Day 26

In this class, we learned the RLC circults. In a RLC circult, it connects resistance, inductance, and capacitor. And we do a problem First the resonance frequency was found. Then the current was found at a resonance frequency of 3 kHz. Afterwards the power dissipated at that current was found. We use Pavg because power is stored, not dissipated.

Resonance in RLC Circuit

An RLC circuit was set up, the theoretical resonance frequency can be solved by using values of the inductor and capacitor found with the multimeter. And we use the function generator to find the experimental resonance frequency

In the part two, the experimental impedance was found by the measured values from the multimeter, from the formula Z=((R^2 + (Xl-Xc)^2)^1/2. Finally that value was comparedto the theoretical value of impedance; Z=R.

In part three, the theoretical frequency and experimental frequency were found using LoggerPro. As we can see on the graph, there is a phase angle difference of 180 degrees. If the frequency was increased, the amplitude decreases when measuring across the capacitor and the amplitude increases when measuring across the inductor.

When we increase the frequency, amplitude decrease when measure capacitor. And amplitude decrease when measure inductor.

Transformers

 A transformer is made by making two inductors together by two coil. The coil redirects magnetic flux in one inducto to other one, then other one produces a field too, so that the second coil will produce a current. Since, the second coil produce a voltage and gain energy. from first coil.

Day 25

Resistors in an Alternating Circuit 

When we are studying the  Alternating Circuit, we connected the function generator resistor and current meter in series. The potential vs. Time, Current vs. Time, and potential vs Current .

 Capacitors in an Alternating Circuit 

When studying a capacitor in an alternating circuit, the same set up from the resistor was used expect now the resistor is replaced with a capacitor. In AC circuits, capacitors exhibit a resistance. 

Inductors in an Alternating Circuit

When we are studying Inductors in an Alternating Circuit, we used the same set up as previous part except now we are replacing a capacitor by inductance in an AL circuit. Then we collected data and graphs from LoggerPro.

In the final part of the lab, a RC cirtuit in AC was studied. A resistor and a capacitor was hooked up to a function generator and a current meter and volt meter were connected to LoggerPro. Using the graphs the Vmax and Imax were found and the Vrms and Irms. The total resistance within the circuit is the total impedance, or Z.

We then calculate the percent difference for the impedance as well as time phase change. 

Day 24

The formula about L(Inductance)

Inductance was studied through ActivPhysics. Questions 1-8 were answered. 

In this lab, we set up a circuit with containing a function generator, a resistor, and an inductor. At the same way, a voltmeter was used in order to help us to find the voltage across the resistor and inductor. All data gathered was recorded on the white board photo below. 

Day 23

Force Due to a Magnetic Field 

In this experiment, we did two experiment. First one, when two wires with same direction current, they attract each other. Second one, when two wires with different direction, they repel each other. Because two same direction current both produce field, and in the mid of two wires, their field is opposite, so they attract each other. However, in the opposite current, in the mid of the two wire, the field is same direction, so they repel each other.

In this experiment, a solenoid is used to check field. And in the experiment, we use a test tube with wire loops with current, so that the test tube produce field. Then, we move the test tube with current to close the solenoid and record the largest field value. In the same way, we increase the number of loop, and find the max field value.

 

Lenzs' Law
Changing Field produces current

In this experiment, professor mason use a magnet go though a coil. And we connect an amperemeter to the coil. During professor use the magnet go though coil, we see the amperemeter's Pointer moves. When the magnet goes though the coil, the field to the coil change, so the coil's field changed, then field produce current.

 In this experiment, professor mason, thrown two magnet into two hollow stick, aluminum stick and plastic stick. Professor mason drops then at same time, but we find the magnet in the plastic out early. In the aluminum, the magnet out later. Because when magnet fall in the aluminum stick. The aluminum stick produces a field against the magnet's field, so a force push magnet back. After the magnet leaves stick, a fore that attract the magnet is produced.

5% extra credit

To remind and help teams who takes part in match

Day 22

Changing thumbtack to get magnetic, and use 2 ways to destroy it.

  In this demo, Professor Mason has two coils of wire that can become magnetic when it is connected to a power supply.  A switch is attached to the two coils to change the direction of magnet. When the switch is on, the magnet oscillate. When the magnet is in parallel with magnetic field, the torque is zero. When the switch is on or off, it oscillates and stop. In order to keep the magnet spinning, we need to keep switching it to on and off. 
  2 pole vs. 3 pole
In a two pole motor, it can stop and get stuck but with a 3 pole motor, there is always some torque and that is why most motors are made with an odd number of poles. 

Motor:
Next we build a motor by getting the tool from professor Mason.

After we build the motor, we start to supply power. When power supply is applied, the motor turns one way. When the power supply is reversed, the motor turns another way. 
Forces on a Line of Charge :In this activities, we interpreted the magnetic field by using the right hand rule. When we are doing at the top, nothing happens to the magnetic field because the two currents are canceling out, current going up and current going down. When we go to the area on the right hand side, there are two currents going in the same direction and it gives double the magnetic field. When you go to the area in the middle, there is a magnetic field going through the center of coil. 

Compass and Magnetic Demo:

When a current goes to top, it will make a  magnetic field to around with a center. When the direction of the current is switched, the arrows change directions as well. This demo proves a rod of current has a circle of magnetic field. 

Day21

No class today. No lab today. ☺

Day20

Magnetic Fields:

By using a compass, we can find the direction of a magnetic from a bar magnet, North is attracted to South, and south is attracted to north, too.  Drawing the direction by compass.

 Gauss's  Law in Magnet is defined as ∫B∙dA. ∫B∙dA=0 because there is no monopole, in every single magnet, there will always be south pole and north pole. Thus, the net flux is always zero. 

  Electric Field Lines:
After using compass, we spray some Fe power near a magnet to see the magnetic field. Magnetic fields go from positive to negative. 

Lorentz Force

Lorentz Force Large Magnet Demo

For this lab, Professor Mason shows out a large magnet and set up a copper wire across and in between the magnet.

When we give the current, we found the copper wire jump down, but when we change the direction, the copper wire jump up.

The velocity of the electrons is going through the wire, the direction of the magnetic field is going across the poles of the magnet, and the force is perpendicular to the velocity and magnetic field (Lorentz Force= F=qVxB or F=qvBsinθ).

 Finding Net Force

we find the total force on a wire by using a spreadsheet. (F= IL x B) It can be observed that there is a maximum first at 90 degrees and a minimum on the sides. 

Day19

 Analog and Digital Electronics:

For this lab, we connect our phone to with the oscilloscope and a speaker, and we download the tone generator app to help to find the highest frequency that a phone can put out through the music.

 When we played two songs, the wave we see:

In the this lab, we built the LED light circuit on the circuit board. When the power supply is on, the LED light is on. But some we find the LED light is off because LED light is a diode, when we put the power supply backward, the LED light will remain off. 

Low Pass filter:
For the low pass filter lab, a circuit is set up by using a 0.1 uF capacitor, a 22K resistor, 2.2Meg, 3.3K resistor, and 0.22uF capacitor. The circuit was connected to the oscilloscope and with the tone generator app. we could find that resistors are not frequency dependents and capacitors are.