Day18

Oscilloscope and Mystery Box:

In this class time, AC/DC and other components of the oscilloscope were studied, and more and more familiar of  the oscilloscope is learned for future labs. All observations are made on the whiteboard photos below.

Mystery box:

After knowing the property of AC and DC and other components of the oscilloscope, we are going to measure a mystery box. This is how a mystery box looks like.

 Using the oscilloscope, we can find the frequency, time and voltage. 
                                   The value makes sense.  

Day17

Capacitors in Series and Parallel

1. A Capacitance Puzzle:
Predict: When the Capacitor connected in parallel. The capacitance equals to the sum of the each capacitance.
Experiment set up:

2. Quantitative measurements on an RC system.

Predict: When the battery is removed or turn off from the circuit, the voltage across the capacitor will stay same, because the charged battery will lose the potential energy across the resistor, but the circuit is an open circuit, the potential energy does not lose. Since, it is stay st same.
Experiment set up:

In the experiment, our predict is acceptable. But during the measuring, we found it is not perfect march because some of  potential energy from the capacitor is restored by wire.

Activities: Calculation of unknown capacitor:

 With the equation Ae^(-ct) + B，a best fit line is made for each of the graphs. The relationship between potential/voltage and time for a charged capacitor can be conclused VC=Vmax (1-e*(-t/RC)) and for a discharged capacitor it is VD=Vmaxe^(-t/RC). In our lab, the initial voltage is not correct because we do not start from 0. So when LoggerPro tries to do best fit line, it does not start at the right time.

Day16

 Find the Permeability of Paper of k constant by controlling the the Capacitance and separation of distance.

Set up: we use two pieces of Al sheet, and to make them parallel by putting them into the pages of book.  Then, we took multiple measurement by changing the separation of distance.

 According to the realistic value provided by Professor Mason, We have huge error and uncertainty in this lab. The error could be caused by the different pressure we apply to the book.

3. Experiment to burn down a capacitance. Be aware: that never connect it the wrong way.

In most practical applications, each conductor initially has zero net charge and electrons are transferred from one conductor to the other; this is called charging the capacitor. Then the two conductors have charges with equal magnitude and opposite sign, and the net charge on the capacitor as a whole remains zero. 

Day15

1. circuits:

Set up: Professor Mason shows us a diagram of electric circuit, and let us guess with light bulb will be lighter or same?

Result: Top and Bottom: same brightness.

             Center:                do not light up.

Set up: Professor Mason shows us other diagram of electric circuit, and let us guess when the switch is closed, the light will be darker, lighter, or same?

Result: same brightness

2. series circuit : set up a series circuit, so connect two light bulb together. An ammeter is used as a wire

3. parallel circuit : set up a parallel circuit, connect each light bulb to battery. A voltmeter is used to measure the voltage for all light bulb.

4. measure the resistors :

In the this experiment, professor Mason gives each group 3 resistors with different color, and let's measure and calculate the value of resistor. Then, we also calculate the different percentage for all of them.

Day14

Calculate the work done when the charged is particle on the electric field of the rod:

Calculation of the potential energy :

The surface of tow opposite charged particle:

Electric Potential Lab/Activity:

Experiment set up:

Part 1:

 Question 1: 15 voltage means that the power supply gives 15J/C potential energy to the system.

Part 2:Data; Excel table and graph:
The data of the voltage and calculation of change in V/change in x is collected below. Also, the calculation of work done from x=0 to x=3. x=4 to x=6, and x=5 to x=2 also calculated in the spreadsheet.

Graph: Potential vs Position 

Day13

1.Dim/Bright Circuits:

1. Set up a circuit that have the dimmest possible brightness of the light bulb, and another circuit with the brightest possible of the light bulb.

In a series circuit, the light bulb should be  dimmest because in a series circuit, the light bulb's net voltage equals total voltage that the battery has. It means each light bulb has lower voltage. But in the parallel, each light bulb has the voltage is equal to the battery, so it means in the parallel, the voltage is higher than the voltage in the series. Since, the light bulb in the parallel is brightest.

 Ohm's Law:
Experiment set up:
 Set up a power supply (able to change current and voltage) to inside a cup of water. To raise up the voltage and current to heat up the water in the cup. And record the changing.

Then, we calculated the theoretical value of final temperature of water can be raised by putting recorded voltage(hot, energy) into the water.

We calculated the theoretical value of final temperature of water is 53.2, but in the fact, the temperature is 43.1. This error is caused by changing in voltage and current. And during the heating, the some of energy and hot has already lose. Since, the true temperature is lower than the theoretical temperature.