A student uses a ripple tank to test the equation wave speed = frequency x wavelength, by measuring the wavelength produced at several different dipper frequencies. Her results are: frequency = 2 Hz, wavelength = 40 cm; frequency = 4 Hz, wavelength = 20 cm; frequency = 6 Hz, wavelength = 20 cm; frequency = 8 Hz, wavelength = 10 cm; frequency = 10 Hz, wavelength = 8 cm.
Figure (to be drawn): A table of results: frequency in Hz (2, 4, 6, 8, 10) against measured wavelength in cm (40, 20, 20, 10, 8).
(a)For the results at 2 Hz, 4 Hz, 8 Hz and 10 Hz, calculate the speed of the wave in each case (convert each wavelength to metres first), and show that the wave speed is approximately constant for these four results.(3)
(b)Identify which one of the five results is anomalous, and calculate the wavelength that would have been expected at that frequency for consistency with the rest of the data.(3)
(Total for Question 19 is 6 marks)