PHY 2049L
Lab 9

Lenses

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Updated: 8/09/2009
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Prelab

Answer all 9 questions on pages 417 and 418 of the manual.

Note that the lab manual (and the handout) use a different convention for identifying the object (p instead of s) and image (q instead of s') positions. You can use the notation we use in lecture for your calculations if you wish.

Comment

The procedure, data tables, and questions are all on a handout. I link in a copy of the procedure and a sample data table below, but the questions vary in detail from semester to semester so you will get the actual data table and questions in the lab.

As described in the handout for this lab,

we will make four sets of measurements of the location and size of the image formed of a slit for each of two lenses. The data are taken in pairs, using the fact that a solution for "p" and "q" is also a solution for "q" and "p". The two positions that interchange image and object distance are called conjugate points. Note that there is also a place on the data sheet for an "estimate" of the focal length that is made using the overhead lights in the lab. This estimate assumes that the lights are at infinity so the image forms at the focal point.

Apparatus

optical bench, showing screen, lens holder, and light source

Photo of the optical bench, showing screen holder (left) that you will fill with a sheet of paper, lens holder (middle), and light source. The bar is a calibrated ruler, but you can also use a ruler to make the required measurements.

The photo below shows a closeup of the light source taken from the other side of the table. Notice the relative location of the arrow slit and the lamp.

close-up view of light source and slit mounting

 
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?? Contact me if you have any questions.