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Angle of Incidence vs. Angle of Reflection

October 23, 2011 by alison12 · No Comments · Uncategorized

Angle of Incidence vs. Angle of Reflection

Background Information:

Reflection is the change of direction of light. The angle a light ray makes is the same after reflection occurs as it is before reflection occurs. Reflection is the image seen when looking into a mirror, still water, or a polished surface. The reflected image seen will be the same as the object which is being reflected.

Aim:

To investigate what the relationship is between the angle of incidence and the angle of reflection.

Hypothesis:

The angle of reflection will equal the angle of incidence.

Materials:

  • One mirror
  • One power supply
  • One light box kit
  • One protractor
  • One A4 sheet of paper

Safety:

The light box could become hot, so be careful not to touch it.

Do not stick anything inside the power supply.

Safety goggles, lab coats and other safety equipment are not required for this experiment.

Variables:

Independent Variable: Angle of incidence

Dependent Variable: Angle of reflection

Controlled Variable: Mirror

Method:

  1. Draw on the A4 sheet of paper the normal.
  2. Set up all equipment such that the light reflects off the mirror as shown in the diagram below:

Science Focus 4

  1. Make the angle of incidence ten degrees. Measure the angle of reflection using a protractor.
  2. Repeat step 3, but increase the angle of incidence by ten degrees.

Results:

  Angle of Incidence Angle of Reflection

Attempt #1

10o 10o
20o 20 o
30 o 30 o
40 o 40 o
50 o 50 o
60 o 60 o
70 o 70 o
80 o 80 o
 

Attempt #2

10o 10o
20 o 20 o
30 o 30 o
40 o 40 o
50 o 50 o
60 o 60 o
70 o 70 o
80 o 80 o

 

 

Discussion:

There was only one credible trend in this experiment. This was that the measurements for the angle of reflection were the same as the angle of incidence. This occurred in both attempts. This happened because of the law of reflection, which states that θi = θr,. Simply put, the angle of reflection should always equal the angle of incidence. The reflected image seen will be the same as the object which is being reflected.

The type of reflection which occurred in this experiment in called specular reflection. Specular reflection is when a ray of light is coming from a single direction, and is reflected into a single direction going back. The angles made compared to the normal for both the outgoing and incoming rays should be the same.

Evaluation:

There was enough data collected to consider the results to be reliable. Both of the sets of results were the same, which proves further that the experiment was fair.

One advantage of the design was drawing the normal onto the A4 sheet of paper. This was beneficial because it helped me keep track of what the angle of incidence and the angle of reflection will be.

The method easily allowed me to collect relevant data to test my hypothesis. It was a good method because there was nothing at all complicated in it that is confusing. Something that could be improved is the simplicity. It would be better if I had tried some more complex experiments. However, the method worked well because it allowed me to answer my aim easily.

It would be interesting to try using different sized mirrors instead of just one small mirror. I do not know what would happen if I did that, so it would be interesting to try it out. Something else that would have been interesting to test is lights with different levels of brightness and measures them the same way as already done. This possibly could make the results vary.

Conclusion:

The hypothesis was supported. The angle of reflection equalled to the angle of incidence each time the experiment was done. The relationship between the angle of incidence and the angle of reflection was that they were the same.

 

 

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