Lab 12 Resonance 2020 Lone Star College. All Rights Reserved. Name: Objective To observe the properties of resonance tubes. Materials _ - Varlable length resonance tube - Water - 1024 Hz tuning fork - 2048 Hz tuning fork - Rubber mallet Procedure: In this lab, you will send a sound wave down a tube almost full with water. You vary the length of the air column (above the water level) in the tube by changing the level of water in the tube until you create a standing wave that amplies the sound. Each frequency will create an antinode at the tube opening and a node at the water surface for four lengths. Each length corresponds to a different harmonic. 1. Before starting the experiment, you should compute the theoretical values of the tube lengths where you are creating standing waves. Using an estimated speed of sound of 345 unis, compute the expected tube lengths using the following equation for two different frequencies, 1024 Hz and 2048 Hz: f..=n(w'4L) =1,3,5,... When n = 1 f. = (w'4L); L = was) f=1024 Hz, v=345 m; L = 3452(4 * 1024) = 0.034 m = 3.4 om f=2048 Hz, v=345 mm; L = 345f(4 * 2048) = 0.042 m = 4.2cm 6. Lab 12 Resonance 2020 Lone Star College. All Rights Reserved. Compute the theoretical tube lengths required for the rst, third, fth, and seventh harmonics (n= 1, 3, 5 and 1') at each of the two frequencies. (These lengths will give you approximate points where you should get resonance) Record these theoretical values in Table 1. Fill the resonance tube with water. Practice varying the height of the tube by moving the water tube up and down. The water level in the tube will rise when the tub is above the water line, and it will fall when the tube is below the water line. Using the rubber mallet, hit the tuning fork. With the tuning fork oscillating, hold it so that the side ofthc tuning fork is directly over the top of the tube. Note: - Do not hit the tuning fork with anything other than the rubber mallet. - Hold the tuning fork as close to the opening of the tube as possible, but do not touch the tube. Vary the length of the tube until you hear a standing wave amplication of the tuning fork for the rst harmonic. Use your previously calculated theoretical values of tube length to help you find the approximate location of the water level. Record the actuachperimental length of the tube in Table 1 below. Since this is an online lab, watch \"Resonance - Data Collection Video: and record the actual lengths of the tube corresponding to 4 harmonics for each tuning fork and record the data in Table 1 below. Compare the Theoretical values with experimental value of the length of tubes. TABLE 1 - Experimental Length of Resonance Tubes: 14 points Exper. 15t Harmonic 3rd Harmonic 5'\" Harmonic 7'\" Harmonic Theor Exp Theor Exp Theor Exp Theor Exp 1024 Hz 2048 Hz Lab 12 Resonance @ 2020 Lone Star College. All Rights Reserved. 1. For each of the "Experimental" lengths above, calculate the speed of sound using the equation in procedure stepl above. Record the results in Table 2 below. Example: f1 = (v/4L) v=fi * 4 Llexp where "fi = 1024 Hz" and "Llexp " is the experimental length from the above table for Ist harmonic. TABLE 2 - Speed of Sound 7 points 1s' Harmonic 3rd Harmonic 5th Harmonic 7th Harmonic 1024 Hz 2048 Hz QUESTIONS: Answer the following post-lab questions. 2 points each 1. What are the possible reasons for theoretical values being different than the experimental values for the length of the tubes? 2. How close is the speed of sound to the expected value? What can account for the difference