colour spectra 4t eso physics
TRANSCRIPT
COLOURSSPECTRA
PhysicsLevel 4th ESO (10th grade)
Institut La Sénia
Coloured liquids Coloured Lights Optical fiber
Console Visible Spectrophotometer Cuvette
EQUIPMENT
Solutions of water and food colouring
Spectra of coloured liquids
Visible spectrophotometers produce white light which is dispersed to form the visible spectrumThe dispersed light passes through the cuvette where the solution to be measured is placedThe solution absorbs part of the spectrum except its colour. This is called ABSORBANCE and it is measured by the detector
Spectra of coloured liquids
Results for 1-colour solutions
RED SOLUTION absorbs all the spectrum except red
BLUE SOLUTION violet and green slight absorption, blue no absorption
YELLOW SOLUTION yellow, orange and red register the least absorbance
WATER: colourless, no absorption
Results for 2-colour mixtures
We obtain a green colour which is where we see the least absorbance
The result is an orange colour with minor absorption at yellow, orange and red wavelengths
Yellow + blue
Yellow + red
Results for 2-colour mixtures
We obtain kind of a violet solution. The least absorbance is detected both violet and red part of the visible spectrum
Red + Blue
Coloured light collected by the optical fiber and analysed in the spectrophotometer
Spectra of coloured light
The input light is dispersed inside the spectrophotometerThe spectra show the INTENSITY of each colour which is measured by the detector
Spectra of coloured light
Results for 1-colour lightsBLUE LIGHT
RED LIGHT
GREEN LIGHT
Mainly blue intensity and some green
The highest intensity for orange but some blue it is also included
Green is clearly spotted
Results for white light
BICYCLE FRONT LIGHT
MOBILE PHONE FLASH LIGHT
Observing the two lights before getting the spectra: the bicycle light has got an orange tonality and the flash light is bright white
Therefore, we see that the red colour is present in the bike light spectrum and gives this noticed tonality, while the flash light has a high intensity band in blue colour
Results for more-colours light
RED, BLUE AND GREEN LIGHT
RED AND GREEN LIGHT
The two primary light colours together produce yellow and the spectrum shows it
The result is white light. The spectrum shows one band for each colour
THANKS