Bret+and+Scott+Lab

Lab: Frequency, Harmonic Number, and Wavelength
Date: 5/24/11 Group: Bret Pontillo and Scott Siegel Class: Honors Physics Period 4

Objective: What is the relationship between frequency and the tension of transverse waves traveling in a stretched string? What is the relationship between frequency and harmonic number? What is the relationship between frequency and wavelength?

Hypothesis: - There will be a linear, direct relationship between the frequency and harmonic number. - There will be a direct relationship between the frequency and tension of the string. There will be this direct root relationship because increasing tension increases velocity, if velocity increases and our constant is wavelength, frequency will increase. - there will be an inverse relationship between the frequency and wavelength of the string. This is from v= frequency x wavelength, as frequency increases, wavelength will decrease.

Materials: 1. Electrically-Driven Oscillator 2. Pulley 3. Clamp (for the table, holding down the oscillator) 4. Weight Holder 5. Various Masses 6. String 7. Electronic Balance 8. Meter Stick

Procedure: 1. Gather the necessary materials. 2. Set up an Excel Spreadsheet. 3. Clamp the oscillator to one end of the tabletop. 4. Tie a piece of string to the oscillator and attach the other end of the string to a pulley, clamped at to the opposite end of the tabletop. 5. Select various frequencies and amplitudes using the electronic dial on the oscillator. 6. Measure each wavelength of the various frequencies and amplitudes. 7. Record the number of nodes and anti-nodes for each combination. 8. Add various masses to the end of the string to confirm that the string is parallel to the table, giving us the most accurate results. 9. Run 5 trials for each combination of frequency and amplitude using the previous steps. Data: Graphs:



Calculations:

Percent Difference for Antinodes vs. Frequency Discussion Questions: 1. Calculate the tension T that would be required to produce the n = 1 standing wave for the red braided string. 2. What would be the effect if the string stretched significantly as the tension increased? How would that have affected the data? A: This would increase the wave speed, which affects the wavelength and frequency. The wavelength of the wave would decrease, while the frequency would increase. 3. What is the effect of the type of string on the amount of hanging mass needed to create a set number of nodes? Explain this. A: The type of string is directly affects the tension and elastic property of the string. The stronger the string, the more mass is necessary to result in the same tension as a weaker string would have. 4. What is the effect of changing frequency on the number of nodes? A: Changing the frequency affects the interference of the waves. Changing the frequency can result is a resonance; however, it will occur at different points than the previous resonance. Nodes are where the crest of one wave meets the trough of the other wave, resulting in an amplitude of zero. 5. What factors affect the number of nodes in a standing wave? A: The length of the string and the wavelength affect the the number of nodes in a standing wave. Being that it changes the pattern of interference of the two waves, the frequency also affects the number of nodes in a standing wave.

Conclusion: