3B Scientific SEK Optics - Manual (Page 43)

Exercise
Examine the way selected beams of light react when passing through a focusing lens!
What do we need?
1 Optical lamp
with power supply unit
1 Base plate
1 Screen
1 Focusing lens (flat design)
1 Single-slot aperture
1 Three-slot aperture
1 Mask
additionally required:
1 Ruler
Conducting the experiment
1. Place the optical lamp on the left side of the base plate, so that the light emerges parallel to the
right!
2. Place the screen in front of the optical lamp, so that it is flush with the right side of the base plate!
3. Place the focusing lens as marked on the mask!
4. Insert the three-slot aperture into the aperture holder! Determine the focal point of the lens and
mark it on the mask!
5. Replace the three-slot aperture by a one-slot aperture. Generate a beam of light parallel to the op-
tical axis by changing the position of the optical lamp. Observe the beam of light after passing
through the lens!
Draw a sketch on the mask!
6. Generate a beam of light, which passes through the centre of the lens. Observe the beam when it
passed through the lens! Draw a sketch!
7. If the path of light is reversible, it is possible to tell how the beam of the focused light is refracted.
Describe the result!
8. Name examples where focusing lenses are used!
9. Describe how to determine the focal length of a focusing lens!
ELWE Physical experiments for education in natural science and engineering
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1 SEG - OP 4.3 Path of Rays through a Focusing Lens