In astrophysics and quantum physics, a jiffy is defined as the time taken for light to travel a distance of one fermi (10^-15 m).
Therefore, a jiffy is about 3 × 10^−24 seconds.
Also, jiffy is used in electronics in which it is the period of an alternating current power cycle.
In UK power supplies, a jiffy is 1/50 of a second while it is 1/60 of a second in North America.
Gilbert Newton Lewis (1875–1946) was the earliest person to define technical usage for jiffy.