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Optics
Fibroptonic
Ref : 202 012
1 Purpose
To use the properties of the photoresistor to examine a white light spectrum.
2 Experiment no. 22
Projector
gratting
ENGLISH
FIBROPTONIC
2.1 Equipment:
•
Slide projector
•
1mm wide slit cutout in 5x5 cm size cardboard.
•
Diffraction grating of 140lines/mm
•
Photoresistor module
•
White screen (of cardboard, for example)
•
Multimeter, which can be used as an ohmmeter (to measure the resistance)
2.2 Set-up and experiment:
•
Place the vertical slit in front of the slide projector and adjust the focus so that a
clear image of the slit is obtained on the screen located at about 1 meter from the
projector.
•
Fix the diffraction grating well against projector (lines from the diffraction grating
must be parallel to the slit).
•
Intercept the 1
st
order spectrum using the photoresistor (figure 24). Attach a small
slit cut in a black adhesive tape (width: 0.5 to 1 mm depending on the lighting
power of the source and the distance between the projector and photoresistor) on
the photoresistive cell.
•
Connect the ohmmeter to the black and yellow terminals of the photoresistor.
slit
diffraction
Figure 24: Examining a white light spectrum with a photoresistor.
SPECTROSCOPY
Order 0
Order 1
66
SHEET
10
Ohmmeter
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