This is my Laboratory Blog. It consists of the different Engineering Physics Labs that I have done in class over the duration of the Spring 2013 Semester at Mt. San Antonio College :)
Purpose: To explore the images formed by convex and concave
mirrors through direct observations and light ray
diagrams
Equipment:
Convex mirror
Concave mirror
Worksheets at the end of lab activity packet
Ruler
Object(myself)
Experiment:
Part A
- Convex Mirror
Far Away from Convex Mirror
From the direct observations, a convex mirror will make an object appear smaller
than the same size object from a far distance. This object remains upright.
Clore up to Convex Mirror
As the object is brought close up to the convex mirror, the image appears larger
than the same size real object.
From a farther distance than the
first picture, the image appears to be so far it disappears.
Part B -
Concave Mirrors
Close up to Concave Mirror
As the object(me) got closer to the mirror, the image became bigger and remained upright.
Close up to Concave Mirror
As the object was much further away, the mirror image was much smaller and inverted, as depicted in the picture above.
Conclusion:
Based on the light ray sketches, bellow of a convex and concave mirror respectively, we can conclude that the observations and calculations match based on the magnification value.
Purpose: To use the geometry of a semicircle to analyze the properties of reflection and refraction when an electromagnetic wave travels through a medium of a different material.
Equipment:
Light box
Semicircular plastic
Circular protractor
Experiment:
A beam of light was emited from a light box position at a known angle onto the circular protractor.
The refracted wave will have a different angle than the angle of incidence, normal to the surface of the semicircular plastic.
Through visual analysis, a difference can be recorded using the opposite side of the circular protractor. Increasing increments of 5-8 degrees will be used for a total of 10 trials.
Prism A - Incidence Ray onto circular side
Data Collected for Set up Demostratrated Above - Part A
Prism B - Incidence Ray onto flat side
Data Collected for Set up Demostrated Above - Part B
Conclusion:
Part A)
The light ray on the onto the curved surface of the semicircular prism was reflected as predicted. The Linear regression line and slope of sinӨ1 vs sinӨ2 represent the n(air)/n(glass).
This makes sense since the index of refraction of the prism is greater than air(1.00), therefore the slope being less than 1 confirms the relationship of the difraction in the prism.
Part B)
Re-enforceably, the results were once again attained from the reversed physical set up of the prism. The slope from the linear regression line was the same, comfirming the same index of refraction of the prism.
Purpose: To use a simple antenna made from a short piece of metal to analyze the behavior of electromagnetic radiation.
Equipment:
Copper Wire
Two Meter Sticks
BNC Connector
Frequency Generator
Oscilloscope
Experiment:
Transmitter to the high frequency oscillator, with free space between the two antennae
A transmitter was created by attaching the copper wire to a meter stick with tape. Then, one end to the frequency generator was connected, this create a
receiver by having a pluggin at the BNC connector into the oscilloscope.
BNC connected
The frequency generator was used to create a frequency of 30 kHZ with the amplitude to its maximum.
Frequency generator set at 30kHz
Change the time/div setting on the
oscilloscope to 0.1 ms and decrease the voltage/div until a signal in
seen on the screen.
Oscillator set at 30kM with a max amplitude, with the oscilloscope at 0.1ms
The measurements of the peak to peak amplitude of
the EM wave were observed for several trials.
Conclusion:
The data does not fit the A/r function as it was expected if it were a
point charge due to the fact that the transmitter is linear perpendicular to the
receiver. Therefore, the entirely of the copper wire length must be taken at each dx and consider that instead of a
single point source.
The A/x
function has a better fit for the data compared to the A/r^2. Yet, the fit is still not a complete fit.
The additional A/r^n function actually fits the best.
Purpose: To use student voice produced and harmonic turning-fork sound waves to conceptualize the wave like properties of sound.
Equipment:
LabPro
Microphone
Singers(Students)
Experiment:
The experiment collected a 0.03 second recording of an "AAAAAAAA" from a students, a much more harmonic turning fork striking a soft surface.
The following questions were proposed and asked to be answered for all Parts A thru D
1)Would you say this is a
periodic wave?Support your answer with
characteristics.
2)How many waves are shown in this sample?Explain how you determined this
number.
3)Relate how long the probe collected data to
something in your everyday experience. For example: “Lunch passes by at a snails
pace.” Or “Physics class flies by as fast as a jet by the
window.”
4)What is the period of
these waves?Explain how you determined
the period.
5)What is the frequency of these waves?Explain how you determined the
frequency.
6)Calculate the wavelength assuming the speed of
sound to be 340 m/s. Relate the length of the sound wave to something in the
class room.
7)What is the amplitude of
these waves?Explain how you determined
amplitude.
8)What would be different about the graph if the
sample were 10 times as long? How would your answers for the questions a-g
change? Explain your thinking. Change the sample rate and test your ideas. Copy
the graph and label it #1h.
Part B Specific:
Have someone else speak
into the microphone and compare and contrast the two graphs.
Part C Specific:
Then use a
tuning fork to produce a graph and compare and contrast that graph against the
human graphs.
Part D Specific:
What would you expect if the tuning fork wasn't as loud
as the first time?
Conclusion: Part A:
"My beutiful Voice" by Jose Comi
1)This wave is periodic since it repeats similar
to a sinusoidal wave.
2)5.4 waves are in this sample.
3)The data was collected over 0.03 seconds which
is faster than you blink.
4)The period of the wave is 0.0056 seconds.We determined this by dividing the sample
time (0.03) by the number of waves (5.4).
5)The frequency is 180 Hz.We determined this by 1/T and confirmed it by
extrapolating 5.4 waves in .03 seconds and looked at how many waves in one
second (frequency).
6)The wavelength equals velocity divided by the
frequency.(340m/s) / (180 s-1)
= 1.89m.This is about the length of a desk.
7)The amplitude is 1.8 units.We determined this from the graph.
8)Everything would be the same except you would
have more waves in the sample.
Part B:
"The sound of aerospace" - Jason Shaw
1)The second wave sampling was not as regular as
the first.There are 3.5 waves in the
sample which is 0.03 seconds.The period
is 0.0086 seconds.The frequency of the
wave is 116 Hz.The wavelength is 2.93
m.The amplitude is 0.75 units.
Part C:
The tuning fork produces a much more uniform sound wave
compared to the human waves.There are
15 waves in the sample of 0.03 seconds.The period is 0.0020 seconds.The
frequency of the wave is 500 Hz.The
wavelength is 0.68 m.The amplitude is
0.23 units.
Part D:
Only the amplitude of the wave changed (decreased) while the
other data remained the same.We changed
the impact surface to a softer material (skin/pants vs rubber shoe sole) which
resulted in a softer wave.
Purpose: To understand the characteristics of standing waves in resonance driven by an external force(oscillator)
Equipment:
2.00 meters of string
Mechanical Vibrator
Function Generator
Pulley
Table Clamps
50 g and 200 g Counterweight
Two-Meter Stick
Experiment:
Video of the laboratory procedure and set up
(pics of harmonic string waves hard to capture)
A 200g counterweight was positioned at the end of 2.00 meters worth of string onto a pulley. This was then string as extended across the able to a ring stand on its opposite end.
0.00083
Mass of String (g)
2.495
Length of String (m)
0.0003327
Linear Density (kg/m)
1.800
Effective String Length (m)
The function generator to the mechanical vibrator was placed on the the string, propagating a sinusoidal wave.
The generator was adjusted until the string
oscillated in its fundamental mode.
The number of nodes, length between nodes, wavelength, frequency and voltage were recorded, and repeat
for eight antinodes.
Part A - 200g Counterweight
# of Antinode
Length Node to Node (m)
Frequency (Hz)
λ (m)
1/λ
Theoretical Speed
1
1.800
24
3.600
0.2778
86.40
2
0.910
44
1.800
0.5556
79.20
3
0.595
66
1.200
0.8333
79.20
4
0.450
88
0.900
1.1111
79.20
5
0.370
110
0.720
1.3889
79.20
6
0.310
131
0.600
1.6667
78.60
7
0.265
154
0.514
1.9444
79.20
8
0.225
177
0.450
2.2222
79.65
Average Speed
80.08
Part B - repeated procedure for 50g Counterweight
# of Antinode
Length Node to Node (m)
Frequency (Hz)
λ (m)
1/λ
Theoretical Speed
1
1.800
11
3.600
0.2778
39.60
2
0.900
22
1.800
0.5556
39.60
3
0.620
33
1.200
0.8333
39.60
4
0.470
44
0.900
1.1111
39.60
5
0.350
55
0.720
1.3889
39.60
6
0.315
66
0.600
1.6667
39.60
7
0.265
77
0.514
1.9444
39.60
8
0.225
88
0.450
2.2222
39.60
Average Speed
39.60
Conclusion:
Experimental Values
Theoretical Values
78.771
Case 1 Speed (m/s)
80.08
Case 1 Speed (m/s)
39.600
Case 2 Speed (m/s)
39.600
Case 2 Speed (m/s)
1.989
Ratio Case 1 / Case 2
2.022
Ratio Case 1 / Case 2
The experimental values and theoretical values were at a 1.6% error. This is furthered re-enforced by the graphs of frequency vs 1/λ
