EXPERIMENT 12 CD DIFFRACTION

EXPERIMENT 12 CD DIFFRACTION

 

 

 

Introduction: For this experiment we will be investigating the difraction by reflection. this will be done by striking a laser beam in a cd. this cd contains grooves that act as a reflective grating. with this experiment we well be investigating the equation for diffraction. 

 

 

 

Here are some pictures of our set up.

 

brief description we flashed our laser trhough a hole in our paper and then hitting the cd. the laser then was reflected but it was refracted by the groves in the cd. the distance between our two shining points is the distance between our two first ordere maximas.

 

 

in ordere to proceed in fiding the distance betwween each grove we firs require to know the wavelenght of the laser. this lead to another experiment using a diffrating grating. the top of the  picture is the calculation in finding the wavelenght. once we found our wavelenght we then proceed with our calculation in finding the distance between the grooves of the cd.

 

here is the calculation for the uncertainity of the distance between the grooves.

 

pik

 

 

 

 

in conlusion it was found that with the aid of  the grating slit difraction equation we were able to find the distance between each grove. Our final answer for such distance was to be 1565,31 +- 61.19 nano meters This result fell between the manufaturers standard value wich is about 1600 nm. this proves the validitiy of such equation. 

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  Experiment 9

Lenses

 

 

In this experiment we will be investigating the properties of lenses and the lens maker equation.the purpose of this lab is to identify the difference in images when an object is placed in different points from the lenses. here is one of the most useful forms of the lens maker equation

You can see the setup of this experiment in the lab manual.

                                             

                                                  here are some images of the experiment

                                                      

=.-

After proceeding in finding the focus of our lenses, we found this focus to be 5.2 +,- .5cm. here is the table of our measurements after moving our object in different positions from the focus in order to obtain a different image distance and a different image height. 

                                                   

                               As you can see we gave a reasonable error to our measurement

Here is the procedure we fallow when obtaining the magnification of the lensesfor one of the measurements with its proper procedure in obtaining Uncertainty.

 

 

 

 

 

Answers to question 4.

1.- when the object is less than the focus, the image does not appear in the white board it only appears in the lenses. This is due to the fact that the image is virtual. 
                                                  here is a picture of a virtual image

 

 

 

Graph of di(distance of the image) vs do(distance of the object).

do	di
26	6.28
20	7
15.6	7.4
10.4	9.8
7.8	16

 

 

 

 

Here is the graph of the inverse of di and do

 

slope = .9478    y intercept = .18

 

The y intercept represents :1/focal

 

 in overall we observed that the equation of lensmaker is the main ruler when dealing with objects reflected in lenses. We also observed that images height changes whenever we move the position of our object. When we know our focal we are able to know when does an image stops from being real and turns in to virtual and vise versa.