science - relection and incidence cau

Reflection Experiment

Background Information
The law of reflection states that the angle of incidence will be equal to the angle of reflection. I.e. the angle that the light strikes the reflective surface at will be the same as the angle that it leaves it at.

Aim
To investigate the law of reflection and evaluate its accuracy.

Hypothesis
The law of reflection will be correct.

Apparatus and Materials

 Light Box
 Mirror
 Protractor
 Blank Paper

Safety
This experiment is potentially risky. The first risk is that the light box heats up quite a lot and so there is a danger of burning yourself. It also requires a power box, which increases the risk of electrocution, although the risk is small. The second is that this must be done in a dark room which is precautions are not taken, could be dangerous due to the lack of vision.

Method
Independent Variable: Angle of Incidence
Dependant Variable: Angle of Reflection
Controlled Variables: Mirror location, amount of light

1. Set up light box so that one slit of light escapes from the box. (The light box must be plugged into the power box, which must be plugged into the power socket)
2. Set the protractor with the flat edge against the mirror.
3. Aim the light beam at different intervals on the protractor.
4. Measure the angle of reflection.

Results

No. Angle of Incidence Angle of Reflection
1 20o 20o
2 30o 30o
3 40o 40o
4 50o 50o
5 60o 60o

Discussion
The angle of reflection is clearly the same as the angle of incidence. This result occurred in every instance.
By definition, the angle of reflection should equal the angle of incidence, as it is a reflection-a reversed copy-of the original angle. Therefore, logically the reflected light should be identical, simply travelling in the reversed direction.

Evaluation
I think that the data collected is fairly reliable. It could be questioned as the experiment was only repeated once and it was done fairly hastily.