Model 141-WLS – white light source and power pack
White Light Source
An adjustable temperature broad-band white light source for observation and photography of absorption spectra of colored solutions.
Cell Phone Spectral Measurements
Color, Absorption Spectra, and MicroLab’s New White Light Source
Color is what is left over when components of a white light spectrum are selectively removed. Today a continuous spectrum of white light is hard to find in a lab. Overhead lights are fluorescent or LED to save energy, and daylight is not always available.
MicroLab’s patented Model 141 Visual Spectrometer includes a new adjustable-temperature broad-band white light source for observation and photography of absorption spectra of colored solutions. The cooler temperature (black push-button) helps students visualize the effect of change in the Boltzman energy distribution—the loss of high-energy blue light with the decrease in source temperature. The light source is powered by a UL-rated 12VAC wall-mount power block.
White light passing under the sample vial provides a “blank” reference spectrum. The fiber optic can provide another reference or comparison spectrum. All spectra are in wavelength alignment.
Molecular Absorption Spectra and Beer’s Law
The selection of a wavelength for Beer’s Law experiments is counterintuitive. Students find it hard to understand because it is the light that is absorbed that counts, not what comes through the colored sample. Conventional wisdom is to choose green light for a green sample. What is going on here? You have to think about absorbance. This green sample absorbs red and violet light. The red LED spotted below the spectrum with the fiber optic adapter matches the sample absorption and would be a good choice for a Beer’s Law experiment.
Violet would also work.
- Demonstration of absorption bands of colored liquids.
White Light Source
|Light Source||12-watt tungsten desk lamp bulb||Dimensions|
|Power||12 VAC wall-mount 1 amp power pack.|
|Operating temperatures||12 watt, 100% 6 watts, 50%|