# Guidelines for Examination

1.
SI units and their decimal multiples and submultiples
1.1
SI base units
 Quantity Unit Name Symbol Length metre m Mass kilogram kg Time second s Electric current ampere A Thermodynamic temperature kelvin K Amount of substance mole mol Luminous intensity candela cd

Definitions of SI base units:

– Unit of length

The metre is the length of the path travelled in a vacuum by light during 1/299792458 seconds.

– Unit of mass

The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.

– Unit of time

The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.

– Unit of electric current

The ampere is that constant current which if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section and placed one metre apart in a vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per metre of length.

– Unit of thermodynamic temperature

The kelvin, unit of thermodynamic temperature, is the fraction 1/273,16 of the thermodynamic temperature of the triple point of water.

This definition relates to water having the isotopic composition defined by the following amount-of-substance ratios: 0,00015576 mole of 2H per mole of 1H, 0,0003799 mole of 17O per mole of 16O and 0,0020052 mole of 18O per mole of 16O.

– Unit of amount of substance

The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kg of carbon 12. When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles or specified groups of such particles.

– Unit of luminous intensity

The candela is the luminous intensity, in a given direction, of a source that emits monochromatic rays with a frequency of 540 x 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.
1.1.1
Special name and symbol of the SI derived unit of temperature for expressing Celsius temperature
 Quantity Unit Name Symbol Celsius temperature degree Celsius C

Celsius temperature t is defined as the difference t = T-To between the two thermodynamic temperatures T and To where To = 273.15 K. An interval of or difference in temperature may be expressed either in kelvins or in degrees Celsius. The unit of 'degree Celsius' is equal to the unit 'kelvin'.
1.2
SI derived units
1.2.1
Deleted
1.2.2
General rule for SI derived units
Units derived coherently from SI base units are given as algebraic expressions in the form of products of powers of the SI base units with a numerical factor equal to 1.
1.2.3
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.
1.3
Prefixes and their symbols used to designate certain decimal multiples and submultiples
 Factor Prefix Symbol Factor Prefix Symbol 1024 yotta Y 10-1 deci d 1021 zetta Z 10-2 centi c 1018 exa E 10-3 milli m 1015 peta P 10-6 micro μ 1012 tera T 10-9 nano n 109 giga G 10-12 pico p 106 mega M 10-15 femto f 103 kilo k 10-18 atto a 102 hecto h 10-21 zepto z 101 deca da 10-24 yocto y

The names and symbols of the decimal multiples and submultiples of the unit of mass are formed by attaching prefixes to the word 'gram' and their symbols to the symbol 'g'.
Where a derived unit is expressed as a fraction, its decimal multiples and submultiples may be designated by attaching a prefix to units in the numerator or the denominator, or in both these parts.
Compound prefixes, that is to say prefixes formed by the juxtaposition of several of the above prefixes, may not be used.
1.4
Special authorised names and symbols of decimal multiples and submultiples of SI units
 Quantity Unit Name Symbol Value Volume litre l or L(1) 1 l = 1 dm3 = 10-3 m3 Mass tonne t 1 t = 1 Mg = 103 kg Pressure, stress bar bar 1 bar = 105 Pa
(1)
The two symbols 'l' and 'L' may be used for the litre unit.
The prefixes and their symbols listed in F-II, Annex 2, 1.3 may be used in conjunction with the units and symbols contained in this table.