3B Scientific SEK Optics - Manual (Page 63)

Exercise
Examine how to correct short-sightedness!
What do we need?
1 Optical lamp
with power supply unit
1 Base plate
1 Screen
2 Lenses “+50”
1 Lens “ −100”
1 Aperture holder
1 F aperture
1 Mask
additionally required:
1 Ruler
Conducting the experiment
1. Attach the mask to the base plate!
2. Place the optical lamp on the left side of the base plate, so that the light emerges conically to the
right!
3. Place the screen on the right side of the base plate!
4. Place the “+50” lens in front of the optical lamp and the aperture holder with the F aperture in front
of the lens!
5. Place the second “+50” lens between the aperture holder with F aperture and the screen! (In com-
bination with the screen this lens forms the eye!)
6. Focus the F!
7. In a short-sighted eye the image is generated shortly before the retina and the image is not
focussed! Move the screen 5 cm along the optical axis away from the eye lens!
8. Place the “
−100” dispersing lens in front of the eye lens! If necessary, correct the distance between
the dispersing lens and the eye lens!
9. Sketch the beam of light!
10. Name the features of the image that a short-sighted person obtains with glasses (dispersing
lenses)!
ELWE Physical experiments for education in natural science and engineering
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1 SEG - OP 5.2 Short-sightedness and its Correction