Electronics: Analog and Digital Oscilloscopes

With an app downloaded on a phone which was then connected to an oscilloscope, we used it to visually see the sound waves emitted by the phone. At certain hertz, we were able to see the different types of waves that is emitted. As the hertz level was raised, the higher the peaks of the waves.

We now turned on a song to see what the oscilloscope would display and it displayed sharp and fast waves.

We then connected to the circuit the speaker to see if the speaker would emit the song.

Although the oscilloscope was displaying that the circuit was connected well, the speaker was not working properly. It may have been a circuit problem within the speaker or our wires were not connected properly.

Next, Professor Mason provided us with some bread boards and a red light bulb. He told us to build a circuit with a capacitor to light up the red light bulb.

The little holes are connected to each other in a column and with some extra circuit wires and an external battery, we were able to light up the red light bulb.

This is an overhead view of the circuit. We were also given a resistor to add the circuit.

The capacitor acts like an on and off button for this circuit.

This is the capacitor.

This is what we had to work with. The external energy source and speakers were connected but not turned on. The box contained the extra wiring we may have needed.

We tested the condition of our bread board by connecting it to the oscilloscope.

Something was being emitted..

This was the end result of our bread board.

At last, we connected it to the external energy source and speakers and as we pressed the capacitor button, the speakers were able to emit music with much difficulty.

Circuits: Capacitors

These are the steps for Kirchhoff's Law. Because we do not know the direction of the current, for now, we guess. If our answer turns out negative, then the current goes in the opposite direction.

This is the Kirchhoff's Law in practice with an example problem. The law also states that I_1 = I_2 + I_3.

Another equation that is part of the law is Voltage - I_1*R_1 - I_2*R_2 = 0.

Next, Professor Mason introduced us to capacitors by showing us what is inside of one. There is a long film that stores all of the electrons and it is also wet to preserve the electrons. Once it goes dry, the capacitor no longer works efficiently. The solution that keeps the film wet is a dielectric.

These are the components of a capacitor.

These are the different types of capacitors displayed here. Each one has a different strength as well.

The green one is called a super capacitor and is the strongest capacitor available. Although small, it is quite heavy.

Below is an equation to evaluate the strength of a capacitor. C is the dielectric constant kappa times initial epsilon times the area all divided by a distance. The unit of measurement of capacitors are called Farads.

In this next activity, Professor Mason blows up the capacitor below to show the extent of its limit.

Below, we derived the electric field equation to find out how much charge is stored in a capacitor.

We have spoken about the constant for permitivity of free space but what are its units of measurement? Using the capacitor equation that we derived above, we were able to find them. Epsilon's unit of measurements are a Farad over a meter.

Next, we measured if capacitance depends on area or on separation by using a textbook, two sheets of aluminum foil, a multimeter, and a vernier caliper.

Utilizing the capacitor equation found before, we were able to determine the dielectric constant for paper. We also found that all of the units cancelled which made kappa a unit less variable.

The number displayed on the multimeter is the capacitance that was measured. We found that there was no possible way for it to stay constant long enough because of the pressure that was being applied by one of our group members.

We then continued to calculate the dielectric constant with different amounts of paper. But because it was difficult to find a constant capacitance value, it was difficult to determine whether the capacitance was indeed dependent on area or whether it was dependent on the separation.

Rearranging the capacitance equation, we were able to find the distance between the Gaussian surface and the capacitor with the given values. With that, we were then able to find the density.

We were also then able to find the charge inside the plates as well as the magnitude of the electric field using the kappa found earlier.

We were told that 20 horsepower was charged inside the plates of a capacitor for five hours. We were then asked to find the actual capacitance of the capacitor when the voltage was at 400.

With the equations shown below, we were asked what the relationship between kappa, capacitance and sigma was. We found that as kappa increases, then C will increase and thus, sigma will also increase. And what about voltage? Well, voltage, V, will decrease which results from: V = Q / C.

Circuits: Resistors

Below, Professor Mason is holding up a circuit board that he created. There are three light bulbs and two sources of voltage. There is also one switch. He asked us what would happen if he were to close the switch.

This is our prediction. We predicted this because we thought if the switch was closed, the three bulbs would then have to share the voltage sources.

Professor Mason then presented us with another circuit board. There are two light bulbs and three batteries except one is separated by a switch. He asked us then what would happen if he closed the circuit.

This was our prediction with explanation.

This was the actual result. Because the batteries were placed in series, there was no potential change.

We were then introduced to these little resistors. This is the inside of a resistor because Professor Mason had cut one in half.

On a resistor, there are four colored bands a person would look at to determine the strength of a resistor. Though the first one is not of our concern at the moment. Each color represents a value from 1 through 10. The general equation used to calculate the strength is AB*10^C. A is the second color, B is the third and C is the last.

These are some resistors that were in the lab. Each one has a different set of colors.

We were then asked to calculate the strength of three different resistors and to calculate the percent difference.

Using a multimeter, we were able to calculate the actual of each resistor. The value on the mutlimeter was off even with the given number because of the first color on each resistor. That color represented the percent error in each one.

This is a resistor set up in series. With this set up, the strength of it went up.

This is a pair of resistors set up in parallel.

And it turns out that the parallel set up makes the strength weaker.

These relationships is defined in two equations. When resistors are in series, we merely add the resistors together: R = R_1 + R_2 + ... R_n. If the resistors are parallel, the total is the addition of the resistors inverted: R = 1 / (( 1 / R_1) + ( 1 / R_2) + ... ( 1 / R_n)).

This is the value of three resistors in parallel.

Another set of three resistors in parallel.

The method of calculating the resistors on a circuit is by evaluating the ones in series first, then parallel. So below, we calculated the series resistors first to be 200 ohms, then the parallel relationship to be 66.67 ohms and the total of the resistor circuitry to be 166.67 ohms.

However, due to the uncertainities in each one being added as well, we were not precise. The actual relationship was 149 ohms.

Another example of an actual reading of the same set up.

As an introduction to Kirchhoff's Law, we calculated the currents and voltage of a given set up of a circuit board that included resistors. Kirchhoff's Law has us calculate the different variables by determining which ones are in which loops.

Current Flow

How do batteries work? On a battery, there is a positive end and a negative end. Electric current runs from the negative side and into the negative side. The potential that is created through the wiring causes anything connected to a battery run. Using a battery and some open wiring, we were able to light up a small light bulb. One way that worked is by putting one end of the open wire on the negative side of the battery and connecting it to the positive side where there was also a light bulb. When connected, the light bulb lit up.

Below are some quick videos of electric fences which represented the different amounts of electric potential at different heights.

Using Logger Pro, Professor Mason was able to measure the different currents that ran through the wires.

Below is his set up of circuits. The red box is an older version of a voltmeter, which measures the voltage running through a circuit.

Electric Potential

To find the electric potential between two charges, we mapped the potential with electric paper, probes connected to a voltmeter, and two dots on the paper to represent charges that are charged by an external power source. The charge on our left was chosen as our test charge. Below is the activity.

This is the graph that we produced after finding the different amounts of potential between the charges. We first began the activity with both probes on our test charge. As one probe went closer to the other charge, the electric potential went up. When the probe left the second charge and continued its path, the change of electric potential became more gradual.

Looking at our graph, the electric field is going in the positive x direction because we are going from low potential to high potential.