Diffraction

The purpose of this lab is to determine the distance (d) between grooves on a CD by diffraction.


We first arrange a laser so it shines on the disk and as it hits the grooves on the disk it causes diffraction. We measure the distance of the light difrracted from the middle to the point of first order maxima and the length from the light source to the wall where the light showing.

Since it causes constructive interference at the first maxima we used the formula

d*sin(theta) = m*lambda

and solve for d.

We see that the distance between grooves on a CD is about 1.5 micrometers.



Concave and Convex Mirrors

The pupose for this experiment is to observe the images formed by two different types of mirrors, concave and convex mirros. To analyze the characteristics of the images due to the curvature of the mirror, distance of the object to the mirror and reflected rays.





The first mirror we observed was a convex mirror.


We first placed an object in front of the mirror, the image appeared smaller than the actual object. The image was upright and was located inside the mirror, farther away relative to the distance of the mirror and object.

As the object is moved closer to the mirror, the image gets larger almost to its actual size.

As the object is moved away from the mirror the image gets smaller.



The second mirror was a concave mirror.

We first placed an object in front of the mirror the image appeared larger than the actual object and inverted, this is when the object was located behind the curvature point.

Once the object was moved closer the image was upright.

The image was located relatively closer than the mirror and object.















The magnification of the image is determined by using the lateral magnification:

m = y(i) / y(o) = -s(i) / s(o)

Where y(i) is the height of the image and y(o) is the height of the object.

s(i) is the distance from the mirror to the image and s(o) is the distance from the mirror to the object.



Standing Waves (short lab)

The purpose of this lab is to determine how frequency and wavelength are related.

First, we had two students hold each end of a spring. Then, we had the students create a standing wave by shaking the spring back and forth in the horizontal direction.

We first started with one wavelength and increased it by one for each trial, with a total of four trials. Two other students also time the amount it took for 20 waves and determined the frequency by dividing the total cycles by the amount of time.

This is the frequency that was determined:

Trial 1 : 2.35 Hz

Trial 2 : 2.86 Hz

Trial 3 : 1.67 Hz

After recording the data, it was then graphed and determined a relationship between wavelength and frequency. The wavelength and frequency seem to be inversely proportional to one another.