# C (disambiguation)

C is the third letter in the Latin alphabet.

C may also refer to:

## Technology

• C battery (size)
• C battery (type), grid bias battery for vacuum tube radios
• A battery charger rate or discharge rate equal to the capacity of a battery divided by 1 hour. For example C for a 1600 mAh battery would be 1600 mA (or 1.6 amps). 2C is twice this rate and 1/2C is half the rate.
• C-clamp, a type of fastener
• C band, radio frequency band from 4 GHz to 6 GHz
• C, the standard abbreviation for an electronic capacitor, used e.g. in circuit diagrams

• ¢, cent

## Mathematics

• C, a digit meaning twelve in hexadecimal and other positional numeral systems with a radix of 13 or greater
• C, the constant of integration
• Ⅽ, in Roman numerals, the symbol for 100
• ℂ or $\mathbb{C}$, the set of all complex numbers
• ℭ or $\mathfrak c$, the cardinality of the continuum
• C, the set of continuous functions
• In probability theory, the combination or "choose" function, uses the notations
$C(n,k)$, $C_k^n$, $^nC_k$, $_nC_k$, or ${n \choose k}$.
• c space, the space of all convergent sequences in functional analysis

## People

• C, alias for Mansfield Smith-Cumming (1859–1923), Chief of the SIS, the UK Secret Intelligence Service, also known as MI6
• His successors as Chief of the SIS have since been generally known by his alias, C.
• C., Roman abbreviation for Gaius