International System of Units (SI) - University of Idaho

International System of Units (SI)

National Institute of Standards and Technology ()

Multiplication Prefix Symbol factor

1018 1015

1012

109

106

103

102 * 101 * 10-1 * 10-2 *

10-3

10-6

10-9

10-12

10-15

10-18

exa

E

peta

P

tera

T

giga

G

mega M

kilo

k

hecto

h

deka

da

deci

d

centi

c

milli

m

micro ?

nano

n

pico

p

femto f

atto

a

* Prefixes of 100, 10, 0.1, and 0.01 are not formal SI units

From: Downs, R.J. 1988. HortScience 23:881-812.

International System of Units (SI)

Seven basic SI units

Physical quantity

Unit Symbol

Length

meter

m

Mass

kilogram

kg

Time

second

s

Electrical current

ampere

A

Thermodynamic temperature kelvin

K

Amount of substance

mole

mol

Luminous intensity

candela

cd

Supplementary SI units

Physical quantity

Plane angle Solid angle

Unit Symbol

radian

rad

steradian sr

From: Downs, R.J. 1988. HortScience 23:881-812.

International System of Units (SI)

Derived SI units with special names

Physical quantity

Absorbed dose Capacitance Conductance Disintegration rate Electrical charge Electrical potential Energy Force Illumination Inductance Luminous flux Magnetic flux Magnetic flux density Pressure Power Resistance Volume

Unit Symbol Derivation

gray

Gy

farad

F

siemens

S

becquerel Bq

coulomb

C

volt

V

joule

J

newton

N

lux

lx

henry

H

lumen

lm

weber

Wb

tesla

T

pascal

Pa

watt

W

ohm

liter

L

J kg-1 A s V-1 A V-1 l s-1 A s W A-1 N m kg m s-2 lm m-2 V s A-1 cd sr V s Wb m-2 N m-2 J s-1 V A-1 dm3

From: Downs, R.J. 1988. HortScience 23:881-812.

International System of Units (SI)

Non-SI units accepted for use with SI

Name

Nautical mile Knot Hectare Millibar Curie Roentgen Ton

Symbol

n m-1 kn ha mbar Ci R t

Value

1852 m 1.852 km h-1 104 m2 102 Pa 37 GBq 2.58 X 10-4 C kg-1 103 kg

From: Downs, R.J. 1988. HortScience 23:881-812.

International System of Units (SI)

Units prohibited by SI rules

Physical quantity

Energy Energy Energy Force Magnetic flux Length Length Length Luminance Conductance Photo flux density

Unit

calorie, gram Btu erg dyne maxwell micron millimicron Angstrom stilb mho Einstein

SI value

4.184 J 1054.35 J 10-7J 10-5 N 10-8 Wb 1 ?m 1 nm 0.1 nm 104 cd m-2 1 S 1 mol

From: Downs, R.J. 1988. HortScience 23:881-812.

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