| Status: |
STD 2005/06/07 |
| Code: |
192 |
| Symbol: |
s |
| EQ label: |
TIME |
| |
| Quantities associated with this Unit |
|---|
|
| Quantity: |
period duration (period)
|
| Concept definition: |
The duration of one cycle. |
| |
| Reference type: |
PR |
| Reference: |
[ISO 80000-3:2006, item 3-12.a] |
| Supplemental references: |
[ISO 80000-8:2007, item 8-1.a] |
|
| Quantity: |
reverberation time
|
| Concept definition: |
The duration required for the space-averaged sound energy density in an enclosure to decrease to 10-n/10 of its initial value (i.e., by n dB) after the source emission has stopped. |
| |
| Reference type: |
PR |
| Reference: |
[ISO 80000-8:2007, item 8-29.a] |
| Supplemental references: |
|
|
| Quantity: |
time constant (of an exponentially varying quantity)
|
| Concept definition: |
If a quantity is a function of time given by F(t) = A + Be-t/τ, where t is time [ISO 80000-3:2006, item 3-7] and A and B are two constants, then τ is the time constant. |
| |
| Reference type: |
PR |
| Reference: |
[ISO 80000-3:2006, item 3-13.a] |
| Supplemental references: |
|
|
| Quantity: |
half-life
|
| Concept definition: |
The average duration [ISO 80000-3:2006, item 3-7] required for the decay of one half of the atoms or nuclei. |
| |
| Reference type: |
PR |
| Reference: |
[ISO 80000-10:2009, item 10-33.a] |
| Supplemental references: |
|
|
| Quantity: |
reactor time constant
|
| Concept definition: |
The duration [ISO 80000-3:2006, item 3-7] required for the neutron fluence rate [ISO 80000-10:2009, item 10-45] in a reactor to change by the factor e when the fluence rate is rising or falling exponentially. |
| |
| Reference type: |
PR |
| Reference: |
[ISO 80000-10:2009, item 10-82.a] |
| Supplemental references: |
|
|
| Quantity: |
relaxation time
|
| Concept definition: |
The time constant [ISO 80000-3:2006, item 3-13] for exponential decay towards equilibrium. |
| |
| Reference type: |
PR |
| Reference: |
[ISO 80000-12:2009, item 12-33.a and item 12-33.1] |
| Supplemental references: |
|
|
| Quantity: |
carrier lifetime
|
| Concept definition: |
The time constant [ISO 80000-3:2006, item 3-13] for recombination or trapping of minority charge carriers in semiconductors. |
| |
| Reference type: |
PR |
| Reference: |
[ISO 80000-12:2009, item 12-33.a and item 12-33.2] |
| Supplemental references: |
|
|
| Quantity: |
time (duration)
|
| Concept definition: |
The duration of 9 192 631 770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium-133 atom.
SI base unit. |
| |
| Reference type: |
PR |
| Reference: |
[ISO 80000-3:2006, item 3-7.a] |
| Supplemental references: |
[ISO 80000-1:2009, Table 1] |
|
| Quantity: |
mean lifetime (mean life)
|
| Concept definition: |
1/λ, where λ is the decay constant [ISO 80000-10:2009, item 10-26]. |
| |
| Reference type: |
PR |
| Reference: |
[ISO 80000-10:2009, item 10-27.a] |
| Supplemental references: |
|
|
