PHY112 Lab 9
Name __Isaiah Mata________
Radio Waves
Section _19543___
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
With the electron static at the top of the antenna, the electron
is surrounded by small vectors facing towards the electron.
Static field, move electron
down the antenna
With the electron moving down the pole, there are vectors
that follow the path of the electron and then fade away. As the
electron goes down, another pair of vectors follows the
electron.
Radiated field, motionless
electron
With the electron not moving there is no change in the field.
Radiated field, move
electron down the antenna
With the electron moving down the antenna, there are a group
of vectors that surround the antenna and move in a wave
away from the electron.
Radiated field, oscillating
electron
With the vector oscillating, vectors form around the electron in
waves that switch direction each oscillation cycle.
Conclusions
The radiated field best simulates the action of electromagnetic
waves. This is most accurate when the particle is oscillating ata
constant rate.
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 force on electron and electric field are opposite in terms of the
direction of vectors. They are the same at the equilibrium point of the
antenna.
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?
The electrons do not start moving at the
same time. The transmitter moves first. The
receiver only starts moving only when it
receives the waves from the transmitter.
When the transmitting electron is at its
maximum position, where is the receiving
antenna electron (e.g., max, min, zero, or some
other position)?
The receiving antenna is also at max position.
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 completes a full
cycle slightly faster than the receiving
electron.
Compare the distance the transmitting electron
travels in one full cycle to the distance traveled
by the receiving electron during one full cycle.
The transmitting electron travels a further
distance than the receiving electron does.
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.
The motion of the receiving electron is slightly behind the transmitting electron to compensate for
the travel time of the waves between the two. The vector wave changes the direction of the
electron. The motion is a direct result of the vector wave created by the broadcasting antenna.
When the wave is pointing down leaving the antenna, it causes the other electron to move in that
direction when it hits it. This relates to my observation in table 3 about how there is a delay in the
movement of the receiving electron. The receiving electron doesn’t move first because it depends
on the transmitting antenna’s movement. In table 2 I also recognized that the force on the electron
is opposite the direction of the max and min of the electron. For example, when the electron is at
max height the force acts down to force the electron back towards equilibrium.
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 screenshot. Paste the screenshot into the space below. NOTE: Beginning Fall
2024: All required photos / screenshots must be included in order for your lab report to be
graded. Lab reports with no photos / screenshots will receive no credit.
Answer the following observation questions based on the above picture.
Observation question
Answer
Roughly, how many electric
waves are present in the above
picture?
There are three clusters of electric waves.
How could you use this electric
field diagram to determine the
length of the electric waves?
We could identify the peaks of the waves and measure
the distance between them.
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 curved line represents the oscillating wave from the transmitting antenna to the receiving.
This is because it mimics the behavior of waves created from the transmitting antenna to the
receiving.
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
Effect on wave
amplitude
Effect on
transmitting
electron
behavior
Effect on
receiving
electron
behavior
between the
antennas
Increase
the
frequency
Decreases
Increases
Increase
the
amplitude
I did not
notice a
significant
difference
Did not
change
Increases
Speeds up its
motion
Speeds up its
motion
Increases
Increases the
distance it
travels
Increases the
distance it
travels
I concluded that changing both frequency and amplitude does not change the
relationship between the transmitting electron and receiving electron’s behavior. I also
Conclusions concluded that amplitude has the largest affect on the distance the electrons travel.
This in turn affects the height of each wave sent.
Summary and Reflection
Summarize the major findings of this exploration. What do you know now that you did not know
before? Be specific.
Through this experiment I learned that the receiving antenna is entirely dependent on the
transmitting antenna. I also learned that each wave is associated with a force that acts on the
receiving electron. This force is opposite the direction of the max or min of the receiving electron so
that it travels in an oscillating pattern. I learned that the force on the electron points in the opposite
direction of the electric field.