The pre-lab was marked out of 6 with one mark for each of the following:

• rate of change = -6dB per doubling of distance
• correct computation of wavelength
• correct value of y for first minimum
• signal level increases as y increases
• correct value of y for first maximum
• correct table of values of y for first 3 minima and maxima (use of approximation formula was marked correct although errors are high for 3rd and higher maxima/minima)