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# 3: Physical Optics

• 3.1: Light as a Wave
Light exhibits wave nature, though it does so in a manner very different from mechanical waves and sound.
• 3.2: Double-Slit Interference
We begin our lengthy exploration of interference effects for light with the simplest of setups.  By allowing a single source of light to be divided into two parts with the use of two thin slits in a screen, we turn one source into two, and the resulting waves can then be made to interfere with each other, resulting in a static pattern.
• 3.3: Diffraction Gratings
If an interference pattern is the result of two slits, what is the effect of adding many more?  We will explore this here.
• 3.4: Single-Slit Diffraction
Experimentation reveals that an interference pattern occurs when light passes through a single slit.  How can interference occur with what appears to be only a single source?  We will answer this question in this section.
• 3.5: Thin Film Interference
Light slows as it goes from vacuum into transparent media, and like all waves, it is partially reflected when changing media.  This can result in yet another interference phenomenon.
• 3.6: Reflection, Refraction, and Dispersion
In this section we explore three phenomena that result from a light wave encountering a boundary between two different media.
• 3.7: Polarization
Transverse waves in three dimensions like light have a degree of freedom related to the plane into which the transverse "displacement" occurs. For light in particular this leads to interesting phenomena.