Physical quantities and measurements

Frequency

Hertz (Hz) s^-1

Energy and work

Joule (J) m^2k kg s^2

Precision

Reproducibility; close to other values obtained by repeating the determination using the same procedure

Positive zero error (vernier calipers)

Right of main scale

Density

kg m^-3

SI unit of mass

kilogram (kg)

Velocity

m s^-1

Volume

m^3

Acceleration

ms^-2

Electrical resistance

ohm m^2 kg s^-3 A^-2

SI unit of time

second (s)

Deci (d)

10^-1

Centi (c)

10^-2

Mili (m)

10^-3

Micro (u)

10^-6

nano (n)

10^-9

Kilo (k)

10^3

Mega (M)

10^6

Giga (G)

10^9

Physical quantity

A physical property of a body or substance that can be quantified by measurements

SI unit of electric current

Ampere (A)

Error

Anything that causes measurement to differ from true value

More precise instrument

Can measure smaller intervals, values given are likely to be closer together

SI unit of luminous intensity

Candela (cd)

Accuracy

Correctness; close to true value

Quantity of charge

Coulomb (C) sA

derived units

Defined in terms of the seven base quantities via a system of quantity equations

Systematic error

Error that occurs consistently each time measurement is repeated

Random error

Error that occurs inconsistently each time a measurement is repeated

Electric potential difference, electromotive force

Volt (V) m^2 kg s^-3 A^-1

Power

Watt (W) m^2 kg s^-3

Negative zero error (vernier calipers)

Left of main scale

SI unit of length

Metre (m)

SI unit of amount of substance

Mole (mol)

Force

Newton (N) m kg s^-2