capacitors

Today we started class with learning about capacitors. capacitor consists of two conducting plates separated by an insulator or dielectric.
Capacitors stores energy. They act completely opposite of resisters.
C= q/v (capacitor is measure of how much charge per volt stored on a plate

We did following RC circuit to obtain E stored in Capacitors by using source transformation and open circuiting capacitors.

LAB: Capacitor voltage current relations

In this lab we measured the relationship between the voltage difference across a capacitor and the current passing through it and we compared it through graphs displayed below. 

Procedure: we applied several types of time varying signals to a series combination of a resistor and a capacitor. The voltage difference across the resistor in conjuction with ohm's law provided an estimate of the current through the capacitor .

Below was set up of our RC circuit in series so that the current through the capacitor was the same as the current through the resistor. 

Pre LAB:  we sketched capacior voltage and capacitor current sinusoidal wave and triangular wave  using the capacitor voltage current relations. 

As you can see in both sketch that pink color is current and black is voltage.  In both graph when current is positive , voltage is negative and vise versa. 

Triangular input: As you can see in below sketch that red line which indicates the current is almos in square shape. 

This graph shows that when the voltage doesn’t change across the capacitor, current doesn’t flow; to have current flow, the voltage must change.

Graph of voltage is sine graph and current is cosine grpah which shows that they are 90 degree out of phase.

the current going through a capacitor and the voltage across the capacitor are 90 degrees out of phase
The current leads the voltage by 90 degree

capacitors in parallel combine in the same manner as resistors in series and in series capacitors combine in the same manner as resistors in parallel.

Below is an example we did in class to get Ceq.

Inductors:  consists of a coil of wire. inductor exhibits opposition to the change of current flowing through it. Its units are henrys (H)

It acts like a short circuit to DC.

Below is the comparison of capacitors and inductors which shows that capacitors are completely opposite of inductors.

LAB : Inductor Voltage current relations . This lab was demonstrated by Mr. Mason. 

Below is the graph of Inductor voltage current. The current going through an inductor and the voltage across the inductor are 90 degrees out of phase. Here the voltage leads the current by 90 degrees