... it were to hit a person's eye. The fan, a voltmeter, an ammeter and a cathode ray oscilloscope (C.R.O.) were all connected. This enabled me to adjust the power supply whilst getting an accurate reading of both current and potential difference. The C.R.O. was used to discern the time period of an individual rotation of a fan blade by counting five peaks and establishing the two similar ones as being the same blade. I then measured the distance between the two similar points to get a time period for the fan blade. I set the power supply at zero and then increased the voltage by 0.2v, keeping it as accurate as possible using the analogue voltmeter, and also took readings on the ammeter and the C.R.O. I continued to increase the voltage by the same increment and take the individual apparatus readings until I reached 3.0v. Above this value the level ...

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