The ampere ( SI unit symbol: A ), often shortened to amp, is the SI unit of electric current ( quantity symbol: I, i ) and is one of the seven SI base units.

The SI unit of charge, the coulomb, " is the quantity of electricity carried in 1 second by a current of 1 ampere ".

In the International System of Units ( SI ), the standard unit of area is the square metre ( written as m < sup > 2 </ sup >), which is the area of a square whose sides are one metre long.

The meter is defined to be a unit of proper length, but the SI definition does not specify the metric tensor to be used in determining it.

The SI unit of measurement of electric current, the ampere, is named after him.

* aw, or attowatt, an SI unit of power

In the International System of Units ( SI ), B is the symbol of the bel, a unit of logarithmic power ratios named after Alexander Graham Bell.

Considerable confusion exists about the meanings of the SI ( or metric ) prefixes used with the unit byte, especially concerning prefixes such as kilo ( k or K ) and mega ( M ) as shown in the chart Prefixes for bit and byte.

( Note that K is the SI unit for temperature ( kelvin ) and should not be confused with k, the SI prefix for kilo.

In scientific contexts the Btu has largely been replaced by the SI unit of energy, the joule, though it may be used as a measure of agricultural energy production ( Btu / kg ).

The candela ( or ; symbol: cd ) is the SI base unit of luminous intensity ; that is, power emitted by a light source in a particular direction, weighted by the luminosity function ( a standardized model of the sensitivity of the human eye to different wavelengths, also known as the luminous efficiency function ).

Although the candela is now defined in terms of the second ( an SI base unit ) and the watt ( a derived SI unit ), the candela remains a base unit of the SI system, by definition.

The units for magnetic flux Φ, which is the integral of magnetic field over an area, are the weber ( Wb ) in the SI and the maxwell ( Mx ) in the cgs system.

While pressure may be measured in any unit of force divided by any unit of area, the SI unit of pressure ( the newton per square metre ) is called the pascal ( Pa ) after the seventeenth-century philosopher and scientist Blaise Pascal.

These other units are called SI derived units, for example, the SI derived unit of area is square metre ( m < sup > 2 </ sup >), and of density is kilograms per cubic metre ( kg / m < sup > 3 </ sup >).

* 1 square kilometre ( U. S. spelling: square kilometer ), symbol km < sup > 2 </ sup >, is an SI unit of surface area.

The International System of Units ( SI ) recognizes pressure as a derived unit with the dimension of force per area and designates the pascal ( Pa ) as its standard unit.

where l is the length of the conductor in SI units of meters, a is the cross-sectional area ( for a round wire a = πr < sup > 2 </ sup > if r is radius ) in units of meters squared, and ρ is the resistivity in units of ohm · meters.

* Pascal, SI unit of pressure, 1 newton acting on an area of 1 square metre

Square kilometre, symbol km < sup > 2 </ sup >, is a decimal multiple of the SI unit of surface area, the square metre, one of the SI derived units.

The unit is based on the candela, the SI unit of luminous intensity, and the square metre, the SI unit of area.

The square metre ( British spelling ) or square meter ( American spelling ) is the SI derived unit of area, with symbol m < sup > 2 </ sup > ( 33A1 in Unicode ).

* Square metre, an SI measure of area

The lux ( symbol: lx ) is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area.

This page is a progressive and labeled list of the SI area orders of magnitude, with certain examples appended to some list objects.

For example, in SI units, a loop of current with current I and area A has magnetic moment I × A ( see below ), but in Gaussian units the magnetic moment is I × A / c.

which ( if the SI units in parentheses are used ) will give the evaporation E < sub > mass </ sub > in units of kg /( m² · s ), kilograms of water evaporated every second for each square meter of area.

where is the spectral irradiance ( or exitance ) of the light ( SI units: W / m < sup > 3 </ sup > = kg /( m · s < sup > 3 </ sup >)); is the radiant flux of the source ( SI unit: watt, W ); is the area over which the radiant flux is integrated ( SI unit: square meter, m < sup > 2 </ sup >); and is the wavelength ( SI unit: meter, m ).

The majority of the clocks are caesium clocks ; the definition of the SI second is written in terms of caesium.

In the IERS numerical standards, the speed of light in a vacuum is defined as c < sub > 0 </ sub > = in a vacuum, in accordance with the SI units.

Neither G nor M < sub >☉</ sub > can be measured to high accuracy in SI units, but the value of their product is known very precisely from observing the relative positions of planets ( Kepler's Third Law expressed in terms of Newtonian gravitation ).

Only the product is required to calculate planetary positions for an ephemeris, which explains why ephemerides are calculated in astronomical units and not in SI units.

To express even smaller angles, standard SI prefixes can be employed ; in particular, the milliarcsecond, abbreviated mas, is used in astronomy.

It is also not consistent with the SI convention that only units named after persons should be capitalized.

Industry practice, more thoroughly documented at Timeline of binary prefixes and continuing today, is to specify hard drives using SI prefixes and symbols in their SI or " decimal " interpretation.

In SI units, the current density is measured in amperes per square metre.

The SI unit for luminance is candela per square metre ( cd / m < sup > 2 </ sup >).

The SI unit for pressure is the pascal ( Pa ), equal to one newton per square metre ( N · m < sup >− 2 </ sup > or kg · m < sup >− 1 </ sup >· s < sup >− 2 </ sup >).

* Pascal ( unit ) ( Pa ), the SI unit of pressure ( equivalent to one newton per square meter )

The SI unit for pressure is the pascal ( Pa ), equal to one newton per square meter ( N / m < sup > 2 </ sup > or kg · m < sup >− 1 </ sup >· s < sup >− 2 </ sup >).

The SI unit of pressure is the pascal ( symbol: Pa ), defined as one newton per square metre.

However, these dimensions have fundamental significance in terms of Planck units ; when expressed in SI units, the gravitational constant is dimensionally and numerically equal to the cube of the Planck length divided by the product of the Planck mass and the square of Planck time.

The name pascal was adopted for the SI unit newton per square metre by the 14th CGPM in 1971.

The candela per square metre ( cd / m < sup > 2 </ sup >) is the derived SI unit of luminance.