3B Scientific SEK Optics - Manual (Page 49)

Exercise
Examine how narrow beams of light react when they pass through a combination of lenses!
What do we need?
1 Optical lamp
with power supply unit
1 Base plate
1 Screen
1 Focusing lens (flat design)
1 Dispersing lens (flat design)
1 Three-slot aperture
1 Mask
additionally required:
1 Ruler
Conducting the experiment
1. Attach the mask to the screen!
2. Place the optical lamp on the left side of the base plate, so that the light emerges parallel to the right!
3. Place the screen in front of the optical lamp, so that it is flush with the right side of the base plate!
4. Place the focusing lens on the screen as marked on the mask!
5. Insert the three-slot aperture into the aperture holder and initially determine the position of the focal
point for the focusing lens!
6. Measure the focal length of the focusing lens! Enter the values in the table!
7. Determine the focal length for the dispersing lens! Place the dispersing lens onto the spot marked
with broken lines!
8. Calculate the focal length for the combined lenses!
9. What do you conclude is the effect of the two lenses when they are combined?
10. Check the calculated focal length by testing! Use the three-spot lens to check your calculations
with the aid of the three parallel beams of light! Draw the beam of light on the mask when both
lenses are applied!
11. Exchange both lenses and observe the three incident parallel beams of light!
12. Name appliances in which combinations of lenses are used!
ELWE Physical experiments for education in natural science and engineering
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1 SEG - OP 4.6 Paths of Rays through a Combination of Lenses