Final answer:
The observer determines that a tablecloth is blue under white light because the wave model of light explains color perception through wavelength reflection. The particle model offers insight into phenomena like the photoelectric effect but does not easily account for continuous color perception. Both models are necessary for different contexts and scales.
Step-by-step explanation:
Duality of Light
Our scientific understanding of light incorporates two models: the wave model and the particle model. This duality captures different behaviors of light depending on the circumstances.
Wave Model of Light
When a white light is projected onto a tablecloth, an observer can determine that the color of the tablecloth is blue. This judgement is possible because the wave model explains that light is made up of different wavelengths corresponding to different colors. The tablecloth reflects only the blue wavelengths while absorbing others, thus appearing blue to the observer. This is well described by the wave model as it accurately predicts phenomena such as interference, diffraction, and polarization, which are properties of waves.
Particle Model of Light
The particle model of light, on the other hand, is useful in explaining the photoelectric effect. The particle model of light posits that light consists of particles called photons. The photoelectric effect can be demonstrated using a negatively charged electroscope, a zinc plate, and various light sources. If you shine ultraviolet light onto the zinc plate, electrons may be ejected due to the energy carried by photons, demonstrating light's particle properties. However, the particle model does not readily explain the continuous range of color perception the way the wave model does.
Both models are essential and are used complementarily depending on the scale and phenomenon being observed. Ray tracing, for instance, aligns well with the particle model and can predict the images formed by lenses and mirrors, yet it does not suffice to explain color observations.