Download AAPT Poster - Rensselaer Polytechnic Institute

Application of the Rensselaer Mobile
Studio I/O Board in an Introductory
University Physics Course*
Peter D. Persans1, Stephanie Tomasulo1,
Gwo-Ching Wang1,
and Don L. Millard2
1Physics,
Applied Physics, and Astronomy
2Electrical, Computer & Systems Engineering
Rensselaer Polytechnic Institute, Troy NY
(*work supported by the NSF)
[email protected]
http://ioboard.rpi.edu
Physics in the Rensselaer Studio Model

Two two-hour studio
classes per week
Reading quiz
Homework review
Short lectures on
new material
Quick feedback questions
Experimental/conceptual activity

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48 students in 16 groups of 3
One professor, two TA’s
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Some Issues with the Studio Model
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Studio pedagogy uses dedicated spaces and
laboratory instrumentation
One experimental set-up for three students
Studio facilities need staff and maintenance
Studio activities must be accomplished
quickly and efficiently
Students don’t get sufficient exploratory time in
the studio mode.
Timing and equipment expense constrains
activities
One student frequently dominates activity
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Physics II at Rensselaer

Electric fields, forces, potential
Gauss’ Law, Capacitors, DC circuits

Magnetic fields and forces
Fields from currents

Faraday’s Law and inductance
AC circuits

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Maxwell’s equations and electromagnetic
waves
Waves and oscillations
Wave interference, diffraction

Concepts in quantum physics
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A typical experimental activity
Wave Interference - Beats
In this activity, students create audible signals using
two audio function generator programs on their
laptops. The audio signal is picked up with a
microphone and observed on an oscilloscope.
When the frequencies differ, a beat signal is
observed.
Equipment:
PC function generator (2)
2 channel oscilloscope
Audio pick-up microphone
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So what if … ?
We could enable students to perform
sophisticated, quantitative
experiments anyplace at anytime…
Dormitory room
Student Union
Library
Campus meeting rooms
Etc.
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The Mobile Studio
RED2 I/O Board Specifications
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Operates through USB port of PC
2 A/D inputs, configured as a
dual channel scope (~1.45MS/s)
2 D/A (FG/AWG) outputs
2 PWM output ports
16 Digital outputs/inputs (software configurable)
+/- 4v, 3.3v, 5v Power supplies (capable of
delivering ~ 100mA)
A wireless transceiver for remote sensing &
control
~ $150
An audio amplifier
(stereo headphone jack on the board)
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Mobile I/OBoard Activity Development

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
Fall 2007 – develop I/OBoard versions of
studio activities that use oscilloscope and
function generator (7 out of 20 activities)
Spring 2008 – try out activities in our Honors
Physics II course labs
Fall 2008 – IOBoard based activities were
run for one Studio section (out of twelve
parallel sections)
Most students purchased/borrowed an IOBoard
with electronics kit
Each student had to perform most activities
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Mobile I/OBoard Activities - F2008

Setting up/using the oscilloscope*
AC voltage divider (C1-C2)
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RC and RL decay*
AC reactance (RL, RC)*
Diode IV curve
LC ringing
RLC resonance
Audio frequencies and hearing*
Audio beats
* take-home activity component
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The Mobile Studio Audio Beats Activity*

Dual function generator on IOBoard is used to
generate periodic signals
Function generator output drives headphones or amplified
speakers directly.
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Dual oscilloscope plus math functions are used to
observe output to speakers plus sum signal.
Audio or function generator output can drive filter
circuit.
Filter output can be viewed on oscilloscope screen and heard.
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Students can explore sound and circuit behavior
outside of class.
Students can store waveforms in csv format for
later analysis
*see handouts
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The Mobile Studio User Interface
Evaluation overview
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Students in regular studio and mobile
studio class had same lectures, similar
activities, took same exams.
Class to class comparison was performed
on all test items and overall.
Student input gathered via online IDEA
forms.
Student input gathered via in-class
surveys.
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Example test item
10
8
6
Emf(V)
4
2
0
-2 0
100
200
300
400
500
-4
-6
-8
-10
time (microseconds)
_____A1) The root mean square (rms) value of the emf in Fig. A1-4 is
closest to:
A) 10V
B) 20 V
C) 14 V D) 7V
E) 0V
_____A2) The frequency in Hz of the oscillating emf in Fig. A1-4 is
closest to:
A) 500 Hz
B) 5000 Hz C) 3070 Hz D) 200 Hz E) 2x10-4 Hz
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Example test item C-1
The RC circuit shown below is
driven with a harmonic emf of
.
v(t )  10V cos  2 ft 
The value of the resistance is
1000 ohms.
a) Write an equation for the
reactance of the capacitor as
a function of frequency f.
b) At a driving frequency f=10,000
Hz, the amplitude of the
voltage across the resistor is
the same as that across the
capacitor. What is the value
of the reactance of the
capacitor at this frequency?
C
R
c) What is the value of the
capacitance?
d) What is the amplitude of
the voltage across the
capacitor at 10,000 Hz?
Explain your answer.
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Mobile Studio results

Performance on classwide tests was compared.
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
B1
B2
B3
B4
C1
average MSG
3.47
4.00
3.73
3.73
2.13
0.80
2.67
1.33
3.73
3.20
4.80
7.40
7.20
6.27
9.73
13.00
77.20
Average,
control
2.86
3.81
2.76
2.67
3.05
1.90
2.10
1.33
3.62
3.05
4.05
7.86
7.48
6.71
7.88
12.93
74.05
1.30
1.43
2.43
2.64
-1.49
-2.04
0.94
0.00
0.34
0.30
1.57
-1.06
-0.65
-0.55
0.10
0.86
diff 4-5
/stdev (4-5)
C2
1.79
Green – Mobile studio group >1 deviation above control group.
Red – Control group > Mobile studio group.
Problems A1-A4 and C1 involved interpretation of oscilloscope graphs and ac circuits.
Mobile Card class consistently overperformed on oscilloscope and ac circuits problems.
Their performance on other material was randomly above and below average.
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Why the difference?
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Each student in Mobile Studio class
performed the activity himself/herself.
Digital data storage permitted later analysis
and plotting.
Use of IOBoard outside of class
Assignments
Students played with the audio functions

Students interface differently with GUI than
with knobs
With Mobile interface they have to choose the
scales rather than twiddle knobs.
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Future work

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Expand activities to include use of boards
outside of class
Design activities to take advantage of special
IOBoard features
audio amplifier output
digital data storage
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Expand implementation to hundreds of
students
Add wireless daughter card with
accelerometer, force gauge, position sensor
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Contact Information

Peter D Persans
Department of Physics, Applied Physics, and Astronomy
Rensselaer Polytechnic Institute
110 8th Street, Troy NY 12180
[email protected] www.rpi.edu/~persap

For I/O Board information:
[email protected]
http://ioboard.rpi.edu
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