PASCO OS-8500 INTRODUCTORY OPTICS SYSTEM - Manual (Page 42)

Introductory Optics System 012-02744K
®
36
Figure 15.2 Measurements with the Diffraction Grating
Data Calculations
Color A L X
1
X
2
λλλλλ
1
λλλλλ
2
Violet
Blue
Green
Yellow
Orange
Red
Table 15.1
Remove the Diffraction Plate and the Slit Mask and replace them with the Diffraction Grat-
ing. Look through the grating and observe the first order spectrum.
➤NOTE: When looking through the Diffraction Grating avert your eye from looking
straight at the filament. Instead, look at a position on the Diffraction Scale about 4 to 5 cm
to the right or left of the slit in the scale.
Using Figure 15.2 to identify the variables, fill in the data in Table 15.1. Review Experiment
9, if necessary, to determine the calculations needed to calculate
λ
1
and
λ
2
, the range of
wavelengths corresponding to each particular color of light.
Compare your results with those of other students, or with textbook values.
➀ Are your results in complete agreement? Can you account for any discrepancies?
➁ What advantages are there in using wavelength rather than color to characterize visible light?
L
X
1
green
(X
2
blue)
1st
maximum
1st
maximum
Zeroth
maximum
violet
blue
green
yellow
orange
red
red
orange
yellow
green
blue
violet
θ
θ
θ
Image on the
Retina of
your eye
Diffraction Grating
red
orange
yellow
green
blue
violet
violet
blue
green
yellow
orange
red
Diffraction
Scale
A
X
2
green
(X
1
yellow)
Slits
x
L
λ = A sin θ = A sin (arctan )
Color Image
seen on
Diffraction Scale
A = Slit spacing = 6000 slits/cm
A = 0.00016cm