Quick Navigation

 

Guidelines for Examination

 
 

1.2.2 SI derived units with special names and symbols

Quantity

Unit

Expression

 

Name

Symbol

In other SI units

In terms of SI base units

Plane angle

radian

rad

 

m.m-1

Solid angle

steradian

sr

 

m2.m-2

Frequency

hertz

Hz

 

s-1

Force

newton

N

 

m.kg.s-2

Pressure, stress

pascal

Pa

N.m-2

m-1.kg.s-2

Energy, work; quantity of heat

joule

J

N.m

m2.kg.s-2

Power(1), radiant flux

watt

W

J.s-1

m2.kg.s-3

Quantity of electricity, electric charge

coulomb

C

 

s.A

Electric potential, potential difference, electromotive force

volt

V

W.A-1

m2.kg.s-3.A-1

Electric resistance

ohm

Ω

V.A-1

m2.kg.s-3.A-2

Conductance

siemens

S

A.V-1

m-2.kg-1.s3.A2

Capacitance

farad

F

C.V-1

m-2.kg-1.s4.A2

Magnetic flux

weber

Wb

V.s

m2.kg.s-2.A-1

Magnetic flux density

tesla

T

Wb.m-2

kg.s-2.A-1

Inductance

henry

H

Wb.A-1

m2.kg.s-2.A-2

Luminous flux

lumen

lm

cd.sr

cd

Illuminance

lux

lx

lm.m-2

m-2.cd

Activity (of a radionuclide)

becquerel

Bq

 

s-1

Absorbed dose, specific energy imparted, kerma, absorbed dose index

gray

Gy

J.kg-1

m2.s-2

Dose equivalent

sievert

Sv

J.kg-1

m2.s-2

Catalytic activity

katal

kat

 

mol.s-1

(1)
Special names for the unit of power: the name volt-ampere (symbol 'VA') is used to express the apparent power of alternating electric current, and var (symbol 'var') is used to express reactive electric power. 

Units derived from SI base units may be expressed in terms of the units listed in this annex.

In particular, derived SI units may be expressed by the special names and symbols given in the above table. For example, the SI unit of dynamic viscosity may be expressed as m-1.kg.s-1 or N.s.m-2 or Pa.s.