Appendix 9

QUANTITY

SYMBOL

SI UNIT

SYMBOL

DERIVATION

acceleration

a

m s -2

–

velocity/time

acceleration due to

g

m s-2

–

velocity/time

gravity

n

amount of substance

mole

mol

mole fraction (n)

used

amplification factor

µ

a ratio

–

–

angle

θpφpα1

–

–

–

– of incidence

i

degree or

°

–

r

radian

– of refraction

degree or

°

–

radian

– Bragg

θ

number

–

–

– critical

с

degree or

°

–

RA

radian

anode slope

ohm

Ω

ДVa/ДVa

resistance

A

m2

l x b

area

metres square

atomic number

Z

a number

–

number of

protons

Avogadro constant

L, NA

number

–

–

breadth

b

metre

m

fundamental unit

capacitance

С

farad

F

charge/p.d.

charge, electric

Q

coulomb

С

current x time

on electron

e

coulomb

С

l.6 x 10-19C

conductance

G

ohm-1

Ω-1

reciprocal of

I

resistance

current, electric

ampere

A

fundamental unit

decay constant

λ

a ratio

–

–

density

ρ

kg m-3

–

m/V

distance along path

s

metre

m

fundamental unit

efficiency

η

a ratio

–

work output/

electrochemical

z

gC-1

work input

–

mass/charge

equivalent

E

V

electromotive force

volt

energy/charge

electron

e

energy

E

joule

J

N m

– kinetic

Ek

joule

J

N m.Ek=Smv2

– potential

Ep

joule

J

N m.Ep=mgh

Faraday constant

F

coulomb mol-1

C mol-1

96 500 С mol-1

field strength,

E

Vm-1

–

potential

gradient:

electric

p.d./dist.

magnetic

H

ampereturns

–

current ×no. of

Ф

Wb

turns

flux, magnetic

weber

e.m.f./rate of

В

Т

change of flux

flux density

tesla

flux/area

focal length

f

metre

M

–

force

F

newton

N

kg m s-2

free energy

∆G

joule

J

frequency

f

hertz

Hz

oscillations/ time

gas constant

r

joule

J

energy

half-life,

t1/2

second

s

fundamental unit

radioactivity

С

JK-1

–

quantity of heat/

heat capacity

∆H

J

temp. rise

heat of reaction

joule

heat energy

heat capacity,

с

J K-1kg-1

–

heat capacity/

specific

q

J

mass

heat, quantity of

joule

energy

height

h

metre

m

fundamental unit

image distance

v

metre

m

fundamental unit

inductance, mutual

M

henry

H

induced

e.m.f./rate of

change of

L

H

current

self

henry

–

intensity of radiation

I

a number

–

–

latent heat

L

joule

J

quantity of heat

–, specific

l

J kg-1

–

quantity of heat

–, molar

Lm

joule mol-1

J

quantity of heat

length

l

metre

m

fundamental unit

magnetizing force

H

ampereturns

–

–

magnetic moment

m

Wb m

–

torque in unit

m

a ratio

magnetic field

magnification, linear

–

–

mass

m

kilogramme

kg

fundamental unit

– number

A

a number

–

number of

neutrons +

(dm3)

protons

molar volume

Vm

–

volume of 1 mole

molar solution

M

a ratio

moles/dm3

moment of force

–

N m

–

force × perp.

N

a number

distance

neutron number

–

number of

n

neutrons

number

–

–

–

– of molecules

N

–

–

–

– of turns on coil

n

a number

–

–

– order of

p

a number

–

–

spectrum

u

m

object distance

metre

fundamental unit

peak current

I0

ampere

A

see current

peak e.m.f.

E0

volt

V

see e.m.f.

period

Т

second

s

fundamental unit

permeability

µ

H m-1

–

henry/metre

– of vacuum

µ0

H m-1

–

–

–, relative

µr

a ratio

–

м = м / м0

permittivity

ε

F m-1

–

farad/metre

– of vacuum

ε0

F m-1

–

farad/metre

–, relative

εr

a ratio

–

еr = е /е0

potential, electric

V

volt

V

energy/charge

potential difference

V

volt

V

energy/charge

power

P

watt

W

J s-1

pressure

p

pascal

Pa

Nm-2: force/area

radius

r

metre

m

fundamental unit

reactance

X

ohm

Ω

E0 /l0

refractive index

n

a ratio

–

–

resistance

R

ohm

Ω

p.d./current

resistivity, electrical

ρ

ohm-metre

resistance x

d

a ratio

length

relative density

–

сsub / сwater

r.m.s. current

Irms

ampere

A

see current

r.m.s. voltage

Vrms

volt

V

see e.m.f.

slit separation

S

metre

m

fundamental unit

tension

Т

newton

N

see force

temperature, Celsius

θ

degree С

°C

from kelvin

temp., interval

θ

degree

° or K

–

temp., absolute

T

kelvin

К

fundamental unit

thickness

d

metre

m

fundamental unit

time

t

second

s

fundamental unit

torque

T

N m

–

see moment

turns ratio

Т

a ratio

–

nsec / nprim