picture of our diagram. We have the voltage going in and out, as well as the resistor in series with our capacitor.

 Below are the aforementioned time-varying signals that were applied as the voltage. The first two graphs show sine functions at 1 & 2 KHZ, as well as a triangular function of 400HZ.

 

Viewing the graph below you can see the relationship between the voltage  and current. They are out of phase by practically 90 degrees. This experiment backs up what we already know about capacitors, that the current drops to 0, when the voltage reaches its' max.