Which definition of R do you mean?

  • Gas Constant n (physics) the universal constant in the gas equation: pressure times volume = R times temperature; equal to 8.3143 joules per kelvin per mole
  • R n the 18th letter of the Roman alphabet
  • Radius n the length of a line segment between the center and circumference of a circle or sphere
  • Roentgen n a unit of radiation exposure; the dose of ionizing radiation that will produce 1 electrostatic unit of electricity in 1 cc of dry air