Question

PHET Sound Simulation Purpose - To explore sound (a longitudinal wave) and how it can be modeled as a transverse wave Obtain com puter with PHET software on it. Get headphones if possible and plug into sound port. Open PHET simulations and find Sound and Waves simulations. Open the simulation called "Sound". There are 5 tabs. Listen to a Measure Two Source Interference Listen with Interference by Reflection Varying Air Pressure Single Source Open the one called listen to a single source. PHET Sound Simulation Open the panel called "Measure" any 1. Using a experiment of your own design, measure the speed of sound. Record an data you obtain here. 2. Based on the speed you measured above, how long would it take for you to s away? hear thunder if you observed lightning and it was seen to be 1620 meter Open the panel called Two Source Interference 1. What do you suppose the light and dark bands on the "sound" emanating from the speaker represent? Enable Audio, change to Listener mode, not Speaker mode! Move the head of the listener up and down. What do you note about the locations where the waves intersect? Is there a location in which you hea What do you think is happening? Don't forget that sound is due to a change in local pressure. 2. r less sound? Open the panel called "Interference by Reflection" 1. Explore the affect of changing frequency on the reflected wave angle. Is there any affect? 2. Explore the affect of wall angle and wall position on interference pattern. Can you draw (roughly) a set up that shows interference that would not allow you to hear a certain frequency? In the space below show the speaker, the wall angle the wall position, and a location where you think the sound would "drop out" due to reflection.

Answer 1

1)

4 5 meters Simulation Time metes 0 1 2 3 0.0151 sec Stop Reset

it takes 0.0151s to reach 5m, so the speed of sound =

V) 0.0151 331.1m/s

2) To cover 1620m sound will thus take =

1620/331.1 = 4.89s

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1) The white bands represents highest pressure in sound waves and grey bands represent lowest pressure of sound wave.

2) Where two high pressure region meets the two pressures add up and make it a high intensity place. Where a high intensity pressure meats low intensity pressure, they cancel each other out and the audio almost goes out.

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1) Changing the frequency doesn't have any effect on the reflected wave angle.

2)

When the wall is at a distance which is an integer multiplier of the half of the wavelength of the sound and it makes 90º angle with the horizontal, then at the central line, the reflected wave and the incident wave cancel each other.