28April2014

Capacitors: Discharging and Charging Properties 

The set up is used to measure the Voltage produced when the Capacitor is charged and discharged. We used LoggerPro to measure the Potential (V) verses the time to charge and discharge. This helped us fins a relation between the potential voltage and time in charging and discharging. 

Here is a diagram for the layout. To charge it we needed to set it up in series and discharge we ran the set up in parallel. We used a 3.6kOhm resistor and P=4.5V. We will used this to also determine the value of tor =Resistance *Capacitance.

This is the actual set up of the resistor in parallel with the resistor.  

While it was discharging we expected a non-linear relationship and doing come algebra we determined the unit value of tor= RC is measured in seconds.  

These graphs show the relationship of the potential verses the time and we see the discharging of the capacitor in red and charging of capacitor in blue. Here we can see the value of C for the more accurate charging fit to be 0.002276 which is a representation of C=1/tor=1/RC in the equation V=Voe^(-t/RC)

To verify the value of C we took the labeled value resistance and capacitance used in the experiment and determined the theoretical value of tor to be 0.002273. This with the experimental value in our charging circuit to be 0.13% which is a very percent error. We experienced some error when finding the value of C for the discharging unit we did it three different time and saw no change in the result. One reason that this error occurred be the result of the machine measuring the initial voltage to be 4.88V based on the value of A in the graph. But there was no visual reason for this error but if allowed more time we would of tried new instruments and compared which instrument was creating the error by process of elimination. 

21April2014

Capacitors in Series and Parallel 

The capacitors were placed in series and in parallel and the voltage was measured in order to determine a relationship between the configuration and voltage produced. 

We observed that the when the capacitors were placed in series they produced a voltage 0.618V given that the value for c1=1.03V and c2= 1.45V we found the relationship to be the product of the voltage over the sum of the voltage. 

But in parallel we found the total voltage to be 2.50V given the measured value of c1 and c2 we found when resistors are placed in parallel the relationship is the sum of the voltages. 

Homemade Capacitor 

In this experiment we used foil paper of a known area and sheets of paper in sets of 12 pages of a known thickness to create a capacitor in order to determine the relationship of the capacitor with the area of the conducting foil and the distance between them. We  can also determine the relative permittivity of the dielectric material with this relationship. 

The voltmeter was used in order to calculate the capacitance for a larger and smaller area of foil. 

For the larger area the capacitance was graphed verses the distance created with the paper. Considering that the area remained constant this graph indicated that the distance is inversely proportional to the capacitance. As the capacitance decreases the distance increases.

From our data set we can determine k which is the relative permittivity of the dielectric material between foil plates. From our first data point we determined k to be 3.49 for paper. Compared to the actual value of k for paper of 3.5 we found percent discrepancy to be 0.28%. This percent error indicated that our method of creating a capacitor was very effective. Thus our k value was very close to the actual value of k. 

16April2014

Testing the Loop Rule with Real Circuits

The circuit board was set up to determine the different currents in circuit. Our group choose not to use the potentiometer in our circuit board because of the large source of error it created, instead to be more efficient we choose to use 2 1kOhm resistors to gather our data. We will find the percent discrepancy using the loop rule to determine the theoretical calculation of the different currents and compare it with the actual value found in the circuit board above.  

 The current that is found running across the 3.6k Ohm resistor was found to be 0.148 A.

The current that is found running across the 2k Ohm resistor was found to be 1.005 A. 

The current that is found running across the 2.2k Ohm resistor was found to be 1.151 A.

In this picture you can see the schematic for the circuit we set up. In class we used the loop rule to find three equation with three unknowns. We used a calculator to determine the different currents that run across each resistor which gave us our theoretical current values at each resistor. We found a percent discrepancy for the current over the 2.2kOhm resistor to be 0.96%, 2kOhm resistor to be 0.60%, and 3.6kOhms resistor to the  5.7%. The precent discrepancy tell us that loop rule is a effective method of determine the current that runs across the resistor. 

Resistors in Series and in Parallel 

The resistance on the resistors was determined in two different configurations series and parallel with the volt meter in order to determine a relationship with the different configurations. 

We found that when the resistors are in series they are additive. We observed when the resistors are in parallel they are additive: 1/(Rtotal)=1/R1+1/R2+...1/Rn where n is the number of resistors in parallel. 

In this picture we used the relationship of the configuration of the resistors to determine the total resistance of the circuit when these configuration are combined above. The theoretical resistance was determined to be 52.5ohms

Here we can see the configuration of the resistors like the diagram above and the expected resistance measured with the voltmeter was determined to be 50.0 ohms. 

The percent discrepancy was determined to be 4.76% which is within the 5% error expected of the ceramic resistor as seen in the picture above. 

14April2014

Electrical Potential Lab/Activity

The electrical potential was analyzed in this experiment in order to gain a understanding of the electrical potential difference and the effects of the electrical field as the distance increases from the power supply. The Potential difference between the two metallic paint marks was determined to be 15V. 

The Potential difference between the lower and higher potential conductor was determined to be zero for both. This tells us that no work was done because W=deltaV*D, deltaV=0 in both cases therefore no was done in the case of the lower potential conductor and higher potential conductor. 

The graph represents the the potential change of the increasing distance from the power supply. Looking at the data the positive charge goes from higher to lower potential in the negative x direction, which can be seen in the graph above as the distance increases so does the electrical potential . 

Here are the questions that address what it takes to the move the charge or change the potential energy. 

Here we can see the that volt meters are equivalent to newton coulombs.

Question1 deals with a situation when Point A and B are in a area of no electric field.

Question 2 deals with a situation where A and B are in a strong electric field.  

9April2014

In Class Quiz

This is the diagram for our attempt to create a very dim light.

Here is a more efficient method for creating a very dim light was setting the bulbs in series with the batteries in parallel. 

This is the circuit diagram for the configuration of a dim light set up. YAY!!

4.5 V verses 9 V

 This is the graph for the set up of water being powered with two different voltages in order to find a temperature difference and compare the results.

Using 4.5 V we were able to heat the water and determine the power, heat, and temperature difference. From these calculation we found the uncertainty in order to compare the percent uncertainty.

Using 9 V we were able to heat the water and determine the power, heat, and temperature difference. From these calculation we found the uncertainty in order to compare the percent uncertainty. 

Two different values of resistance were used in the experiment due to the variation in resistivity data. therefore four different percent uncertainties were calculated and we found they all ended up being the same. Basically doubling the power did not affect the uncertainty because the uncertainty is related to the system. 

The correct value for the resistively was 5.96 ohms base on our calculations ant the temperature difference from the graph. 

7April2014

Volts verses Current

Collecting data from a wire wrapped arounds a wood cylinder  in order to interpret the relation hip between amps and current in a closed circuit.

The top coil is form the lab table across from us and the coil on the bottom is from out lab table. We wanted to compare the results of both groups to see if there are in relationship in the current change. They are about the same coils wrapped around but our groups coils are spread out over the wood cylinder compared to theres which are packed to the right side of the cylinder as seen above.  

Comparing coil with Lab table next to us.

The graph represents the volts verses the current for both lab groups. Our data is in blue and their data is in red and the data and it is apparent that both groups produced a graph that shows the resistance as linear relationship between the current and the voltage. There resistance was higher at 23.319 ohm and our was lower at 16.14 ohms. This can be attributed to the material the wires are made or the number of coils given that they had as it appears in the picture above one extra loop. In addition the amp-meter used to measure this data may have a affect on the results also. But the main idea is that there is a linear relationship. 

Creating a Light with a Battery,Wire, and Bulb.

This picture shows the light created when a wire is used to close a circuit between the battery and light bulb to carry a current and create light.

Here we can see the battery gives the energy to the bulb and the bulb then uses the energy to create light. How cool is this? Super cool!! I will remember this at graduation! 

The wire helps to circulate the energy from battery or basically give a path for the electrons to  move.  

Resistance as a Function of Length

In this experiment we compared several different coils of varying diameters, resistance, and wire length. One was copper and rest were made of nickel silver we measured the resistance in all the coils and compared them by graphing the resistance as a function of length in order to determine a relationship between the diameter, resistance, and length. 

This graph shows the relationship of the data collected we have the corrected resistance of the y-axis and the increasing length of the wire on the x-axis. 

From the graph we can determine that the resistance is linearly proportional to the length of the wire. If we look at the last two points in the graph we can see the length is constant but the resistance is greater when the diameter is smaller therefor the resistance is inversely proportional to the diameter or the area of the wire. We determined the constant of proportionality to be the resistivity measured in (Ohm*meter). 

26March2014

Gauss Law Active Physics

This lab was done to develop a understanding about the way the electric field is affected by distance from a charged sphere and shell.