How to Take Reading in Spectrometer Grating

Procedure

Procedure for real lab

The preliminary adjustments of the spectrometer are made. The grating is set for normal incidence. The slit is illuminated by mercury vapour vamp. The telescope is brought in a line with the collimator and the direct prototype of the slit is fabricated to coincide with the vertical cross wire. The readings of one vernier are noted. The vernier table is firmly clamped. At present, the telescope is rotated exactly through 90° and is stock-still in this position. The grating is mounted vertically on the prism tabular array with its ruled surface facing the collimator. The vernier table is released and is slowly rotated till the reflected image coincides with the vertical cross wire. The leveling screws are adapted then that the image is at the centre of the field of view of the telescope. The prism table is fixed and later making fine adjustments with the tangential screw, the readings of the vernier are noted. Now, the bending of incidence is 45°. The vernier table is then released and rotated exactly through 45° in the proper direction so that the surface of the grating becomes normal to the incident light. The vernier table is firmly clamped in this position.

The telescope is so released and is brought to observe the direct paradigm. On the either side of the direct epitome, the diffraction spectra are seen.The telescope is turned slowly towards the left so that the vertical cross wire coincides with the violet lines of the kickoff social club. The readings of the vernier are taken. The vertical cross wire is then fabricated to coincide with the other lines on the left and the vernier readings are taken in each instance. The telescope is then moved to the right and the reading of dissimilar lines is similarly taken. The departure between the readings on the left and right on the aforementioned vernier is determined for each line. The mean value of this difference gives 2θ-twice the angle of diffraction. Thus the angle of diffraction θ for each spectral line is determined. The wavelength of the green line is 546.one x10^-9m. The number of lines per meter (N) of the grating is calculated. Using this value of N, the wavelengths of the other prominent lines in this spectrum are calculated.

Procedure for simulator:

The simulation virtualizes the Mercury spectrum experiment. The user can apply a grating spectrometer to mensurate the wavelengths of Yellow, Green, Violet and Red lines in the visible spectrum of Mercury.

Components

 Spectrometer, Grating and Mercury Vapour Lamp.

Variable Region:

1. Telescope Calibrate Slider : This slider helps the user to change the focus of telescope.
2. Commencement Push : Helps the user to showtime the experiment afterward setting the focus of telescope. The Start Button can be activated only if the focus of the telescope is proper.
3. Light Toggle Button : Helps the user to switch the lamp ON or OFF.
4. Grating Toggle Push button : Helps the user to place or remove the grating.
5. Telescope Angle Slider : This slider helps the user to modify the angle of telescope.
6. Vernier Angle Slider : This slider helps the user to change the angle of the Vernier.
7. Telescope Angle Slider : Helps make infinitesimal changes of the telescope angle.
8. Calibrating Telescope Button : Helps the user to calibrate the telescope after starting the experiment, if needed.
   

Procedure for simulation

 To standardise the grating:

• Turn the telescope to obtain the image of the slit.

• Turn the telescope to both sides to obtain green lines.Note the reading of both the verniers.

• Calculate the departure in the reading to obtain the diffraction angle. And so from the equation, number of lines per unit length of the grating can be calculated.

To calculate the wavelegth of different lines

• Obtain the direct paradigm.

• Telescope is moved to make the cross-wire coincide with each line of the spectrum.

• Note the readings on the verniers and calculate the diffraction angle.

• Then summate the wavelength of each colour.

 Observations and calculations

Standardization of equipment

For green calorie-free, λ = 546.1nm

 Determination of wavelength for prominent lines

 Results

The wavelegth of Yellow I =  .....................nm

The wavelegth of Xanthous II =  .....................nm

The wavelegth of Bluish-green =  .....................nm

The wavelegth of Violet I =  .....................nm

The wavelegth of Violet II =  .....................nm

meyersthictly.blogspot.com

Source: https://vlab.amrita.edu/index.php?sub=1&brch=281&sim=334&cnt=2

Share this post