lab 09 PHY 112
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Rio Salado Community College *
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Course
112
Subject
Astronomy
Date
Apr 3, 2024
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docx
Pages
6
Uploaded by CountWombat1912
PHY112 Lab 9
Name: Radio Waves
Section: Download and run the PhET Radio Waves and EM Field
simulation. Use the simulation to answer the following questions.
1.
Select the following simulation settings: manual, full field, electric field, and static field. Record your observations. Move the electron down the antenna. Record your observations.
Move the electron back to its starting position. Change the setting from static field to radiated field. Record your observations. Move the electron down the antenna. Record your observations.
Change the simulation settings from manual to oscillate. Record your observations.
Analyze your observations, and draw some conclusions based on this information. Record your conclusions in the last row on the data table. Settings
Observations (be specific and detailed)
Static field, motionless
electron
An electric field is shown around the pole facing towards the electron. The electron is surrounded by a static field, and the field lines point towards the electron. Closer to the electron, the field lines are represented by large arrows, while the become smaller as they move farther away from the electron.
Static field, move electron
down the antenna
When the electron moves within the field, the arrows follow the electron down the antenna. There are more large arrows surrounding the electron as compared to when it is at rest.
Radiated field, motionless
electron
The arrows disappear. In a state of rest or when not in motion, there is no observable radiated field present. Radiated field, move
electron down the antenna
As the electron moves through the field, the field lines represented by large arrows point away from the electron. As the field radiates outward from the electron, the arrows change direction and diminish in size. Radiated field, oscillating
electron
As the electron oscillates within the field, it emits a continuous
radiation. The directional orientation of the field lines, depicted by arrows, undergoes consistent changes as they extend further from the electron. Conclusions
In a static field, the field lines always point toward the electron, regardless of whether the electron is at rest or moving downwards. The radiated field is only present when the electron is in motion, and in this case, the field lines point from the electron.
2.
Select the following simulation settings: oscillate, full field, electric field, and radiated field. Switch back and forth between the force on electron setting and the electric field setting. Pay particular attention to the receiving antenna electron. Complete the following table by filling in either up, down, or zero for the directions.
Analyze your observations and draw some conclusions based on the observations. Record your conclusions in the last row on the data table.
Position of electron in
receiving antenna
Direction of force on electron in
receiving antenna
Direction of electric field at
location of electron in receiving
antenna
Maximum
down
up
Minimum
up
down
Equilibrium (halfway
between max and
minimum positions
zero
zero
Conclusions
The relationship between the direction of force and the direction of the electric field is such that they are inversely related. This means that when one direction changes, the other direction changes correspondingly in the opposite manner.
3.
Select the following simulation settings: manual, full field, electric field, and radiated field. Run the simulation long enough so that there are no EM waves on the screen. Check the box for electron positions. Change the simulation setting from manual to oscillate. Let
the simulation run for a bit, and then pause the simulation. Answer the following observation questions:
Question
Answer
Do the transmitting and receiving antenna electrons start moving at the same time? If not, which one moves first? When does the other start to move?
No the transmitting electron begin moving right away and the receiving electron does not start moving until the arrows reach it.
When the transmitting electron is at its maximum position, where is the receiving antenna electron (e.g., max, min, zero, or some other position)?
When the transmitting electron is at its maximum position, the receiving antenna electron is also at its max.
Compare the time that it takes the transmitting electron to complete one full cycle of motion to the time it takes the receiving electron to complete one full cycle of motion.
The transmitting electron moves faster and completes one full cycle quicker than the receiving electron moves and completes one full cycle of motion. Compare the distance the transmitting electron travels in one full cycle to the distance traveled by the receiving electron during one full cycle.
It seems like the transmitting electron also moves further than the receiving electron.
4.
Use your observations in tables 1, 2, and 3 to explain the motion of the electron in the receiving antenna. What causes it to move? Why does it change direction? How is this motion related to the electron in the broadcasting antenna? Be specific and detailed. Use your observations to support your discussion.
5.
Select the following simulation settings: oscillate, full field, electric field, and radiated field. Let the simulation run long enough for the receiving antenna electron to begin oscillating. Pause the
simulation. Take a screen shot. Paste the screen shot into the space below.
The electromagnetic waves causes the motion of the electron in the receiving antenna and in a way mimics the same motion but slower than the transmitting electron. We can see it changing directions because of the transverse oscillations from the transmitting electrons. Like said earlier, the receiving electron is imitating the motion from the electron in the broadcasting antenna. The receiving electron moves slower and covers less amount of distance than the transmitting electron.
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Answer the following observation questions based on the above picture. Observation question
Answer
Roughly, how many electric waves are present in the above picture? I see around 5 electric waves present in the above photo.
How could you use this electric field diagram to determine the length of the electric waves?
We can determine the length of the electric waves when it changes the arrow direction. 6.
Change the setting from full field to curve with vectors. Switch back and forth between force on electron and electric field settings. What does the curved line in the curve with vectors setting represent? Explain your reasoning.
The line remains consistent regardless of adjustments made to the field settings, whether concerning the force on the electron of the electric field. I think the curved line illustrates how an electron responds to the electromagnetic field, as it moves in the opposite direction to the broadcasting electron. This inference aligns with the principle that like charges repel each other.
7.
Select the following simulation settings: oscillate, curve with vectors, electric field, and radiated field. Make the following changes, and observe the effect the change has on the wavelength, frequency, and amplitude. Also, observe how this change affects the behavior of the motion of both the transmitting and receiving electrons.
Reset the simulation between each system change (e.g., set the frequency back to its original position before changing the amplitude). Record your observations.
Analyze your observations, and draw some conclusions based on the observations. Record your conclusions in the last row on the data table. System
changes
Effect on the
wavelength
Effect on
number of
waves
between the
antennas
Effect on wave
amplitude
Effect on
transmitting
electron
behavior
Effect on
receiving
electron
behavior
Increase
the
frequency
decrease
increase
increase
faster
faster
Increase
the
amplitude
increase
decrease
increase
faster
faster
Conclusions
I noticed from my results that wavelength is inversely proportional to the number of waves between the antennas. We can also see that the frequency and amplitude both influence the speed of the electrons in the simulation. We saw on our results that as we
increased the frequency, the transmitting and receiving electron also increased in speed, as well as when we increase the amplitude, we also saw an increase in the transmitting and receiving speed. Summary and Reflection
Summarize the major findings of this exploration. What do you know now that you did not know before? Be specific.
Static electric fields have lines pointing towards the electron, while radiated fields have lines pointing away from the moving electron. Something I did not know but now do is that the direction of the electric field and the force acting on the electron are always opposite. Electrons in a receiving antenna
move in response to the electromagnetic waves from a transmitting antenna. They mimic the motion of the transmitting electrons, but slower and with a smaller range. The curved path of the receiving electron suggests a repulsive force, aligning with the principle of like charges repelling. The wavelength of the electromagnetic was is inversely proportional to the number of waves observed between the antennas. Lastly a major finding of this exploration is that increasing the frequency or amplitude of the wave, increases the speed of both transmitting and receiving electrons.
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