Your work on this assignment is good.
Let me know if you have specific questions on any of these ideas.
Experiment 28: Image Formation
In this experiment I had to use two candles that were at my apartment because I was not given two candles in my lab kit. The candles were approximately 9 cm in length. The convex lens I used was 3.3 cm in length. I used a wall in the apartment for the spot light. Focal length of this lens was about 7.25 cm by forming a sharp image of a distant candle and measuring the focal distance directly.
Create images of a single light source
Distance Light Source was from Lens (cm) Distance from the Center of Lens to the Screen where imagine was Sharpest (cm)
20 5.3
30 5.5
40 5.0
50 3.8
The distance seems to be out of place. The student had some problems in measuring the distance for some of these, but later rigged up a better stand for the lens for more accurate calculations.
Create images of a double light source
Distance between the two candle flames: 7 cm
- This may cause a difference in the distance between the two images displayed on the screen because they are farther than several centimeters suggested in the lab instructions.
Distance Light Source was from Lens (cm) Distance between imagines (cm)
20 2.3
30 1.5
50 .8
When I placed a note card in front of the left candle, the image on the right side of the screen disappeared because when the rays from the left candle flame hit the convex lens and then are displaced to the opposite side, or the right side on the screen. This is similar to how our eyes work. The image is flipped upside-down due to the image hitting our cornea. Look to Figure A. for a picture of this example:
Figure A
The Spotlight
The student had some trouble with this part of the lab. The spotlight distance from the center of the lens that the student measured was approximately 3 meters. To make the image somewhat sharp the table had to be moved back. The image was still somewhat dark though, but this is the best that was shown on the wall.