Introduction
The purpose of this lab experiment is to investigate the laws of reflection and refraction. Determine the relationship between: distance of an object in front and the distance of the image behind, the angle of incidence and the angle of reflection of different light rays.
Θ1 = Θ2The angle of incidence equals the angle of refraction.
n = c / v The index of refraction, the speed is faster in a vacuum than in a material. n1 sin Θ1 = n2 sin Θ2The rays of light bend when either entering or leaving through water and traveling through the air. When light/rays pass through one material to another with a different n, the light/ray is bent or refracted.
Procedure
The experiment began by using a mirror for reflection. The mirror being used for reflection is clear glass, and refracts the light rays before being reflected. After attaching the mirror to a wooden block, a pin was stuck on the right side in front of the mirror at the angle indicated in the table. The reflected image was then found on the left side. Another pin was then placed to mark the image so that it aligned with the original pin. The angles of both the first and second angles were recorded and change in Θ calculated.
Part B of the experiment involved using a semicircular plastic container filled with water. The container is aligned on the paper protractor to focus on the mark at the center of the flat side of the container. A pin is placed behind the contain similar to the steps in part A. Now looking through the front, the image of the pin aligns with the focus of the protractor. The second is placed between the eye and image. Part C procedure repeats part B using a semicircular block.
Results
The results from the lab were good, the angles were either the same or off by a few degrees. The law of reflection proved to be true for all surfaces. This being the case because regardless of the material, the light/ray will always hit the surface at a specific point followed by a reflection.
calculations
The percentage errors and percentage difference for lens were as follows:
Experiment 1(using Lens) 1
Percentage error=(focal expected-focal theory/focal theory)*100.
In experiment 1(lens 1)={(5.17-4.49)/4.49}*100=15.14%.
Percentage difference=difference between magnifications{M(h’/h)-M(d’/d)/average of Magnifications}*100
M1=1+0.7+0.8+0.9=3.4; M2= 0.57+0.35+0.41+0.28=1.61
3.4-1.61=1.79
(3.4+1.61)/2=2.51; 1.79/2.51*100=71.3%
Lens 2 (using formula from lens 1)
Percentage error
{(9.79-4.49)/4.49}*100=11.18%
Percentage difference
M1=1+0.5+0.6+0.7=2.8; M2= 0.64+0.52+0.48+0.42=2.07
2.8-2.07=0.73
(2.8+2.07)/2=2.435; 0.73/2.435*100=29.9%
Experiment 2 (using mirrors)
Percentage error= (29-16.1)/16.1*100=80.12%
Percentage difference=M1-M2; M1= 1.5+1.2+1+0.9=4.6; M2= 1.27+1.06+0.826+0.806=3.962
4.6-3.962=0.638/4.281*100=14.9%
Standard deviations
The standard deviation for table 5=0.32
The standard deviation for table 4=0.64
The standard deviation for table 3=0.64
The standard deviation for table 2=0.97
The standard deviation for table1=0. 103
Fd from
1/fr=1/fc+1/fd 1/fd=1/d0+1/di
d0=109.5; d1=53
1/fd=1/d0+1/di
1/109.5+1/53=1/0.01896=52.74
1/fr=1/fc+1/fd
1/8.76-1/52.74=1/fc
1/fc=0.09524; fc=1.33
Error Analysis
Uncertainties of this lab included: normal human error using the basic eyeing of the location of the pin and the measuring of the angles with a protractor, resulting in the general error in calculation. It’s also a possibility that a few errors were caused by equipment imperfections, such as warped mirrors or bent pins. Also, some protractors were more accurate and eligible, while others were not.
Conclusion
Cited work
Kingslake, Rudolf, and R B. Johnson. Lens Design Fundamentals. London: Academic, 2010. Print.
