# Monday, 30th June 2014

Continued to do the experimental with Doppler Effect using a pizzo buzzer as a source and a simple mic as a detector. Facing difficulties is calculating apparent frequency in case of oscillating source.

It is easy to calculate Doppler frequency shift in case of a source moving with constant velocity. Both the experimental setups are ready. Created a draft document for experimental procedures. Need to review and finalize the document. Also worked on the required python code to fetch data from detector and get the Doppler Shift.

# GSoC Weekly Report 6

The previous week ( From Monday 23rd to Sunday, 29th June 2014) we could setup some new experiments to study the phenomena of Friction and sound.

Submitted the midterm evaluation on June 25th. On 28th midnight at 12.45 am…..got the happiest news that I have successfully passed the Google Summer of Code 2014 – Midterm Evaluation….. awesome moment I was waiting for….. Thanks a million to my mentors for all the guidance, help and encouragement.

Also received message from Payoneer that they have processed my GSoC payment. Now I can order some equipments Like Audio Frequency Oscilloscope and amplifiers for my Project. These equipments will help me to try the experiments and achieve the same with ExpEYES later.

Things We Could Do….

• Setup an experiment to obtain Lissajous Figures using Square waves with various values of phase difference. Repeated the experiment with sine waves. Phase difference can be added with a capacitor and resistor circuit.
• Started working on an experimental setup to produce these pattern in 3 Dimensions using Laser and Speakers.
• Submitted the midterm evaluation report.
• Completed the  set-up of a mechanics experiment to study conservation of momentum.  Wrote  python code to get the data.
• Designed an instrument using  a  pulley and a photo-gate to measure acceleration. ( thanks to open educational resources for the idea..)This can be used  for different experiments involving friction.
• In an experiment  to study oscillations of a loaded spring, we could obtain position time data and plot graph.To determine the spring constant of the given spiral spring we need to measure frequency and time periodic time.I could get this done by fitting the data by using a python code.
• Set-up for demonstration of Doppler effect is ready. I used A buzzer attached to a spiral spring and made it oscillate in-front of the mic.
• Prepared the experimental set-up For Doppler Effect. I have used the linear air track and fixed the source of sound on the glider. the emitted sound waves can be detected by a microphone fixed in ExpEYES. We can determine the original frequency of the source using ExpEYES and then the source is set in to motion and again frequency is determined.  A photo-gate is used to measure the speed of the source.
Things To Do Next Week….
• GUI for experiments with Friction
• GUI for Doppler Effect
• Documentation for all these Experiments
• Python Code for a separate GUI for Plotting data from all channels of ExpEYES.

# Sunday, 29th June 2014

Since yesterday I am working on setting up of an experiment to study Doppler effect in sound.

If the source of sound or the detector is in motion relative to the medium of propagation, the frequency of the waves that are emitted  appears to be changed due to Doppler Effect. This is an interesting experiment at Higher Secondary level.

The experimental set-up is ready. I have used the linear air track and fixed the source of sound on the glider. the emitted sound waves can be detected by a microphone fixed in ExpEYES. We can determine the original frequency of the source using ExpEYES and then the source is set in to motion and again frequency is determined.  A photo-gate is used to measure the speed of the source.

The apparent frequency is related to the speed and the original frequency. The experimental results can be verified by theoretical calculations.

Practical Application:

1. General Study of Doppler Effect
2. For different frequencies, measure the Doppler shift with different velocities of the sound emitter. Compare the theoretical and experimental results.

The python code required for measuring frequency and also to determine speed using photo-gate  is already written. I could get good results in my experimental trials.

Tomorrow I will work on developing a separate code for a simple GUI for this experiment.

# Saturday, 28th June 2014

Today I started working on an interesting experiment in sound and Waves. It is very  difficult to do experiments involving Doppler Effect in conventional laboratory. But with the help of ExpEYES Doppler Effect can be Demonstrated very easily.

The experimental set-up for demonstration of Doppler effect is ready. We need a moving source relative to the detector. Detector is the simple mic inside ExpEYES. For getting  a source which is harmonically oscillating, I used A buzzer attached to a spiral spring and made it oscillate in-front of the mic.

First, the frequency of the emitted signal is measured at rest. Then, the frequency shift that is caused by the oscillating source is measured. this can easily demonstrate ‘the apparent change in the frequency due to Doppler Effect.

My next step is to develop a set-up to measure Doppler Shift in case of a moving source with constant velocity. For this I am planning to use my linear air track which is developed for mechanics experiments, so that the cost can be reduced.

# Thursday, 26th June 2014

In an experiment  to study oscillations of a loaded spring, we could obtain position time data and plot graph.

To determine the spring constant of the given spiral spring we need to measure frequency and time periodic time.

Today I could get this done by fitting the data by writing the following code…

from pylab import *
import expeyes.eyesj, time
import expeyes.eyemath as em

p = expeyes.eyesj.open()
p.set_state(10,1)
f = open(‘srf.dat’,’r+’)
ta = []
da = []
strt = time.time()
et =0
while et < 30:
dist = p.srfechotime(8,3)
et = time.time() – strt
ta.append(et)
da.append(dist)
s = ‘%5.3f\t %d’%(et,dist)
#s = ‘%d\t %d’%(et,dist)
f.write(s + ‘\n’)
print s
time.sleep(0.1)
vfit, par = em.fit_sine(ta,da)
print par
plot(ta, vfit)
plot(ta,da)
#plot(t,v)
show()

par[1] gives frequency of oscillations..

Now I will create the  GUI and the experiment will be completely ready…. 🙂

# Tuesday, 24th June 2014

Today I could complete set-up of a mechanics experiment to study conservation of momentum. In this experiment we can determine momentum of both gliders on air track, before and after collision. Different types of collisions can also be studied.  Wrote  python code to get the data. Need to debug the errors and develop a GUI, where user can enter the values of masses of both the vehicles and get the value of momentum, which is the product of mass and velocity.

Today we could also design an instrument using  a  pulley and a photo-gate to measure acceleration. ( thanks to open educational resources for the idea..)

Tomorrow I will work on setting up of this new instrument for different experiments involving friction.

# Monday, 23rd June 2014

Explored possibilities of obtaining Lissajous Figures using Square waves with various values of phase difference. Repeated the experiment with sine waves. Phase difference can be added with a capacitor and resistor circuit.

Started working on an experimental setup to produce these pattern in 3 Dimensions using Laser and Speakers. For this I need an amplifier to drive two speakers. Sine waves and the required phase difference can be obtained from ExpEYES with python code. I could get beautiful  Lissajous figures using manual method . Used two speakers with amplifiers and laser. Sine waves are obtained from AFO.

Need to do this with ExpEYES. It will be a very compact and most affordable set-up to produce Laser Lissajous Figures in 3D.

these concepts have been included in First Year B.Sc. Course of most of Indian universities. Students study these things only in theory and the never get to see the real Lissajous figures. . Our project has a potential to change this effectively. Hope it will be ready soon…..

Tonight, Evaluation Links will be enabled on Google-melange site. Need to prepare and submit the mid-term evaluation.

# GSoC Weekly Report 5

The past week ( From Monday 16th to Sunday, 22nd June 2014) was really productive in terms of experimental setups and trials with python codes. My mentors offered all the help and guidance and were very  encouraging and helped me to speedup the things….

What We Could Do….

• Started creating documents for experimental setups and procedures for mechanics experiments and a few sound experiments.
• Made necessary changes in python programs for using SRF 05 sensor. Did the experiments on linear air track to obtain position -time plots.
• Ordered and received additional Ultrasonic sensors SRF 05. Did the testing work for all ten pieces of srf modules. They all are working good.
• Wrote three programs for time measurement using photo-gates and explored the use of time measurement functions like r2rtime r2f time and multir2rtime and updated changes to Git repo.
• On Wednesday, started giving finishing touch to the following experiments…. Frequency of Oscillations of Spiral Spring, Parallel and series combination helical springs and the resulting spring constant, Uniformly accelerated motion on an inclined plane, Conservation of momentum.
• On Thursday, Continued working on giving finishing touch to the experiments..Had to spend a lot of time with photo-gates. The problem in accessing Light sensors (Photogates) is partially solved……… Now I am able to make time measurements using these light sensors.
• Completed the setup and documentation for Spring oscillations experiments. Here are the screen shots of the experiment with spring oscillations..
• One more positive development that has happened is…now we are able to access ExpEYES with android phone or tablets….Thanks to Jitin B.P. for this application.I could connect ExpEYES to my Micromax Canvas 4 Phone…the screen shots shows sine waves and square waves connected to different channels…. Now, our dream of providing an open source science pocket lab to every student has come closer to the reality.
• Wrote and commited some simple python programs required for time measurements and plots to git repo.
• On Saturday, worked on an experiment to produce Lissajous figures using two square waves. Wrote Program in python and tested the same. Could obtain various Lissajous patterns.In the code we used Capture2 function from ExpEYES library to plot the figures. used two sine waves with a phase difference of 90 degrees.
• On Sunday, continued to work on experiments to produce Lissajous Figures. Generated two square waves with a phase co relation between  them. Used Capture2 function to capture data and plot graphs. The figures are sensitive to phase difference and the ratio of frequencies.These are the patterns obtained……smooth curves can be obtained using sine waves…
Difficulties Faced…
• I was facing some difficulties in some experiments while using two photo-gates simultaneously for time measurements. The problem is partially solved. Need to fine a good and permanent solution. Ability to use two photo-sensors simultaneously can make many mechanics experiments easy.
• For spring Oscillations experiment…difficulty in Fitting the curve to get frequency.
• The smooth Lissajous Figures are expected if we use two sine waves instead of square waves. Working on the module to generate two sine  waves of variable frequency.

To Do………

• Work on accessing Photo-sensors. Write necessary python code.
• Write a code for fitting different curves.
• Create a GUI where user can change the phase between the two waves and can obtain different Lissajous patterns.
• My Next Step would be to produce these pattern in 3 Dimensions using Laser and Speakers. For this I need an amplifier to drive two speakers. Sine waves and the required phase difference can be obtained from ExpEYES with python code. Aiming at beautiful Laser Show with a lot of science in it…. 🙂
• Documentation with experimental procedure for the experiments developed.
• Taking Photos/Videos of set up and also upload screen shots.

Here is my git activity for this week   https://github.com/wavicles/Plugins-for-ExpEYES/commits/master

# Sunday, 22nd June 2014

Continued to work on experiments to produce Lissajous Figures. Generated two square waves with a phase co relation between  them. Used Capture2 function to capture data and plot graphs. The figures are sensitive to phase difference and the ratio of frequencies.

This is the code used.

from pylab import *
import expeyes.eyesj
p = expeyes.eyesj.open()

#p.set_sqr1(8000)
#p.set_sqr2(4000)
p.set_sqrs(8000,13)

t1,v1,t2,v2 = p.capture2(1, 2, 400, 16)
figure(3)
plot(v1,v2)
show()

These are the patterns obtained…

The smooth Lissajous Figures are expected if we use two sine waves instead of square waves. Working on the module to generate two sine  waves of variable frequency.

Thats all for today…….:)

# Saturday, 21st June 2014

Today worked on an experiment to produce Lissajous figures using two square waves. Wrote Program in python and tested the same. Could obtain various Lissajous patterns.

In the code we used Capture2 function from ExpEYES library to plot the figures. Here is the example…

_________________________________________________________________________

from pylab import *
import expeyes.eyesj
p = expeyes.eyesj.open()
from pylab import *
t1,v1,t2,v2 = p.capture2(1, 2, 300, 100)
figure(1)
plot(t1,v1)
figure(2)
plot(t1,v1, t2,v2)
figure(3)
plot(v1,v2)
show()

__________________________________________________________________________

figure 1 is a sine wave connected to channel A1

figure2 shows the phase different introduced using a 1 microfarad capacitor and 1kilo ohm resistor.

this is the resulting Lissajous pattern…..

Need to create a GUI where user can change the phase between the two waves and can obtain different patterns.

Tomorrow I will be working on the same experiment to produce different patterns.

### Following is the related information

Source :

1. http://www.britannica.com/EBchecked/topic/343305/Lissajous-figure
2. http://en.wikipedia.org/wiki/Lissajous_curve

Lissajous figure, also called Bowditch Curve, pattern produced by the intersection of two sinusoidal curves the axes of which are at right angles to each other.

If the frequency and phase angle of the two curves are identical, the resultant is a straight line lying at 45° (and 225°) to the coordinate axes. If one of the curves is 180° out of phase with respect to the other, another straight line is produced lying 90° away from the line produced where the curves are in phase (i.e., at 135° and 315°).

Otherwise, with identical amplitude and frequency but a varying phase relation, ellipses are formed with varying angular positions, except that a phase difference of 90° (or 270°) produces a circle around the origin. If the curves are out of phase and differing in frequency, intricate meshing figures are formed.

The appearance of the figure is highly sensitive to the ratio a/b. For a ratio of 1, the figure is an ellipse, with special cases including circles (A = B, δ = π/2 radians) and lines (δ = 0). Another simple Lissajous figure is the parabola (a/b = 2, δ = π/4). Other ratios produce more complicated curves, which are closed only if a/b is rational. The visual form of these curves is often suggestive of a three-dimensional knot, and indeed many kinds of knots, including those known as Lissajous knots, project to the plane as Lissajous figures. (REF: http://en.wikipedia.org/wiki/Lissajous_curve)

• a = 1, b = 2 (1:2)
• a = 3, b = 2 (3:2)
• a = 3, b = 4 (3:4)
• a = 5, b = 4 (5:4)