Higher Physics

Radiation and matter - Activity 24

Photodiode - photovoltaic mode

Aim - To measure the frequency of an a.c. supply using a photodiode in photovoltaic mode.     Instructions 

The photodiode is placed near a 12 V lamp which is connected to an a.c. supply. The y shift on the oscilloscope has been adjusted to produce the trace shown.
The y- gain and time base are increased by clicking on the right side of the knob. They are decreased by clicking on the left side of the knob.

 
  • Adjust the y gain and the time base to obtain a clear trace.
  • Calculate the frequency of the a.c. supply from the trace produced. (Remember that the intensity of the lamp peaks twice for each cycle of the a.c. supply)

 
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