This is an oscilloscope. In the tube, a heated filament and a series of accelerating and focusing electrodes serve as the source of a well-collimated beam of
electrons, which cause a beam of light.
This is the inside view of an oscilloscope.
Proof that Deflection is Proportional to Voltage
Some derivations for an electron traveling through two plates.
Sounds from a Function Generator
This is a function generator. We are going to use it to generate several different waves. Professor Mason is showing us how a speaker works. To do this experiment, we first plug in and turn on the function generator. We turn off the DC offset. We then connect the
cable with the clip leads to the a low voltage output. We set the function generator to produce a 96-Hz sinusoidal wave by
setting the frequency multiplier to 100 and adjusting the dial appropriately. Finally, we attach the two output clip leads from the function generator
across a speaker.
Our set up for this experiment.
From this experiment, we know that at 96 Hz, we only hear a low pitch constant sound. When we change the function of a wave, we hear different sounds. Triangle is close to a sin function, while a square produces a loud constant sound. When we get a higher frequency, we get a high pitch sound. When the voltage gets higher, the volume also gets louder.
Wave of the function as a sin function.
Wave of the function as a square function.
Wave of the function as a triangular function.
We play with the oscilloscopes, the power controls the brightness. The focus controls the diameter of the light.
Calculation of the period shown in the Oscilloscope: The frequency is calculated to be 92.5 Hz. It is close to the theoretical value.
Different Shapes of AC power supply since the current is changing directions all the time, and the voltage is not constant.
Different Shapes of AC power supply since the current is changing directions all the time, and the voltage is not constant.
Different Shapes of AC power supply since the current is changing directions all the time, and the voltage is not constant.
Different Shapes of AC power supply since the current is changing directions all the time, and the voltage is not constant.
Different Shapes of AC power supply since the current is changing directions all the time, and the voltage is not constant. 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.
Example of how we measuring the voltage and whether it is AC or DC.
Using the oscilloscope, we can find the frequency, time and voltage. The value makes sense.
Results of a Mystery Box
Summary:
In today's lab, we learn how to use a oscilloscope.
For this lab, we are given two capacitors that are 1 mF each. We are going to find the total capacitance in parallel and series. But first, we need to find the actual value for the two capacitors.
We get the value of 0.994μF and 0.984μF.
We then put them into series.
The capacitance is 0.489μF.
We then put the two capacitors in parallel.
The capacitance is 1.978 μF.
From these values we can find a relationship between capacitors in series and in parallel.
In series, the relationship of total capacitance of capacitors is 1/Ctotal=1/C1+1/C2.
In series, the charge is the same for the capacitors and so when looking at V=Q/C, the charge can be ignored and the only variable left is V.
In parallel, the relationship of total capacitance of capacitors is Ctotal=C1+C2.
In a parallel circuit, the voltage is the same for the capacitors and so when looking at the equation Q=CV, voltage can be ignored and only variable left is C.
Charge Build up and Decay in Capacitors
The graph of a circuit which is the same as our lab set up.
For this lab, a capacitor is first charge. Then, we will show how energy is used from it.
This is the experiment set up.
From the video, we can see that at first the light bulb lights up. Then, the light goes dimmer and dimmer, and eventually it goes out, because it is charging the capacitor now.
Then we connect the two wires together to build a closed circuit. The light bulb turns on again, and it goes dimmer and dimmer, and eventually turns off. When the wires are removed from the power supply and the circuit is closed, the bulb is being powered by the capacitor.
This lab shows us how the capacitor works, it is first charged and stores the power. Then it is discharged by charging the light bulb.
A Capacitance Puzzle
In this lab, we first charge the two capacitors, one is at 3.0 V and the other one is at 4.5 V. The charge will reach equilibrium and that can be found by finding the average charge of the two capacitors. The next step was to find the new voltage of two capacitors in parallels. Because the capacitors are in parallel, the capacitance adds up and we get a total capacitance of 1.12 F. The voltage is found by the formula V=Q/C and is calculated to be 3.75 V. Using the voltmeter, the capacitance was calculated to be 3.67 V. This amount of error can be due to the capacitors we use. The capacitance may not be the same as what we see on the cover. Also, the charges may discharge somewhere. Overall, our calculated value is very close to our theoretical value.
Quantitative Measurements on an RC System
For this lab, we do more quantitative measurements on a RC system.
This is the set up for this experiment.
Our goal is to find a mathematical relationship between voltage across a capacitor and time that describes how voltage changes as the capacitor discharges.
First, we measure the voltage across a charged capacitor . A current meter, LoggerPro and a resistor are also attached to the circuit. From Logger Pro, we get a Potential vs. Time graph and a Current vs. Time graph is made. As seen in the LoggerPro graphs below, there are four graphs; potential and current graphs for with voltage and potential and current graphs for without voltage.
A best fit line is made for each of the graphs with the equation Ae^(-ct) + B. It can be concluded that the relationship between potential/voltage and time for a charged capacitor is VC=Vmax (1-e*(-t/RC)) and for a discharged capacitor it is VD=Vmaxe^(-t/RC).
In our lab, the voltage initial 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.
Summary
In today's class, we learn how to calculate the total capacitance of capacitors in series and parallels. And we learn how a capacitance change in a capacitor as time changes.We also learn how a capacitor works.
Professor Mason is showing us what is inside the battery. It is just two different sheet of metals.
Here are two capacitors.
This is a small capacitor
The derivation of equations and units.
The derivation of equations
Blowing Up a Capacitor
2. Permeability of Paper
The set up of the experiment. We should try not to let the two Al sheet touching each other.
In this lab, we use aluminum sheet to find the permeability of paper. We connect a multimeter to the pieces of aluminum sheets separated by several numbers of sheets of paper. We measure and record the capacitance. We can find the area of the cross area by finding the dimensions of the sheets of aluminum, We can take several pages of paper, measure its thickness and divided by its pages to measure the thickness of one page. With the area, distance of paper, and capacitance, the K value can be found. We see that as the distance between the sheets of foil increases, the capacitance decreases and K value decreases.
Summary:
In today’s class, we learn how capacitor works and different kinds of capacitors. We learn how to find the permeability of paper also.
