04-12-2016

04/12/2016

Review of Capacitor and Inductor Lab

I. Introduction:

Today we spent most of our time reviewing all the knowledge we had learned in 4B class,specifically the capacitors and inductors, their relationships with currents, resistors, and voltage.

Professor Mason introduced us to rage bridge, which was the complex combination of capacitors. Due to the fact that the bridge had a large spark because the mechanical engineer designed the bridge, not an electrical engineer.

 2. Design of capacitor:

Here is our simple design of capacitor. We believed that we could design a variable capacitor by pumping in and out the dielectric oil; however, the downs side is that the dielectric oil would be dried out eventually

We knew that I=cdV/dt. P=VI=Cvdv/dt. We then take the integral with respect to t to find the total energy

Given the current graph with respect to time of a capacitor. We had to plot a graph of voltage with respect to time. Our approach was to use the formula I=c*dV/dt. therefore, V=Ict

Given the circuit with a capacitor on the top. Our goal is to find the current of i2. Since we already knew the current in the loop 1, we used mesh analysis to find the current in loop 2, therefore, we could find the voltage across resistor R2

We were given some more sinusoidal graph of voltage and triangular wave of voltage. Our goal is to find the graphs of current over time, using the fact that I=cdV/dt. We could find the corresponding graph of current over time

 II. Lab: Capacitor and Voltage in the circuit
1. Introduction:
 Our goal is to find out the relationship between the capacitor and the current pass through that capacitor over time. Using the two graphs we had derived previously for the prelab, we expected our experimental labs should look the same

The blue graph measures the voltage across the capacitor. The orange graph measures the voltage across the resistor, notice that the orange graph is a sin function, whereas the blue graph is a cos function, which indicates the voltage across the resistor has a phase shift of pi/2 

Here is the same setup but we used the 2kHz for the frequency, these are the graphs of voltage and current across the capacitor

Here is the picture of capacitor voltage waveform. We input 100Hz triangular voltage here

Here is our simple setup for the lab

Our data for the lab, we checked with the other group to make sure our data is correct. Notice that for part A and part B, the voltage across C1 is closely followed by the voltage across C2

 III. Capacitor explosion:
Professor Mason demonstrated a capacitor explosion, what he did basically applying  a large voltage a capacitor, a capacitor would be exploded

what was left after the explosion

Here is a picture of the polar capacitor.

 IV. Equivalent capacitor:
Here is a rule of thumb: equivalent capacitor is the opposite of equivalent resistor, which means that we have to add when they are in parallel and inverse when they are in series

Given a simple of capacitor, we had to find the  equivalent capacitor, which in this case we approached right to left.

Here is a short summary of all the formulas we should know

 V. Summary:
For today lab, we spent most of our time reviewed all the knowledge we had learned in 4B class. We did derive some equation using derivative and integral to get  the current and voltage across the capacitor. For the lab part, we applied different voltage sources to observe the change in current using the built in scope of the analog discovery