Optical Radiation - Electromagnetic radiation (light)
that is visible to the human eye.
Orbital Period - The amount of time it takes a
spacecraft or other object to travel once around it's orbit.
Object - Source of diverging light rays;
either luminous or illuminated.
Octave - Interval between two frequencies
with a ratio of two to one.
Ohm - SI unit of resistance; one volt
Ohm’s Law - Resistance of object is constant,
independent of voltage across it.
Opaque - Material that does not transmit
Open-Pipe Resonator - Cylindrical tube with both ends
closed and a sound source at one end.