## Refraction and Lenses Notebook Labs

The following items should be in the Refraction and Lenses portion of your notebook. They should be clearly organized and easy to find. Use an organizational system and label all work. Each lab will be graded separately.

### RL1. Refraction Action Lab

Question:
When does light refract? Why does light refract? When does light not refract?

Purpose:
To describe when light refracts, why it refracts and when light does not refract?

A complete lab write-up includes a Title, a Purpose, a Data section, a Conclusion /Discussion section. The Data section should include an organized record of a collection of refraction observations and activities. The Conclusion/Discussion section should respond to the three parts of the purpose, providing an answer to each of the three questions. For each answer, evidence and/or examples from the Data section should be cited in support of the answer.

### RL2. Direction of Bending Lab

Question:
What rule could be developed to describe the direction of bending of a light ray as it crosses the boundary between two transparent media?

Purpose:
To determine the principle which would predict the relative direction of bending of a light ray as it crosses the boundary between two media (in either of the two directions).

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 trace of two or more prisms (rectangular or triangular) and the path of laser light from air, into, through and out of the prism. Normal lines should be constructed and the relative direction of bending with respect to the normal line should be discussed. The Conclusion should include a statement of the rule(s). The Discussion of Results section should make explicit reference to the diagrams in the Data section and discuss the logical connection between the evidence and the conclusion.

### RL3. Least Time Principle Lab

Question:
How do the ratios of light speed compare to the ratio of angles for light passing from one medium to another?

Purpose:
To use the least time principle and an analogy to a life guard's most efficient path in order to relate the ratio of light speeds to the ratio of angles of incidence and refraction.

A complete lab write-up includes a Title, a Purpose, a Data section, and a Conclusion. The Data section should include the provided tables and an additional table which summarizes the results of the three trials. The Conclusion section should respond to the question raised in the purpose and state an equation relating the two ratios.

### RL4. 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 sinQair vs. sinQwater. 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 respond to 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 which would be expected based upon textbook reading.

### RL5. 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 nvalue for each prism should be reported. The Conclusion should respond to the question raised in the Purpose of the lab (as always).

### RL6. R and R Lab

Question:
What is the effect of increasing the angle of incidence upon the amount of reflection and refraction which occurs for light when it reaches a boundary?

Purpose:
To determine the effect of increasing the angle of incidence upon the relative amount of light which undergoes reflection and refraction at a boundary between Lucite and air.

A complete lab write-up includes a Title, a Purpose, a Data section and a Conclusion/Discussion section. The Data section should include an outline of the hemi-cylindrical Lucite disk and should somehow document the results of your investigation. This section should be labeled, visual and purpose-related (purposeful). The Conclusion/Discussion section should use organized and complete sentences to respond to the question raised in the Purpose of the lab. Conclusion should be supported by making specific reference to observations in the Data section.

### RL7. 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.

### RL8. Exploring Lenses Lab

Question:
How would you describe the images formed by a converging and a diverging lens for nearby and distant objects?

Purpose:
To describe the orientation and relative size of the images produced by a converging and a diverging lens for nearby and distant object locations.

A complete lab write-up includes a Title, a Purpose, a Data section, a Conclusion/Discussion. The Data section should document the observations of relative size and orientation in an organized manner; a table would be a wonderful idea. The Conclusion/Discussion should include an organized paragraph in which you respond to the question raised in the Purpose of the lab.

### RL9. The L•O•S•T Art of Image Description Lab

Question:
How do the characteristics of images formed by converging lenses compare for various object locations?

Purpose:
To describe the relative location, orientation, size and type of the image produced of an object by a converging lens when the object is located at four strategic locations along the principal axis.

A complete lab write-up includes a Title, a Purpose, a Data section, a Conclusion/Discussion. The Data section should include a table in which you identify the observed (LOST) characteristics of the images for object positions beyond the 2F location, at the 2F location, between the F and 2F locations and inside F. The data table should be accompanied by a diagram depicting the strategic locations. The Conclusion/Discussion should include an organized paragraph in which you respond to the question raised in the Purpose of the lab.

### RL10. The Lens Equation Lab

Question:
How can carefully-collected data and a graphical analysis of the data be used to derive the lens equation?

Purpose:
To experimentally derive the lens equation using collected data and methods of graphical analysis and linear regression.

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 object distance and image distance data; column headings and units should be included. Values of 1/dobject and 1/dimage should be calculated and a plot of 1/dimage vs. 1/dobject should be constructed. Linear regression should be performed for the graph and the slope, y-intercept, regression constant and equation should be reported. The Conclusion should respond to 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 equation, relate the equation to the theoretically expected equation and determine the focal length from your y-intercept. The logic associated with the focal length calculations should be fully explained.