attendees some light sources (an image of a star, a flame, some different bulbs or a
TV screen, among others) and we ask them to think what they have in common,
whether they emit light of the same colour and what colour of light would be most
useful for their purpose.
Once we have familiarized the attendees with the light sources and the colour of
the light emitted by each one, we introduce the possibility of “breaking down” the
light into spectra to analyse its chromatic composition. To do so, we show them an
image of a natural rainbow and ask if a similar analysis of artificial light sources
could be done using artificial instruments. After showing them a diffraction grid and
stick it into a spectroscope that they will later mount, we use it to observe the light
spectra of the different artificial sources previously introduced. We asked the
audience about the similarities and differences between the observed spectra.
The assistants observe that there are light sources that have the same spectrum
(the fluorescent light tube, the energy-saving bulb and the mercury Crookes tube)
and associate it with the similarity between the bulbs. The monitor explains that
sources with the same spectrum contain the same gas, in this case mercury. Then, we
try to explain why a substance always emits the same light spectrum. We reflect on
the nature of light and introduce the idea that it is a beam of photons and that changes
in the energy of the atom produce these photons. Therefore, if the changes are
limited (which implies that the energy in the atom is quantized) the light emitted will
always be the same. By reflecting on this explanation, the assistant can explain (in a
non-formal way) how the other sources emit light.
After completing this first part, the attendees move on to the other room where
they will build a spectroscope (Fig. 21.2) with the help of the monitor. The
spectroscope is already printed and die-cast on a cardboard sheet, so not any
additional instruments to assemble it is required. While assembling it, attendees
need to reflect on its structure and determine where the slit, scale and diffraction grid
should be located. As attendees construct the spectroscope, they discuss the usefulness of the spectroscope in everyday life, its scientific usefulness and industrial
applications. Once the spectroscope has been built, we encourage the attendees to
use it to prove it by observing the spectrum of light sources in the room and to
explain them qualitatively using the concepts of electronic states and electronic
transition introduced in the first part of the workshop.
21.5 Conclusions
By using simple instruments and economic materials, we have been able to design
and build a quantitative spectroscope that can be used both in scientific dissemination activities and in the classroom. In fact, the work carried out in the classroom
with the spectroscope shows an increment of the students’ interest in this analysis
method and a better learning of the academic contents. Likewise, its use in the
museum has aroused the general public’s interest in light-emitting processes, their
technological application and their social and economic consequences.
21 Design, Construction and Use of a Quantitative Spectroscope for. . .
269
TV screen, among others) and we ask them to think what they have in common,
whether they emit light of the same colour and what colour of light would be most
useful for their purpose.
Once we have familiarized the attendees with the light sources and the colour of
the light emitted by each one, we introduce the possibility of “breaking down” the
light into spectra to analyse its chromatic composition. To do so, we show them an
image of a natural rainbow and ask if a similar analysis of artificial light sources
could be done using artificial instruments. After showing them a diffraction grid and
stick it into a spectroscope that they will later mount, we use it to observe the light
spectra of the different artificial sources previously introduced. We asked the
audience about the similarities and differences between the observed spectra.
The assistants observe that there are light sources that have the same spectrum
(the fluorescent light tube, the energy-saving bulb and the mercury Crookes tube)
and associate it with the similarity between the bulbs. The monitor explains that
sources with the same spectrum contain the same gas, in this case mercury. Then, we
try to explain why a substance always emits the same light spectrum. We reflect on
the nature of light and introduce the idea that it is a beam of photons and that changes
in the energy of the atom produce these photons. Therefore, if the changes are
limited (which implies that the energy in the atom is quantized) the light emitted will
always be the same. By reflecting on this explanation, the assistant can explain (in a
non-formal way) how the other sources emit light.
After completing this first part, the attendees move on to the other room where
they will build a spectroscope (Fig. 21.2) with the help of the monitor. The
spectroscope is already printed and die-cast on a cardboard sheet, so not any
additional instruments to assemble it is required. While assembling it, attendees
need to reflect on its structure and determine where the slit, scale and diffraction grid
should be located. As attendees construct the spectroscope, they discuss the usefulness of the spectroscope in everyday life, its scientific usefulness and industrial
applications. Once the spectroscope has been built, we encourage the attendees to
use it to prove it by observing the spectrum of light sources in the room and to
explain them qualitatively using the concepts of electronic states and electronic
transition introduced in the first part of the workshop.
21.5 Conclusions
By using simple instruments and economic materials, we have been able to design
and build a quantitative spectroscope that can be used both in scientific dissemination activities and in the classroom. In fact, the work carried out in the classroom
with the spectroscope shows an increment of the students’ interest in this analysis
method and a better learning of the academic contents. Likewise, its use in the
museum has aroused the general public’s interest in light-emitting processes, their
technological application and their social and economic consequences.
21 Design, Construction and Use of a Quantitative Spectroscope for. . .
269