RLC Circuits in AC cont.

The day began with a little surprise for us early birds. Professor Mason gave us an idea of what was going to be on the final exam. Pretty much what is shown below is what the exam would cover and we also went over V (rms) and I (rms) again but this time involving the variable Z which equal root (R^2 * Xc^2) and then we solved for I (rms) by itself and substituting 1 / 4*omega^2*C^2 for Xc^2.

We then did some more activities involving RLC circuits as shown in the graphs below showing Current vs Time and Voltage vs Time.

We also did a cosine fit for both of the graphs since both were AC circuits and the voltage and current oscillates until it reaches a maximum and minimum value.

Using the graphs shown above we were able to finish the table shown below recording what would happen to the flux if the frequency was increased so we tried the experiment with 3 different frequencies which were 10 Hz, 100 Hz and 1000 Hz. We compared the values from the theoretical values and got high error percentages but it was probably because Mason guestimated again.

We then moved on to an ideal AC circuit problem having a resistor, capacitor and inductor. We were asked to find the frequency, the current value and the average power of the circuit.

We ended the class by having to find the frequency of another one of the RLC circuits. Our calculations are shown below.

Overall, the class dealt with the final part of the RLC circuits in AC and solving some more simple problems involving these different values.

AC and RLC Circuits

The day began with an introduction to AC circuits and RLC circuits and finding how current and voltage behave throughout using Logger Pro. The result of the graph we acquired is shown below.

The introduction to AC circuits are shown below on how we get the root mean square voltage and how it can be used to solve for the voltage needed in an AC circuit.

The set up of how the R circuit in AC looked like is shown below.

Using the information about AC circuits that we had just learned and using the graph from Logger Pro, we were able to find the needed values to fill in the table below.

We then moved on to the behavior of the voltage and current in a perfect AC circuit as shown in the hand-drawn graph below. We also did some more calculations regarding root mean square values of current and voltage.

We then moved on to a circuit in AC involving a capacitor. The graph of what the voltage and current looked like is shown below. The set up was pretty much the same as an R circuit in AC but with a capacitor hooked up.

The results from our data is shown below.

We also did some more problems with AC circuits  involving frequency, inductance and finding the value of X sub L.

We finally moved on to a complete RLC circuit within AC. The table of our values are shown below.

The set up shown below included everything connected in series.

The graph from Logger Pro is also shown below and shows how the current and voltage still oscillate when in AC.

Overall, the main focus of the class was to see how the current and voltage behaved in AC and how putting each of the components including capacitors, resistors and inductors affect the outcome of the voltage and current.

Inductance Continued and Current Flow Time in an Inductor

The day began with an ActivPhysics activity 14.1 called The RL Circuit. It was a circuit with resistors and inductors. We began solving some problems until Mason told us to stop because he thought we had done it before (which I do not think so) and so we moved on to another RL circuit which dealt with a closed circuit involving resistors and inductors with a switch and a 45 V battery. We solved for the torque of the inductor, voltage and current at the different points of the resistors and inductors. We also talked about how long the inductors would take in order to charge fully and how long they would take to charge to a certain point.

Using a previous 110 turn inductor (for which we calculated the inductance of) we tried to see whether our measurements could result in almost the exact amount of turns which it did not as seen below because we assumed many of the variables (which we always do haha).

Below is a picture of the set up we had in order to measure the current output made by the function generator and the closed circuit shown in the next picture. The waves indicate that the current reaches a certain point and then it it looses charge and then it repeats but I do not believe we got the correct function.

Below is a picture of our set up and how we connected the whole thing in series except for the resistor because that was in parallel with the inductor.

After Mason helped us out, the function shown below is what the actual outcome should be showing that as current goes through the charge reaches a maximum point and then resets every time a current goes through.

Below is a picture of the new set up that actually worked for us.

Next we talked about inductance and solved some more problems regarding inductance involving finding certain variables like resistance, inductance and the period of it.

Overall, the main emphasis of the day was to sharpen our skills regarding inductance and also the time it took for an inductor to reach max capacity.

Change in Direction of a Magnetic Field and Inductance

The day began with an ActivPhysics activity regarding magnetic fields and what increasing or decreasing variables would do to the overall results. We played around with a little graph where we changed the variables as well and we saw how the graphs of magnetism and force changed as we also increased or decreased variables.

Professor Mason then showed us what would happen to a magnet if current was turned on within the rod found in the picture below. He made us guess whether it was going to roll away or towards the magnet if the direction of the current was changed.

Below is a picture where Professor Mason asked us to predict how the force, magnetic field and current were behaving in the model above. Our results are shown in the picture below.

We then did another ActivPhysics activity regarding magnetic flux and how current direction affects the outcome of the magnetic field. We also related the flux between electric field and the change of area is equal to the charge over the constant epsilon not. We related that equation to the magnetic force one and found that the charge times the electric field plus the charge times the speed cross the magnetic field.

We then moved on to the topic of inductance defined by the symbol L. We found that the equation for inductance is mu not times the number of turns squared times the area all over the height of the coil.

We also solved an inductance problem within a closed circuit and was able to find the potential of the inductor.

Lastly, we did another ActivPhysics activity and then we decided to call it a day.

Overall, the main focus of the day was how the direction of the current affects the magnetic field and we also learned about inductance and inductors as well.

Magnetism Continued

The day began with a little exercise regarding the direction of the force with regards to a current carrying wire going in the up direction. We then talked about the magnetic force in relationship with current and magnetic field. We also drew a graph of what the magnetic field with respect to time would look like.

We then examined how the magnetic field would look like using Logger Pro and we got a resulting graph shown below.

Mason then did an experiment of how a magnetic field could lift up a uniform ring depending on the density of the ring.

We then tired to draw an example of how the field was supposed to look like and how the current as well as the magnetic field were directed. We also drew some more relationships between current and the magnetic field.

Lastly, we were supposed to predict how the emf and magnetic field were supposed to look like given the graph of the magnetic field.

Overall, the main focus of the day was to draw some more conclusions toward the magnetic field of a current and then draw some predictions on how if plays in different scenarios.

Magnetic Fields and Torque

At the start of class we recapped on what the magnetic field of a magnet looked like and Mason also asked us to find different ways to demagnetize a magnet. Professor Mason also added that the reason why the magnet has that type of magnetic field is because of the structure within the magnet. Using that knowledge we chose to change the shape of the magnet because the structure would change and therefore the magnetic field would not exist anymore. Temperature could also alter the magnet's magnetic filed because a change in temperature also changes the structure of the magnet but slowly.

After talking about how a magnet worked, we reviewed a little of the previous magnetic field concept acting on a closed circuit. We examined how the force would work and what it related to. We used our previous definition of torque and using the force we were able to get the torque of a magnetic field which was equal to half the length squared of the current times the magnetic field times the sine of the angle between them. Using that knowledge we were able to solve our problem using the concept we just learned.

Next we were asked to created our own motor using magnets and allowing the motor to run for a long period of time. The picture of the apparatus is shown below.

We tried different scenarios by switching the positive and negative side when powering the magnetic motor. We found that it spins counterclockwise when the positive is on the north side and clockwise when the negative is on the same side.

Lastly, we applied magnetic torque to a sphere and solved a problem and we also tied the idea of current but using a different definition to magnetism and after that Mason showed us an experiment on how compasses behaved when a magnetic field was present.

Overall, we learned more about magnetic fields and the concepts behind torque and we went more in depth regarding magnetism.

Magnetism and Magnetic Fields

The class began with Professor Mason holding a bar and a compass. Then he showed us that when the compass came into close contact with the compass it no longer pointed just north. He then asked us to get a magnet and put it on the board and put the compass around the magnet. Then he asked to draw the direction that the compass arrow pointed. The picture of what we got is shown below.

After finding out that the arrows in fact made a magnetic field which was made by the magnet we were to draw the lines of the magnetic field. The picture of what it looked like is shown below.

We then moved on to the topic regarding magnetic flux. Professor Mason gave us the relationship between magnetic field and area as well as the angle between those two vectors. We were also able to draw the direction of each of the components for Force, Magnetic field and voltage using the right hand rule.

Professor Mason also showed us how the directions of the fields we drew were applied to an actual wire.

Here is a video of how it was supposed to look like.

We later moved on to applying previous definitions in order to find the relationship between force, current, mass, velocity, frequency and current. 

Lastly, we talked about the effect of a magnetic field on a circuit and found that the force was perpendicular to the current and we also observed how a spin on the magnetic filed would affect the current which is shown in the picture below.

Overall, we were introduced to magnetism and how a magnetic field would affect force and voltage and we also linked the concept of magnetism to previous concepts we had previously learned.

The Oscilloscope and Function Generator

The day began with Professor Mason telling us that the day was going to be spent using an oscilloscope and we were going to use it to determine relationships between graphs and sound as well as learning how to use the oscilloscope and function generator. The picture below shows that of the oscilloscope our group used during the day.

Mason also showed us some relationships between the electrons present within the beam of light and how it shifted if a magnet was used. We also reviewed some electrical key concepts and applied them to the oscilloscope.

First we were asked to use the function generator (the machine above the oscilloscope) and change the different function, amplitude and frequency settings while connected to a speaker and hear what different sounds it made.

The question regarding the different sounds they made were answered in the space below. We found that at 96 Hz, the speakers emitted sound like radio static and that a triangle function gives the lowest amount of sound while a square function gives the loudest sound and a sine function gave sound in between those two ranges. We also found that as the frequency increases, the sound gets sharper.

To finish the sound portion, we also found that as amplitude increases, the sounds gets louder. 

We then moved on to some of the oscilloscope controls and played with some of the controls. We found that by changing the intensity, the brightness of the line changed as well. The focus control allowed us to see the line clearly and not too thick nor too thin. Lastly, the time controls changed how fast the light inside was moving depending on the different outputs of the function generator.

Next, we attached a battery to the oscilloscope in order to measure the steady voltage of the battery. We found that as the current flowed, the light moved from one side to the other in a straight line indicating that the voltage was constant. We also saw what adding a tap key to the battery would do and we saw that it changed the scale on the screen every time it was moved from on to off.

Below are just examples of the different outputs made by the function generator.

We also used the power output in order to see whether our voltage reading was correct which it was very close to.

Lastly, we had to use our knowledge of operating the oscilloscope and predict what type of current was being emitted from the mystery box. Our results are shown below.

The main focus of the day was to let us teach ourselves how to operate an oscilloscope and use a function generator and see how different scenarios affected the functionality of the machines.