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The Laboratory

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All lab work should be completed in your course notebook and be recorded on the right side of the open notebook. If you come to the end of the page, you must of course turn the page over and continue writing on the back of the page on the right side of the page of the open notebook. Any accompanying sheets must be taped, glued, stapled or somehow attached to the lab notebook; scotch tape is always available in the room.


Lab RO1:  The Law of Reflection

Question:

What general principle could be made to describe how light reflects off a plane mirror surface?

Purpose:

To determine a general principle which describes the manner in which light reflects off a plane mirror surface.



A complete lab write-up includes a Title, a Purpose, a Data section (with labeled mirror and several labeled laser light paths), a Conclusion and a Discussion of Results. The Conclusion should include a generalized claim expressed in your own words that describes how light reflects off a mirror. The Discussion of Results should describe the evidence that supports the claim and includes several sentences that provide the logical reasoning that logically connects the evidence to the claim. Specific trials or results that justify your conclusion/claim should be identified.




Lab RO2: Images


Question:
How is a plane mirror image formed and what are the characteristics of an image?

Purpose:
To locate the image of an object as formed by a mirror and to describe the characteristics (size and location) of that image.

A Title, a Purpose, a Data section, a Conclusion/Discussion. The Data section should include the provided diagram with a located image, incident rays, reflected rays, extension lines, measurements of object and image distances, etc. The Conclusion/Discussion should include a description of how an image is formed and of the characteristics of an image (specifically, size and location); these are the claims. For each claim, there should be some evidence that is cited and some logical reasoning that explains how the cited evidence provides support for the claims.




Lab RO3: The Six Foot Man Problem

Question:
What length of plane mirror would be required in order for a six foot tall man to view his entire image in the mirror? Does the length depend upon how far away from the mirror that the man stands?

Purpose:
To use laser light in order to compare the portion of a mirror required by a six-foot man to view him/herself and to determine if the amount depends upon the distance between the man and the mirror.

A Title, a Purpose, a Data section, a Conclusion and a Discussion of Results should be included and clearly labeled. The Data section should include the provided diagram with both the empirical and the Ray Model approach. Measured distances (with units) should be clearly recorded for both approaches. The conclusion should provide a straight-forward answer to the two questions; this is the claim. The Discussion of Results should include a discussion of how the collected data (the evidence) lead logically to the stated conclusion. The Discussion section should also include an error analysis comparing the experimental results to the expected results; a percent error analysis might be included.




Lab RO4: Right Angle Mirror

Question:
At what location is the secondary image for a right angle mirror formed? What theoretical rule or general strategy could be stated to predict its location if given the object location?

Purpose:
To describe the location of the secondary image formed by a right angle mirror and to state a theoretical rule which could be used in predicting its location.

A Title, a Purpose, a Data section, a Conclusion and a Discussion of Results should be included and clearly labeled. The Data section should include the provided diagram with two sets of laser-guided incident and reflected rays showing the path of light from the object off both mirrors. The reflected rays (off the second mirror) should be extended by dashed lines behind the mirror; the image location should be marked and labeled. Class data should be included in the Data section and distinguished from individual data. The Conclusion should state the general rule for locating the secondary image of the object in a right angle mirror; this is the claim. The Discussion of Results should include the usual evidence/reasoning approach to the original questions posed by this lab. A student might record some labeled measurements - based on either individual data or class data - and explain the logical reasoning as to why those measurements lead to the claim that is made. In addition to the usual treatment of the logical connection between the evidence and the claim, the Discussion of Results section should include an error analysis.




Lab RO5: Finding Smiley Lab

Question:
How can a graphical representation of object distance and image distance be interpreted? What meaning can be gleaned from the graph?

Purpose:
To graphically represent the relationship between the object distance and the image distance (for a concave mirror) and to glean meaningful information from the graph.

A complete lab write-up includes a Title, a Purpose, a Data section, a Conclusion/Discussion. The Data section should include a table of dobject and dimage data and a plot of image distance vs. object distance (printed from Desmos). A best fit line should be included on the plot; strategic locations and distances should be marked (for subsequent reference in the Discussion section). The Conclusion/Discussion section should describe the relationship between the two quantities and extract a wealth of meaning regarding object-image distance relationships. Writing should be clear, specific and thorough.




Lab RO6: Magnification Ratio Lab

Question:
What object locations (relative to the surface of a concave mirror and expressed in terms of focal lengths) would result in the formation of images with magnification values of -1, -2, and -0.5?

Purpose:
To determine the object distances (expressed in terms of f) which would be required to produce an image magnification of -1.0, -2.0 and -0.5 and to use the results to determine the focal length of the mirror.

A complete lab write-up includes a Title, a Purpose, a Data section, a Conclusion and a Discussion of Results. The Data section should include a table of M , do, di and f values and labeled work shown for at least one f calculation. The Conclusion should identify the object distances (in terms of focal lengths: 2f, 3f, 4f, etc.) required for the specified M values and should state the focal length. The Discussion section should discuss how the focal length was determined, how the object distances (in terms of focal lengths) were determined and should include a thorough error analysis for each of the three trials.





Lab RO7: How Much? Lab

Question
What is the mathematical equation relating the angle in air to the angle in water for light refracting across the boundary from air into water?

Purpose
To state the experimentally-derived equation relating the angle in air to the angle in water for light refracting across the boundary between air and water.

A complete lab write-up includes a Title, a Purpose, a Data section, a Conclusion and a Discussion of Results. The Data section should include a table of data with column headings and units, a graph of sinΘair vs. sinΘwater.  Linear regression should be performed for the graph and the slope, y-intercept, regression constant and equation should be reported. Class data for the slope of the line should be recorded and subsequently used in your Discussion of Results. The Conclusion should include a claim that answers the question raised in the Purpose of the lab (as always). The Discussion of Results section should include an error analysis in which you evaluate the reliability of your data and of your equation. An error analysis should always respond to the question how well did I do? and provide evidence for the answer. In this lab, an error analysis should include a comparison of the experimentally-derived equation with the equation that would be expected based upon textbook reading; the comparison should include a percent error calculation (with work shown).




Lab RO8: The Unknown n Lab

Question: 
What is the index of refraction for the materials which comprise a variety of prisms?

Purpose: 
To determine the index of refraction of the unknown materials which comprise a variety of prisms.

A complete lab write-up includes a Title, a Purpose, a Data section and a Conclusion. The Data section should include an outline of at least two of the provided prisms;  the path of the laser light into, through and out of the prism should be indicated by light rays. Proper constructions and measured angles should be included on each diagram in an effort to determine the index of refraction of the material of the prism.  Measurements and calculations should be made (and clearly shown) for the entry and the exit boundary;  an average n value for each prism should be reported. The Conclusion should respond to the question raised in the Purpose of the lab (as always).



Lab RO9: A Critical Lab

Question: 
At what angle does refraction cease to occur in such a manner that light undergoes total internal reflection?

Purpose: 
To determine the critical angle for the water-air boundary and for the Lucite-air boundary.

A complete lab write-up includes a Title, a Purpose, a Data section, a Conclusion and a Discussion of Results. The Data section should include two diagrams - one for each boundary. The diagram should display a light ray approaching the boundary at the critical angle and the refracted ray at the appropriate angle. Critical angles should be recorded. The Conclusion should respond to the question raised in the Purpose. The Discussion of Results section should include a short error analysis and include percent error calculations for the two critical angle values.





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