Diffraction Gratings

Wednesday, 3 October 2018

4:49 PM

Untitled picture.png During the lab you are going to read a vernier scale on the spectrometer. You may find these notes on reading vemier scales useful.
The photo above shows the O of the main scale (bottom scale) and the vemier scale (top scale) aligned. You can use this to work out how to read this
vemier scale.

Untitled picture.png The photo above shows the O of the main scale (bottom scale) and the vernier scale (top scale) aligned. You can use this to work out how to read this
vernier scale.
200
What angle in degrees and minutes is shown in the image above?
200

Untitled picture.png During the experiment you will set up the equipment as shown in the diagram.
Right side
'Sp. i ght
position
Collimator
Light Source
Telescope set
to view first

$Untitled picture.png During the experiment you will set up the equipment as shown in the diagram. Right side 'Sp. i ght position Collimator Light Source Telescope set to view first 𝑑﷐sin﷮𝜃﷯=𝑛𝜆 𝑑=﷐𝑛𝜆﷮﷐sin﷮𝜃﷯﷯ Untitled picture.png You will use this to record data similar to that shown in the table below. Complete the table and then use the data in the table to calculate the spacings on the diffraction grating used and the number of slits per millimetre. Wavelength gular position ngular position Angular displacement line spacing order Left (degrees) Right (degrees) (degrees) 2 2 (nm) 589.0 589.6 589.0 589.6 31.69 31.61 19.22 19.21 55.43 55.57 67.92 67.92 11.87 11.98 24.35 24.36 ± 0.000012 The spacing between the lines is 0.002855 The number of lines per mm is 350.3 (mm) 0.002864 0.002840 0.002857 0.002859 on the diffraction grating. Untitled picture.png Light Source Right side •Straight through" position Left side Telescope set to view first You observe the spectrum of a spectral lamp using the spectrometer and a diffraction grating with 600 ± 2 lines per millimeter. You observe the second order (n=2) spectral line of a specific colour, on the left hand side you observe that = 10.4 ± 0.1 0 and then you move the spectrometer to the right hand side and observe the same spectral line (still n=2) at = 94.6 ± 0.1 0. What is the angular displacement for the line? 42.1 Untitled picture.png Machine generated alternative text: no of lines no of lines perman 2 855 7 10 * ) 1472$
$Untitled picture.png Light Source Right side •Straight through" position Left side Telescope set to view first You observe the spectrum of a spectral lamp using the spectrometer and a diffraction grating with 600 ± 2 lines per millimeter. You observe the second order (n=2) spectral line of a specific colour, on the left hand side you observe that = 10.4 ± 0.1 0 and then you move the spectrometer to the right hand side and observe the same spectral line (still n=2) at = 94.6 ± 0.1 0. What is the angular displacement for the line? 42.1 Untitled picture.png What is the uncertainty in the angular displacement? 0.1 What is the wavelength Of the spectral line you have observed? 559 What is the uncertainty in the wavelength? 2.29 Sometimes the 00 reading on the measurement plate is found between and GR. In this case you can not simply find 29 by finding the difference in the angles. Given the identical setup to that described above, but with the measurement plate shifted so that = 313.80 what value will now be measured for BR? 38$

Untitled picture.png What is the uncertainty in the angular displacement?
0.1
What is the wavelength Of the spectral line you have observed?
559
What is the uncertainty in the wavelength?
2.29
Sometimes the 00 reading on the measurement plate is found between and GR. In this case you can not simply find 29 by finding the difference in
the angles. Given the identical setup to that described above, but with the measurement plate shifted so that = 313.80 what value will now be
measured for BR?
38