2.Methods

Independent variable


The frequency being imputed into the speakers

165Hz


330Hz


495Hz


660Hz


825Hz


990Hz





2.1 Equipment List


2x Speaker which frequency can be adjusted
1x Transparent Cylindrical tube(acrylic)
1x Pitch generator
1x Amplifier
1x  2 meter of wires
1x decibel meter 
2x holder to keep tube from moving


2.2 Diagrams of experimental setup 

 

Figure 1: Experimental setup used to find the frequencies where there is a new harmonic





Figure 2: Actual Set-up





Figure 3: frequencies to expect a harmonic calculated by the formula( frequency=v/2l)


2.3 Procedures

1. Set up the experiment as shown in the diagram above. make sure the wiring is correct


2. Adjust the frequency on the pitch generator to an audible frequency(20-20000 hz) to test if the speaker is working, if a sound is heard, move on to next step.
     If sound is not heard, check and/or change wiring and try again

3. Adjust the pitch generator starting from to the frequencies in figure 2 and tune the frequency around


4.Check the decibel meter. when the db shown suddenly becomes high, note down the frequency shown on the tone generator



5. repeat step 3 for each value shown in figure 2

6. repeat step 3 to 5 at least 3 times, average each test’s results, then transfer the information to the chart



2.4 Risk Assessment and Management  



Risk
Assessment
Management
The experiment would involve electricity,there is a risk of electrocution if a student comes into contact with exposed wiring



Medium
Students must wear gloves made of non conductive materials when carrying out the experiment and all exposed wires must be wrapped around with insulating tape whenever possible.these measures are to prevent electricity from being passed to a student.
the end of wires involved in the experiment might be sharp, and if we are not careful, we might be barbed.



Low
students must wear gloves mentioned in the previous risk, and unused wire’s ends must be tied in a knot in order to cover the sharp part
setting up of the experiment will involve soldering , hot metals will be produced , if in contact with bare skin, burns may occur



Medium
warn researchers about risk and make sure we do not  touch soldered parts for 5 min after soldering. make sure researches know of procedures of treatment in case of burns
As the experiments involve sound, and loud sound might damage eardrums of those around. The risk of hearing damage is present



Low
make sure that experimentation does not go beyond 100 db or point , wear noise isolating ear plugs if possible and ensure that people that are not part of the experiment experiment not come too close to an ongoing experiment(3 meters)
Table 1: Risk Assessment and Management table


Harmonics/Resonance
Frequency of the nth harmonics (Db)                             

test 1
test 2
test 3
Average
1st




2nd




3rd




4th




5th




6th





Table 2: sample of results table




Figure 4: Sample Graph of frequency (Hz) against intensity (dB)



2.5 Data Analysis


1.    Tabulate the data and calculate the average frequencies when resonance occurs


2.    Plot a graph of the frequency and the frequency where a new standing wave appears

3.    From the graph, we can find out how frequency affects the amount of standing waves produced

4.  From the graph, we can find out at what frequencies new standing waves form

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