Current differencing buffered amplifier
Template:TOCright R is the eighteenth letter of the Latin alphabet.
R may also refer to:
Mathematics
- The set of all real numbers, often written as or R
- The Pearson product-moment correlation coefficient r in statistics
Computing
- R (programming language), an environment for statistical computing and graphics
- R (complexity), the set of all recursive languages
- R, RequestBot, a service in QuakeNet's IRC services
- IBM System R, an IBM database system
Engineering
- R-value (insulation), a non-SI measure of thermal resistance used in housing insulation
- R-value (soils), property of soils used in pavement design
- An electronic resistor, e.g. in circuit diagrams
- The R-# refrigerant numbering system
- In fracture mechanics, the ratio between the minimum and maximum stresses
Physics, chemistry and biology
- The spectral resolution in astronomy
- The symbol given to the molar gas constant in chemistry
- A stellar classification for orangish or K carbon stars
- R (cross section ratio), the ratio of hadronic to muonic cross sections
- Röntgen (unit), a unit of measurement for ionizing radiation such as X-ray and gamma rays
- The Rydberg constant, a physical constant relating to energy levels of electrons within atoms
- R, a label that denotes one of two chiral center configurations in the R/S system
- A side chain (an unspecified group of atoms) in a chemical or structural formula
- Arginine, an amino acid
- Relatedness, in biology
- r, representing population growth rate in the r/K selection theory of ecology
- Haplogroup R (mtDNA), a human mitochondrial DNA (mtDNA) haplogroup
- Haplogroup R (Y-DNA), a Y-chromosomal DNA (Y-DNA) haplogroup
- ATC code R Respiratory system, a section of the Anatomical Therapeutic Chemical Classification System
- °R, the symbol for the thermodynamic temperature scale Rankine
Other uses
- R, denoting a member of the Republican Party in American politics
- R, denoting The Crown, Rex (King) or Regina (Queen) in Commonwealth nations
- R. (album) (1998) by R. Kelly
- R (cable operator), a telecommunications company
- A film rating in the Motion Picture Association of America film rating system
- Rated R (Queens of the Stone Age album)
- Rolled R, the alveolar trill of Spanish, Italian, & Arabic languages
- The three Rs of Reading, wRiting and aRithmetic
- In The World Is Not Enough, a character played by John Cleese
- R·Type, an arcade video game
- R: Rock'n Riders, a PlayStation video game
- ®, the registered trademark symbol
- The South African rand currency
- Ryder's NYSE ticker symbol
- R (New York City Subway service)
- R, the military designation for a reconnaissance aircraft.
- Volkswagen Golf R
- In music, abbreviation for ritardando or right (direction)
- R (2010 film), by Danish screenwriter and film director, Tobias Lindholm