If we use a non-monochromatic light source, by using this last expression we can
determine the position in which we will observe the maximum of intensity for each
wavelength, that is, for each spectral line. Then, we can draw a scale to directly
measure the wavelength of the radiation. In our spectroscope, we have drawn a line
on the right of the slit in the positions shown in Table 21.1 for the seven values of the
wavelength.
When we use the energy-saving bulb as the light source, we obtain the spectrum
shown in Fig. 21.2 and the scale allows us to measure the wavelength of each
spectral line. In Table 21.2, we show the wavelengths measured using the spectroscope for each spectral line of the energy-saving bulb. Some references (Sansonetti
et al. 1996; Kraftmakher 2010, 2012) allow us to obtain the wavelengths emitted by
these bulbs. We observe in Table 21.2 that the measured and the tabulated wavelength are similar, within the limits that can be expected for an inaccurate instrument
like this.
We have also tested the spectroscope with three laser pointers (red, green and
blue) with wavelengths of 635, 532 and 405 nm, respectively. By measuring the
wavelength with the spectroscope, we confirm that the wavelength measured by
using the spectroscope matches the value provided by the laser devices, within the
precision expected.
21.4 Teaching and Learning Sequence Developed
in the Workshop
The teaching and learning sequence (TLS) is carried out with 20 attendees in two
different rooms, each of which has a maximum of 10 attendees. Each group is guided
by a museum monitor. The workshop is developed through an inquiry-based
strategy.
At the very beginning, the TLS sets a problem and involves the attendees in a
research aiming at finding an answer using their own previous knowledge and with
the assistance of the monitor. In our case, the problem is “Which visible light sources
do we currently have? What light do they emit?” After setting the problem, we carry
out some activities to familiarize the attendees with the problem: we show the
Table 21.1 Position where
each spectral line is observed
λ (nm)
400
450
500
550
600
650
700
x (cm)
3,4
3,9
4,3
4,8
5,2
5,7
6,1
Table 21.2 Measured wavelengths for each spectral line of the low-energy bulb and values
tabulated in the literature
Line
Violet
Blue
Green
Orange
Red
λ measured (nm)
400–450
500
550
600
650
λ tabulated (nm)
405 and 436
492
546
577
612
268
F. Savall-Alemany et al.
determine the position in which we will observe the maximum of intensity for each
wavelength, that is, for each spectral line. Then, we can draw a scale to directly
measure the wavelength of the radiation. In our spectroscope, we have drawn a line
on the right of the slit in the positions shown in Table 21.1 for the seven values of the
wavelength.
When we use the energy-saving bulb as the light source, we obtain the spectrum
shown in Fig. 21.2 and the scale allows us to measure the wavelength of each
spectral line. In Table 21.2, we show the wavelengths measured using the spectroscope for each spectral line of the energy-saving bulb. Some references (Sansonetti
et al. 1996; Kraftmakher 2010, 2012) allow us to obtain the wavelengths emitted by
these bulbs. We observe in Table 21.2 that the measured and the tabulated wavelength are similar, within the limits that can be expected for an inaccurate instrument
like this.
We have also tested the spectroscope with three laser pointers (red, green and
blue) with wavelengths of 635, 532 and 405 nm, respectively. By measuring the
wavelength with the spectroscope, we confirm that the wavelength measured by
using the spectroscope matches the value provided by the laser devices, within the
precision expected.
21.4 Teaching and Learning Sequence Developed
in the Workshop
The teaching and learning sequence (TLS) is carried out with 20 attendees in two
different rooms, each of which has a maximum of 10 attendees. Each group is guided
by a museum monitor. The workshop is developed through an inquiry-based
strategy.
At the very beginning, the TLS sets a problem and involves the attendees in a
research aiming at finding an answer using their own previous knowledge and with
the assistance of the monitor. In our case, the problem is “Which visible light sources
do we currently have? What light do they emit?” After setting the problem, we carry
out some activities to familiarize the attendees with the problem: we show the
Table 21.1 Position where
each spectral line is observed
λ (nm)
400
450
500
550
600
650
700
x (cm)
3,4
3,9
4,3
4,8
5,2
5,7
6,1
Table 21.2 Measured wavelengths for each spectral line of the low-energy bulb and values
tabulated in the literature
Line
Violet
Blue
Green
Orange
Red
λ measured (nm)
400–450
500
550
600
650
λ tabulated (nm)
405 and 436
492
546
577
612
268
F. Savall-Alemany et al.