4/28/2014 RC-Circuit

RC-Circuit

Connecting Logger Pro withe the circuit which include power supply, capacitor, and resistor in series to measure the change of voltage over time across the capacitor(discharging).   

Connecting Logger Pro withe the circuit which include power supply, capacitor, and resistor in parallel to measure the change of voltage over time across the capacitor(charging).   

The graph of voltage vs time in the capacitor.  

The blue curve show the changes of voltage when the capacitor is charging.  

The red curve show the changes of voltage when the capacitor is discharging.
Base on the experiment data we can say the B value in the natural exponential equation should be fairly close to 0.  We also can say that the A value should be the original 4.5 Voltage which from the power supply.  Finally, the C value should relate to the capacitance and resistance.  

4/21/2014 Experiments: Capacitor in Series/Parallel & Capacitance vs Distance

Capacitor in Series/Parallel

 Using multimeter to measure the capacitance in series connection.  

 Using multimeter to measure the capacitance in parallel connection. 

Base on the experiment data to conjecture the relationship of capacitance in series and parallel connection.

Summary:

In this experiment we were given two capacitors. First measured the capacitance of each capacitor and record on the board.  We next set up the capacitors in series and in parallel as seen above.  After measuring the capacitance in both connections we can say that in parallel the capacitance of the two capacitors was simply the sum of their respective capacitance(Ctotal=C1+C2); in series capacitors add up inversely (1/Ctotal=1/C1+1/C2.)

Capacitance vs Distance

Using aluminum foil as the plates of capacitor to create a capacitor as show in picture.
Using multimeter to measure the capacitances in different distance between two plates.

Recorded experiment data that the capacitances in different distance.

 

Using the excel to make a distance of separation vs capacitance graph as show.  Base on the shape of the graph, the distance of separation and the capacitance have a inverse relationship.

Using the experiment data to calculate the kappa(dielectric constant).  The kappa value we calculated is 1.1 which is different to the real value 3.5 for papers.  The possible error is due to the pressure that we given on the book during the experiment.  

4/16/2014 Activities: DC-Circuits & Resistors

Activity 1: Series Circuits

Recorded data of measure the voltage across each light bulbs and current on each wire.  Base on the experiment data, the voltage of the battery is the sum of the voltage across the bulbs; the current is constant anywhere in the series circuits.  

Activity 2: Parallel Circuits

Recorded data of measure the voltage across each light bulbs and current on each wire.  Within the reasonable uncertainty of the meter, the voltage is constant in parallel circuits; the current is inverse proportional between junction and wires. 

Summary of activity 1 and 2

Summary of voltage/current in series/parallel circuits.

Activity 3: Decoding and Measuring Resistors    

Apparatus: 4 band code resistor and 5 band code resistor(blue).  

Determining the resistance by reading the color bands on the resistors.  

The table of resistors color coding.  

Follow the color code of resistors to calculate the resistance

Comparing the measured resistance and reading value.  There are 99% accurate in the 4 bands resistor and 97% accurate in the 5 bands resistor.   

Activity 4: The Equivalent Resistance for a Network

Example of simplifying the graph of circuit by combining the resistors. 

Calculated and measured value of total resistance in the network.

The combination of resistors represent as the network show in previous picture.  

 Using the multimeter to measure the resistance in the network.  

Summary:
Base on the result of our experiments of resistance, there is direct proportional relationship in series connection; inverse proportional relationship in parallel connection.   

4/14/2014 Estimate of the Potential from a Charged Ring & Experiment: Electric Potential Lab

Estimate of the Potential from a Charged Ring

Estimate the electric potential at point P due to the charged ring.  

Divide the ring into 20 elements of charge dq and calculate the total V at a distance of x = 20 cm from the center of the ring by using the excel spreadsheet.  

Calculating the total V at point P where x = 20 cm by the spreadsheet.  

Moves the point P to the position as show in picture, the distance between the point P and the ring is not constant.  

Calculating the total V at point P by using the spreadsheet.

Experiment: Electric Potential Lab

To determine the electric potential between two points due to a power supply (electric potential difference). We set the power supply to 15 V and using a power meter tested two points on the sheet. First we tested points on the two metallic paint marks and got a reading of 15.54 V. When we measured the potential difference between two points on the lower and higher potential conductor we got a value of 0.

Next we clipped one end of the power meter to the painted metallic circle and took measurements of electric potential X cm away, in increments of 1 cm. We also calculated the ratio between each pair of points. Our results are listed above.

Based on our data the direction of the electric field is in the -x direction. As the distance between the points continues down the +x direction the electric potential increases. This means it must be moving against the electric field which would thus have to pint in the -x direction.

4/9/2014 Quiz & Electric Potential

Quiz

In this quiz, we got assign to do the most brightest lighting system.  We put batteries in series and light  bulb.  

Redraw the diagram by using specific symbols.   

Electric Potential 

The experiment that set-up in which 200 grams of water was placed in a cup along with a coiled wired heater. The length of coiled wire in the heater was 42 cm. It was attached to a 4.5 V battery and placed in the cup of water for a total of 10 mins. A temperature probe placed inside of the cup recorded the temperature as it changed in logger pro. During the 10 mins the "heater" was submerged in water we calculated what the temperature change of the water should be given the length of the wire, voltage of battery, mass of water, and any necessary constants.

Calculating the uncertainty

the temperature change results from logger pro for each experiment. The blue data set was the 9.0 V experiment and the red data set was the initial 4.5 V experiment.

4/7/2014 Resistance & Resistivity

Resistance

Measuring the current go through the resistor at different applied voltage.

Recorded experiment data(I1) and compering to other group's data(V2 & I2).  In the voltage vs current graph, series 2 has greater resistor then series 1.  Series 2 has less amount of current go through when there is same voltage applied.  

Relationship between voltage and current and deriving the unit of resistance.  

Resistivity

Measuring the resistance in different materials such as copper and nickel silver(different length) to see the relationship between length of wire and resistance. 

Recorded experiment data from measured resistance in different material/length.  The resistance vs length graph showed that copper has less resistance than silver even the copper soil has tan times of length than nickel silver.  There is linear relationship between resistance and length.  

The relationship between resistance and length/cross section area/resistivity of material.