A collection of exercises related to the propagation of light, vision, and the behavior of light sources and diffusing objects.
Extract
[...] Sources and Propagation of Light Mechanics: Exercise In a homogeneous medium (where the refractive index is constant) and isotropic (the properties are the same in all directions of space), a light wave (which belongs to the family of electromagnetic waves) propagates in a straight line. Thus, we can eliminate answers a and c. Then, it is a matter of understanding how vision works. To see an object, it must either emit waves towards the eye (like a light bulb), or reflect waves towards the eye (for example, a book). In all cases, it is the arrival of these waves towards the eye (and the retina) that allows vision. The correct answer is therefore the d. [...]
[...] Exercise 22: The mistake comes from the drawing of the light ray, we see here to the surprise of the elephant (and the fact that the ray comes from its eye) that this ray is supposed to schematize the vision of the mouse by the elephant, but a ray goes from the source (or the emitting object) to the eye, so we must change the arrow direction. If we are interested in the vision of the mouse, then this drawing is correct. [...]
