Figure 1

The Large diffraction grating (Figure 1) has 1600 grooves/mm and is used with a bright light source (arc lamp) to obtain a spectacular continuous spectrum. The first and second order spectra are easily seen, while the third can be seen when the lights in the auditorium are dimmed.

Materials:

1. Large reflective diffraction grating (Figure 1) has 1600 grooves/mm
2. Small reflective diffraction grating
3. 200 small slides with diffraction gratings (536 grooves/mm)
4. Rod base and clamp assembly

Setup/demo:

This highly reflective diffraction grating is secured in a homemade holder with a protective lid and is attached to a Swiss-made survey protractor. Changing the angle of the protractor results in a spectrum shift. Placing a piece of black paper with a slot on the spectrum while shifting it can show to the students how monochromators work.

Figure 2

We also have 200 small slides with diffraction gratings (536 grooves/mm) that can be distributed between students to observe spectra from discharge tubes and other light sources.