A node is a point where the string does not move. An antinode is a point where the amplitude is greatest. You can measure the wavelength as the distance separating 3 consecutive nodes (see the diagram on the right).
Activity 1: You will Measure the exact length of a piece of the braided string provided by your instructor. Measure the mass of the string and calculate the linear density, (mass/length). Record your result:
Activity 2: In this Activity, you will collect data on how the wavelength and period of a wave are affected by changing the frequency. The frequency is set by means of a sine wave generator.
a) As shown in the figure below, your experimental setup consists of the Sine Wave Generator and pulley (positioned about 1(X) cm apart), a string vibrator, and masses. Run the string over the pulley, and hang about 150 g of mass from it.
b) Turn on the sine wave generator and turn the amplitude knob all the way down (counter-clockwise). Connect the sine wave generator to the string vibrator using two banana patch cords. Polarity does not matter.
c) Set the amplitude knob about midway. Use the Coarse (1.0) and Fine (0.1) Frequency knobs to adjust the vibrations so that the string vibrates in several stationary segments (a standing wave). Adjust the driving amplitude and frequency to obtain a large-amplitude wave, but also check the end of the vibrating blade: the point where the string attaches should be a node. It is more important to have a good node at the blade than it is to have the largest amplitude possible.
d) Adjust the frequency so that the string vibrates in 1, 2, 3, 4,... , 8 segments, then record the frequency and measure the wavelength for each standing wave and record them in the data table.
Activity 3:
a) Calculate the period. Record the results in the data table above.
b) Using Excel, make a coordinate (scatter) plot of the wavelength vs period for all of the standing waves you observed. Add all appropriate titles and labels, and then add a linear trendline with the equation displayed on the chart.
c) Give an equation relating the wavelength A and period T that best describes your observations.
d) If the period increases by a factor of two, what happens to the wavelength?
e) Propose a physical meaning for the slope of the graph of wavelength versus period.