Question

To achieve the greatest precision in finding the frequency f=1/T, does it make any difference to set the scope to display approximately one complete cycle across the screen and measure the period directly for one cycle, or se the scope to display several complete cycles and measure the time for N cycles, dividing the measured time by N to find the period of one cycle? In addition, is it better to choose as a reference point for your measurements the top (or buttom) of the waveform or the point where the waveform crosses zero? Justify your choice of method.

Answer 1

The measurement will be more accurate if you measure width of several complete cycles because if n readings are taken you can calculate averge of n measurements.

If each measurement has uncertainity

Average deviation from mean =

values for some readings will be on plus side and some will be negative and hence mean will be nearer to the actual value.

The refrence point where wave crosses zero amplitude is better since we can identify and take the horizontal reading accurately, exactly at that point. Moreover if we consider a maximum or a minimum point ,it may be spread out horizontally and hence it may be difficult to pinpoint exact maximum point or minimum ,especially if wave sinusoidal,rather than square in nature.