Emily Travis Lab8 - lab report 8 PDF

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lab report 8...

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Name: Emily Travis E-mail address: [email protected] Laboratory 8 Report The purpose of this lab is to study and examine different image forming devices and how the lenses on those devices can affect what the viewer sees. Thin lens focal length will be calculated and aberrations observed. Also, what a Klerpian telescope and microscope records and sees will be observed.

Experiment 1 Maximally focused at approximately 9.5cm (object distance: 10.5cm, image distance: 9.5cm) Focal length: 4.9875 Check if moving the mirror a small distance along the track changes anything: Yes, movement along the track changes not only the focal strength of the dot but also the appearance of the dot at all.

Table 1 screen-lamp distance

measured xo

measured xi

calculated focal length: f = xoxi/(xo + xi)

inverted?

50 cm (1)

12.7 cm

37.3 cm

9.474

no

50 cm (2)

36.4 cm

13.6 cm

9.9

no

For the measurements of experiment 1 and 2 answer the following questions. ●

●

Do the two measurements from experiment 2 yield the same focal length within experimental uncertainties? Yes, the focal lengths are within 0.5 of each other. Explain how the measurements could be "off", given the way you measured the focal length. The measurements could be off because the measurements were taken with the naked eye only and there was no specific marker to indicate the exact positioning along the ruler so the measurements were naked eye guesstimates. Does the focal length obtained in experiment 1 agree with the focal length obtained in experiment 2 within experimental uncertainties? They are not the same focal length so I am assuming that no they did not agree.

● ●

In experiment 2, did you observe inverted or upright images? They were upright but the images were reversed (circle on opposite side in reflection) Did you observe aberrations? I don’t think so

Observation 1 Describe what you observe as the lens is moved away from the screen. Identify the aberration. First, when the lens is rotated, the vertical line of the cross is significantly blurred while the horizontal line is only slightly blurred. When the lens is backed away from the screen, the horizontal line becomes thicker and clearer while the vertical line blurs almost to where it is indistinguishable. Observation 2 Describe your observations. Two distinct images of the cross are seen on the lens - one is larger than the other and one is inverted while the other is upright. Which surface of the lens acts as the mirror producing the upright image? Does this image appear behind or in front of the lens, as seen from the side of the lamp? The side of the lens facing the lamp produces the real image of the cross. It appears in front of the lens as seen from the lamp. Which surface of the lens acts as the mirror producing the inverted image? Does this image appear behind or in front of the lens, as seen from the side of the lamp? The opposite surface acts as the mirror producing the inverted image. It appears behind the lens as seen from the lamp. Observation 3 Describe features of the image (orientation, aberrations). The image on the left looks real and upright, as though we are looking at it with our own eyes. The image on the right is much more magnified and is inverted. The moon subtends an angle of 0.5o at the eye. If it is looked at through the telescope at the moon, what would be the angle subtended by the moon's image ? 18 degrees Observation 4 Describe features of the image (orientation, aberrations). To decide on the orientation, look at the image of another target below. The images are inverted and backwards. The images are also warped because of the shape of the lens....