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Fundamental Units

Physics: IB Diploma Higher Level, topic 6.1.1

Fundamental Units

Fundamental (or SI base) units are the standard units used to describe physical quantities in physics. They are:

Metre (m)

Metre (m)

  • The SI unit for distance (length).
Kilogram (kg)

Kilogram (kg)

  • The SI unit for mass.
Second (s)

Second (s)

  • The SI unit for time.
Ampere (A)

Ampere (A)

  • The SI unit for electric current.
Kelvin (K)

Kelvin (K)

  • The SI unit for temperature.
Mole (mol)

Mole (mol)

  • The SI unit for chemical mass.
Candela (cd)

Candela (cd)

  • The SI unit for luminous intensity.

Combining SI Units

SI base units can be combined to form lots of other useful SI units:

Hertz (Hz)

Hertz (Hz)

  • The SI unit for frequency.
Newton (N)

Newton (N)

  • The SI unit for force.
Joule (J)

Joule (J)

  • The SI unit for energy.
Watt (W)

Watt (W)

  • The SI unit for power.
Pascal (Pa)

Pascal (Pa)

  • The SI unit for pressure.
Coulomb (C)

Coulomb (C)

  • The SI unit for electric charge.
Volt (V)

Volt (V)

  • The SI unit for electric potential difference.
Ohm (Ω.)

Ohm (Ω.)

  • The SI unit for electrical resistance.
Tesla (T)

Tesla (T)

  • The SI unit for magnetic flux density.

Celsius (°C)

  • Degrees Celsius are derived from the base SI unit for temperature (Kelvin).
  • To convert between Kelvin and °C use the following equation:
  • °C = K - 273.

Test yourself on Fundamental Units

  • Which of these is the SI unit for time?

  • Which of these are SI base units?

  • Which of the following are SI base units?

  • What is the SI unit for frequency?

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