#4 Standing wave:

Objective: 

The objective of this lab is to gain knowledge and understanding of standing waves driven by an external force. Resonant conditions for standing waves on a string will be investigated.

Procedures:

1.      Measure and record length and mass of string.

2.      Tie the string to two clamps. Tie about 200 g on the end of pulley.

3.      Attach the string to the wave driver, set up the function generator as instructed.

4.      Adjust the frequency to reach the fundamental mode, record frequency and number of nodes. The length participating the oscillation must be recorded as well. Repeat and record information under different node numbers.

Results:

       The recorded values as shown:

Frequency / Hz	12.45	24.35	40.35	49.35	65.35	87.35	102.35
Node to node / cm	168.5	88.5	57.5	42.5	29.5	26.5	22.5
Number of nodes	2	3	4	5	6	7	8
Wave length / cm	337	177	115	85	59	53	45
Wave speed /ms-1	41.9565	43.0995	46.4025	41.9475	38.5565	46.2955	46.0575

       Average wave speed is 43.4736 m/s, and its standard deviation is 2.9486.

       The string is 195.3 cm in length and 2.36 g in mass, thus the density is 1.224 x 10^-3 kg/m. By a tension of nearly 0.2x9.8 = 1.96 N, the theoretical speed is calculated as 40.0163 m/s

       Percent difference is (43.4736 - 40.0163) / 40.0163 x 100 = 8.639 %.

       The uncertainty in measuring the mass is 0.01 g and length is 0.2 cm, thus the uncertainty in density is 0.265 x 10^-3 kg/m. Therefore the error in speed should be with in (45.2083-43.4736) / 43.4736 x 100 = 3.990%, and 8.639 % exceed that value.

      

Discussion:

       Due to the technical difficulty and time limitation we were unable to perform the latter part of the lab. From the data of the first lab, the data is considered a little over expected error but as it is still within ten percent, the experiment is not a total failure.
       To my lovely lab partner: Where did you guys get the data of part II...