# Curved Mirror Lab

 Materials: Computer and School Network Time Allotment: 4 Class Days

### Purpose:

The purpose of this lab is to investigate the qualitative and quantitative relationship between the object distance and image distance, the object height and image height, and the magnification and object distance for a concave and convex mirrors.

### To begin this lab:

1. Log on to the student server in the usual manner
2. Open the Multimedia folder; then open the Hypercard application.
3. Once the Hypercard is opened, chose Open... from the File menu.
4. A directory dialogue box should appear. Navigate through the Physics Stacks directory and find the file titled Curved Mirrors; open this stack by double-clicking on its icon.
5. Click anywhere on the first card in order to navigate to the Concave Mirrors card.

### Part I - Qualitative Relationships:

This HyperCard stack contains two cards which can be used to investigate relationships for concave and convex mirrors. There is an upright arrow (representing the object) which can be moved about the principle axis by clicking and dragging it. Once you cease dragging it and let up on the mouse button, an image of the object arrow is drawn. The image's height and distance from the mirror are dependent upon the object distance (and the object height, which is not alterable in this simulation). A butoon at the bottom of the monitor allows you to study both concave and convex mirrors. In Part I, you will investigate the relationships between these three variables.

1. Using several well-written sentences, describe what happens to the image distance as the object is dragged from point W (beyond the center of curvature) to point X (between the center of curvature and the mirror) for a concave mirror.

2. Using several well-written sentences, describe what happens to the image height as the object is dragged from point W (beyond the center of curvature) to point X (between the center of curvature and the mirror) for a concave mirror.

3. Using several well-written sentences, describe what happens to the image distance as the object is dragged from point W (far from the mirror) to point X (close to the mirror) for a convex mirror.

4. Using several well-written sentences, describe what happens to the image height as the object is dragged from point W (far from the mirror) to point X (close to the mirror) for a convex mirror.

5. If an object is located in front of the focal point of a concave mirror, how can the image size (reduced, enlarged, same size) and location (closer to mirror, farther from mirror, same distance from mirror) be described?

6. Make a generalization describing the size (reduced, enlarged, same size) and approximate location (closer to mirror, farther from mirror, same distance from mirror) of an image formed by a convex mirror regardless of the object location.

7. A dentist would like to use a mirror to view a magnified image of your back molar. What type of mirror should she use and where should the object be located relative to the focal point of the mirror? Explain the rationale for your decisions.

### Part II - Quantitative Relationships:

This HyperCard stack allows actual measurements of object distance and image distance to be made for both types of mirrors. Once the object arrow is dragged to a new location and the mouse button is released, new values of d-object, h-object, d-image and h-image are calculated and displayed in the appropriate fields. In Part II, you will investigate the mathematical relationships between the important variables for object distances which are greater than one focal length. (Never place the object in front of the focal point in Part II.) Be sure to use object distances which range from way far away to very colse to one focal length; the majority of your measurements should be made for object locations between C and F. You will repeat your measurements for a concave mirror for two different focal lengths. Once you have collected values of h-object and h-image, compute the magnification of the image (i.e., h-image/h-object). After completing the data collection and calculations, procede to Part III where you will graphically display and interpret the data.

Table A - Concave Mirror (first focal length value)

Focal Length = __________ cm

 d-object (cm) d-image (cm) h-object (cm) h-image (cm) Magnification ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________

Table B - Concave Mirror (second focal length value)

Focal Length = __________ cm

 d-object (cm) d-image (cm) h-object (cm) h-image (cm) Magnification ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________ ________

1. Based on the data above, what types of object distances will lead to large magnification values? Explain.

2. Based on the data above, where must the object be placed to obtain a magnification of 1.0? Explain.

### Part III - Graphical Interpretation:

In Part III, you will use the Graphical Analysis software program (available on the school's server) to construct and interpret graphs of the data. For both data sets construct a graph of d-image vs. d-object (the image distance values are plotted along the vertical axis). Once the data is plotted, draw a smooth, curved line through the data points. Print both graphs and use them to answer the following questions. Clearly label the focal lengths on both graphs and turn them in with your lab report.

1. On both graphs, there should be an x-axis value for which data points approach yet never reach. Draw a vertical line on the graphs at this x-axis value.
2. There should also be a y-axis value for which data points approach yet never reach. Draw a horizontal line on the graphs at this y-axis value.
3. For each graph, compare the x- and y-coordinates for the two lines which you just drew. Compare these values to the focal length of each mirror. State a generalization which describes the mathematical relationship between the focal length and the image distance as the object distance approaches large values.

State a generalization which describes the mathematical relationship between the focal length and the image distance as the object distance approaches one focal length.

4. Identify on the plotted lines of both graphs the location where the object is at the center of curvature. Place a dot at this point. and label it as d-object = 2*f.
5. What do you notice about the relationship between the object distance and the image distance when the object is located at the center of curvature? What should you notice? Explain fully.

### Conclusion:

Use a well-written paragraph to summarize what you have learned about the qualitative and quantitative relationship between the object distance and image distance, the object height and image height, and the magnification and object distance for a concave and convex mirrors. Do a bang-up job!