Key Terms
Wavelength
Distance between one peak and the next peak of a wave.
Amplitude
Height of a peak (or depth of a trough). Frequency: rate of vibration; number of wavelengths per unit time.
Reflection
Wave bounces off a material. Absorption (absorbance): material captures the energy of the wave.
Transparency
Allows high proportion of light to pass through. Opacity: blocks light; light is not transmitted.
Interference
Light waves interact with each other, creating complex patterns. Two pebbles in a puddle = same principle.
Diffraction
Light bends or scatters around small objects or openings. Diffraction is greater when the object is smaller relative to
Refraction
Light waves change direction when entering a new medium. Occurs because different materials transmit light at different
Refractive index
Measure of how much a material slows light relative to empty space. Higher refractive index = light slows more = more be
Lens
Object with a curved surface that refracts light so it all meets at a single point called the image point (focus). Focal
Convex lens
Focuses light toward a point on the far side; used to magnify because it focuses at closer range than the human eye. Con
Image manipulation factors
Distance between object and lens, distance between lens and screen, and curvature of the lens. More curvature = focal po
Electromagnetic radiation (EMR)
Energy that includes visible light, microwaves, X-rays, radio waves, and more. Defined by wavelength and frequency.
Dispersion
Separation of white light into component colors by refraction. Occurs because refractive index differs by frequency for
Fluorescence
A chromophore absorbs short-wavelength (high-energy) light and emits longer-wavelength (lower-energy) visible light almo
Phosphorescence
Same concept as fluorescence, but photons are emitted after a delay. Glow-in-the-dark plastics work this way.