Radiation Belt - A ring-shaped region around a
planet in which electrically charged particles (usually
electrons and protons) are trapped. The particles follow spiral
trajectories around the direction of the magnetic field of the
planet. The radiation belts surrounding Earth are known as the
Van Allen belts.
Relativistic - Describes anything traveling at
nearly the speed of light, and obeying the special laws of
behavior that apply at such speeds.
RHIC - The Relativistic Heavy Ion
Collider, a physics research machine at Brookhaven National
Laboratory. Will collide two beams of atomic nuclei at 99.95
percent the speed of light.
Radiation - Electromagnetic waves that carry
Radioactive Decay - Spontaneous change of unstable
nuclei into other nuclei.
Radioactive Materials - Materials that undergo
of Projectile - Horizontal distance between
launch point of projectile and where it returns to launch
Ray model of light - Light may be represented by
straight line along direction of motion.
Ray Optics - Study of light using ray model.
Rayleigh Criterion - Two optical images are separable
if central bright spot of one image falls on first dark band of
Real Image - Optical image at which rays from
Receiver - Device that detects
Reference Level - Location at which potential
energy is chosen to be zero.
Reference Point - Zero location in a coordinate
system or frame of reference.
Refraction - Change in direction of light ray
when passing one medium to another.
Refractive Index - Ratio of speed of light in vacuum
to that in the medium.
Resistance - Ratio of potential difference
across device to current through it.
Resistance Force - Force exerted by a machine.
Resistor - Device designed to have a
Responding Variable - Variable that changes as result
of change in manipulated variable.
Rest Energy - Energy due to mass of object; E=
Resultant - Vector sum of two or more
Right-Hand Rules - Used to find force on current or
moving particle in magnetic field; used to find direction of
magnetic field caused by current or of induced EMF.
Rutherford’s Model of Atom - Nuclear model of atom;
essentially all mass in compact, positively- charged object at
center, surrounded by electrons.