SC 130 Laboratory 10: Reflection and refraction

Hypotheses

There exists a mathematical relationship between the distance of an object in front of a mirror and the distance of the image "behind" the mirror.
There exists a mathematical relationship between the angle of angle of sight for an object in air and the angle of sight for an object seen below the surface of the water. Theory: light rays bend when entering/leaving water and passing into the air.

Procedure

Work in teams of three to four students - you will need the extra hands during the refraction portion of the laboratory.

Reflection

Place an object in front of the mirror. Measure the distance from the object to the mirror. Measure the apparent depth of the image of object "behind" the mirror. Record the distances in centimeters.

[d] [t] Data table one: reflection

Reflection data
Object distance (x)/cm	Image depth (y)/cm

Refraction

For the first part of this section make measurements with the dish pan empty - no water. Put a penny or other coin in the corner of the dishpan.

Seen obliquely, the penny is in the far corner

Measurements will be made along a diagonal away from the coin.

Seen from above, the measurements are made along the diagonal of the dishpan

Measurements of the angle will begin directly over the coin.
Angle measurements will be repeated every ten centimeters.
Angle measurements should start at zero directly over the coin.

Make measurement every ten centimeters as one moves away from the coin

Use a pencil, pen, or other stick to "aim" at the coin.
Measurements all have to be made from the exact same height. A height of about 50 cm should work. A meter stick will help determine the protractor height.
Measure the angle by reading the protractor as indicated by the arrows in the diagram above.
Repeat measurements every 10 cm as you move away from the coin.
Keep going until the edge of the dishpan blocks the view of the coin. At this point remove the penny from the dishpan, take away the dishpan, and put the penny back down in the exact same location on the table.
Continue recording angles until you are about two meters away from the penny. Record the distance and the angle.
For the second part of this laboratory, fill the dish pan with water until almost full.
Repeat your measurements starting from directly above the coin. Continue every 10 cm to make angle measurements until you cannot see the coin any longer.

When finished, carefully empty your water either outside or in a sink.

[d] [t] Data table two: refraction

Refraction data
Distance from coin/cm	Angle to coin in air (x)/degrees	Angle to coin in water (y)/degrees

[g] Graph: xy scattergraphs

Make two xy scattergraphs using spreadsheet software, one for the reflection data and one for the refraction data.

[a] Data analysis

If the graphs indicate that a linear relationship exists for either reflection and/or refraction, find the slopes and intercepts. Use either the LINEST function or, if you know how and wish to do so, use the SLOPE and INTERCEPT functions. If one or both of the graphs suggest either a non-linear or no relationship, note that as well. If there is a relationship, either linear or non-linear, then a mathematical relationship does exist.

=LINEST(y-values;x-values;0)

[c] Conclusion

Discuss the findings. Discuss whether the hypotheses confirmed or disconfirmed. Discuss also any difficulties you encountered.

The lab will also be marked on grammar [G], vocabulary [V], organization [O], and cohesion [C].

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