1 sec = how many units

You may also want to find out how many days are between two dates on the calendar. Use the date calculator to get your age in days or measure the duration of an event. You can do the reverse unit conversion from ms to sec , or enter any two units below:. The second symbol s is a unit for time, and one of seven SI base units.

It is defined as the duration of 9,,, periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium atom at zero kelvins. Unit of amount of substance. The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6. This number is the fixed numerical value of the Avogadro constant, N A , when expressed in the unit mol -1 and is called the Avogadro number.

The amount of substance, symbol n , of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles. Unit of luminous intensity. The candela, symbol cd, is the SI unit of luminous intensity in a given direction. Necessary cookies enable core functionality such as security, network management, and accessibility.

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The cookies collect information in a way that does not directly identify anyone. The second is used to measure time. As well as enabling us to tell the time of the day, accurate timekeeping is key to satellite navigation systems, underpins the functioning of the internet and facilitates timestamping for transactions in financial trading.

Ancient civilisations used sundials and obelisks to tell the time, which was not very precise, and was restricted in cloudy weather or at night. These methods of timekeeping were based on the daily rotation of the Earth around its own axis.

However this period of rotation is not regular enough to serve as a definition for modern-day applications. Atomic clocks, which keep time using transition energies in atoms, revolutionised timekeeping. NPL developed the first operational caesium-beam atomic clock in This clock was so accurate that it would only gain or lose one second in three hundred years.

Modern atomic clocks can be as much as a million times more accurate than this, and underpin satellite technology, like GPS or the internet. The wording of the definition was updated in Satellite navigation systems determine locations using signals from atomic clocks on board satellites. Accurate timestamping of financial transactions is important to help prevent trading irregularities and to keep an audit trail. Play video.