# coulomb per kilogram

##### SI coherent derived unit whose name and symbol includes an SI coherent derived unit with a special name and symbol
Name Symbol Quantity Expressed in terms of SI base units
coulomb per kilogram C/kg exposure
(x- and γ-rays)
kg−1 s A

### Definition

The coulomb per kilogram, symbol C/kg, is the SI coherent derived unit of exposure to x-rays or γ-rays (gamma rays).

One coulomb per kilogram is the amount of ionising radiation exposure that frees one coulomb of electric charge in one kilogram of air.