Lens Lab

Lens Lab

Purpose:

In this activity you will be learning how the location and size of an image depends on the location and size of the object.

Info:

  • Lab setup for the live part:  Copy this into your lab lab book.



  • Lab Set up for the simulated part:  The candle on the left of the lens is your object and the candle that you see on the right is the image of the candle that is created by the lens.  Also copy this into your lab book.


Procedure:

Part 1:  Live Part

  1. When directed to do so by your teacher, go back to one of the lab setups in the room and collect 8 data points for do and di.  Make a data table to record your values and record all the values in cm.

  2. Set your candle the 5 cm mark on your meter stick.  You can read the exact location by looking at the pointer on the bottom of the candle holder.  In the picture below the pointer is at 44.5 cm.



  3. Place your lens at some distance greater than 15 cm from the candle.  Adjust the location of the screen until the sharpest image of your candle comes into view.  Record the distance from the lens to the candle (do) and the distance from the lens to the screen (di).

  4. Use Logger Pro to graph the distance to the image (y) vs. the distance to the object (x).

  5. To curve fit your data follow the instructions in the picture shown below.  Then put your "A" Value on the board.



  6. Copy the graph into your lab book and give a sentence or two description of what you found.  Also give sources of error for this part of your experiment.

Part 2:  Simulation:  Changing do

  1. Open the simulation program found here in a new tab.

  2. Before you start the lab, hit reload on your browser to make sure you reset the program to its default parameters and at this point, don't change the height of the candle or the focal length of the lens, but record the focal length and height of the candle in your lab book.

  3. Create a data table that gives the distance to the object (do), the distance to the image (di) and the height of the image (hi).  Give enough rows for 8 different locations.

  4. Record the initial values for the do, di and hi in the first row of your table.

  5. Start the simulation and then pause it every so often to get new data points.  If you candle moves inside the focal point or if the image goes off the screen to the right, wait until the candle moves back to a good location before pausing the program again.

  6. Use Logger Pro to graph the distance to the image (y) vs. the distance to the object (x).

  7. To curve fit your data follow the instructions in the picture shown below. 



  8. Now plot a graph of height of the image (y) vs. distance to the image (x)

Part 3: Simulation: Changing ho

  1. Before you start this part of the lab, hit reload on your browser to make sure you reset the program to its default parameters and at this point.

  2. Create a data table that gives the height of the object (ho), the distance to the image (di) and the height of the image (hi).  Give enough rows for 8 different heights.

  3. Record the initial values for the ho, di and hi in the first row of your table.

  4. Change the height of the candle and record a new row of data.  Repeat this for 8 different candle sizes.

  5. Use Logger Pro to graph the distance to the image (y) vs. the height of the object (x).

  6. Use Logger Pro to graph the height of the image (y) vs. the height of the object (x).

Part 4:  Simulation: Changing f

  1. Before you start this part of the lab, hit reload on your browser to make sure you reset the program to its default parameters and at this point.

  2. Create a data table that gives the focal length of the lens (f), the distance to the image (di) and the height of the image (hi).  Give enough rows for 8 different focal lengths.

  3. Record the initial values for the f, di and hi in the first row of your table.

  4. Change the focal length of the lens and record a new row of data.  Repeat this for 8 different focal lengths.

  5. Use Logger Pro to graph the distance to the image (y) vs. the focal length of the lens (x).  Instead of curve fitting this graph and copying it into your notebook, just give a sentence that tells how di changes with f.

  6. Use Logger Pro to graph the height of the image (y) vs. the focal length of the lens (x).  Instead of curve fitting this graph and copying it into your notebook, just give a sentence that tells how hi changes with f.


Things to have in your lab book:

  • Purpose

  • A picture of the lab set up for the live part and for the simulation.
     
  • Data Tables for all parts

  • Graphs for each set of data for part 1, 2 and 3.

  • Description of your graphs for part 4

  • Conclusions and sources of error

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