$$\require{cancel}$$

# 4: Geometrical Optics

• 4.1: Images
Light waves that are reflected or refracted change direction, which means that the eye that sees them sees them coming from a direction that does not backtrack to the actual source of the light.  Here we explore some basic cases where the location of the apparent source of light differs from the actual location of the source of the light.
• 4.2: Magnification
The position of an image is not the only way that it differs from the object.  In general the size of an image differs from the size of the object.  Magnification (or diminution) can be quantified in two ways, both of which we will explore here.
• 4.3: Spherical Reflectors
We have looked at images that result from flat interfaces between media, but some particularly interesting (and useful) results come from interfaces that are spherical in shape.  Here we examine reflections off such surfaces.
• 4.4: Spherical Refractors
We continue our examination of how spherical interfaces between media results in images, this time via refraction.
• 4.5: Thin Lenses
The most practical application of geometrical optics comes from allowing light waves to pass into and out of a medium with spherical surfaces on both sides.  We will examine the effects that these lenses have on images.
• 4.6: Multiple Optical Devices
Light can be made to pass through or reflect off an optical device after it has already done so with another device.  Here we determine how such complex optical systems (which are the bases of many devices such as telescopes and microscopes) can be analyzed.
• 4.7: Wrap-Up
Here we will summarize geometrical optics, as well as cover some odds-and-ends that didn't fit into the other sections.