California State University, Chico
PHYS 202B
Copy of CSUF 212L - Interference and Diffracঞon
Total Score: _______ / 100 Orlando Orঞz
Learning Objecঞves
Our objecঞve is to pracঞce applying the equaঞon for interference of light by a diffracঞon graঞng. Then, we'll use this
equaঞon to determine the grid spacing of a diffracঞon graঞng with unknown
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Copy of CSUF 212L - Interference and Diffracঞon
Total Score: _______ / 100 Orlando Orঞz
Learning Objecঞves
Our objecঞve is to pracঞce applying the equaঞon for interference of light by a diffracঞon graঞng. Then, we'll use this
equaঞon to determine the grid spacing of a diffracঞon graঞng with unknown grid spacing.
x Overview of the Apparatus
The video below gives an overview of the apparatus we will use to explore wave interference by diffracঞon. Watch
this video to learn about the setup we will use.
Video instance not printed.
x Effect of Slit Spacing on the Diffracঞon Paern
The interface below allows you to select between twelve videos of different physical setups by expanding the video
selecঞon panel located directly above the video navigaঞon panel (click where it says "Diffracঞon Graঞng"). You can
choose one of four diffracঞon graঞngs and one of three wavelengths of light. Each laser is directed through the
diffracঞon graঞng with a given line spacing placed between the laser and a screen. To switch between videos, select a
diffracঞon graঞng and and a wavelength, then click the buon labelled "Go" to launch the new video.
Each full video shows the placement of the diffracঞon graঞng in front of the laser beam. You can skip to near the end
and find a frame where fog has been sprayed to see the diffracted laser beam clearly. You can then use the protractor
tool to measure the angles of the diffracঞon maxima.
Video instance not printed.
One of the diffracঞon graঞngs available is described as 1000 lines/mm. This means that in each mm of distance
on the graঞng, 1000 lines have been etched. For this graঞng what is the distance, d, between adjacent lines?
?
(/player_help)
?
(/player_help)
11/8/2020 Student Response | Pivot Interactives
https://app.pivotinteractives.com/assignments/5fa1a4af4b6df8002300819a/responses 2/11
2.
Score: 5 / 5
1 / 2 submissions remaining
1 m
10-3 m
10-6 m
10-9 m
Submit Answer
Using the green laser, measure the diffracঞon angle for the first maximum for each of the four choices of
diffracঞon graঞng. Fill in the first two columns of the table below with your measurements.
Graঞng
lines/mm variable
Diffracঞon angle
degrees variable
1/d
1/m variable
sin(diff ang
units
1000 32 1000000 0.53
600 17 600000 0.309
300 9 300000 0.156
100 3 100000 0.0523
sin(diff angle) vs 1/d
angle) (units)
0.3
0.4
0.5
1
2
3
4
5
11/8/2020 Student Response | Pivot Interactives
https://app.pivotinteractives.com/assignments/5fa1a4af4b6df8002300819a/responses 3/11
3.
4.
1/d (1/m)
Display Curve Fit Uncertainঞes
sin(diff angle) Curve:
Score: 0 / 10
Score: 5 / 5
1 / 2 submissions remaining
sin(diff a
0.1M 0.2M 0.3M 0.4M 0.5M 0.6M 0.7M
0.1
0.2
y = Ax + B
A : 5.300e - 7 u1 n/ im ts
B : -0.003153 units
RM SE : 0.005008 units
Recall that for diffracঞon graঞngs, the angle for the first maximum (m=1) is given by the equaঞon
. We can divide through by d and write the equaঞon as . Ploমng on the verঞcal axis and
on the horizontal axis will yield a straight line. What is the slope of this line?
dsin(θ) = λ
sin(θ) = λ/d sin(θ)
1/d
The wavelength of the laser used.
The inverse of the wavelength of the laser used.
The number of diffracঞon graঞngs used.
Submit Answer
Using your collected data fill in the columns for and in the table above. Be sure that your calculated
value of 1/d has the correct unit, 1/m.
Now plot on the horizontal axis and on the verঞcal axis. Use the linear regression tool to find the
slope of the line. What does this give for the wavelength of the laser used?
1/d sin(θ)
1/d sin(θ)
The wavelength 5.300e-7 1/
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