f= 2L tuning fork where L is the length of N loops. Because the string is being driven at the same frequency as une tuning fork, the frequency of the tuning fork producing the standing waves is also given by (7). (7) In the experiment a string is attached to one tine of an electrically-driven tuning fork. The other end of the string passes over a pulley to a weight hanger. (Refer to Figure 2.) The vibrating tuning fork sets up standing waves on the string and the amplitude of these waves can then be maximized by changing the weight on the weight hanger or by moving the entire tuning fork assembly toward or away from the pulley. Figure 2. The apparatus set up with standing waves on the string. 6. In the calculation of the experimental frequency from (7), the mass associated with the length of the string hanging over the pulley was not taken into account. Suppose that the length of string hanging over the pulley is 20 cm. By what percentage does the experimental value of the frequency change when the hanging mass is 100 grams?