Diffraction Grating
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Procedure
- Hover your cursor over the slider handle (1) and use the up and down arrow keys on the keyboard for fine tuning. The text box 2 also can be used for fine adjustment.
- Move the eyepiece in such a way that, the central fringe coincides the central arrow sign. Record the corresponding reading from the text box 2.
- Now mode the eyepiece toward right side and record the readings for first order spectrum in Table 1
- Repeat the same on the left side and record in Table 1
- Estimate the wavelengths of the spectrum using the expression
- Repeat the same for the second-order spectrum and calculate the wavelengths.
- The mercury vapour lamp can be replaced with the sodium vapour lamp using the switch (3)
- Wavelengths of the Mercury spectral lines are 420.6 nm, 447.2 nm, 492.2 nm, 501.6 nm, 587.6 nm, 667.8 nm. For Sodium lamp, wavelengths are 588.995 nm and 589.592 nm. N=5.9x105 lines/m.
