Have you ever heard someone say I’ll be back in a jiffy, or it will only take a jiffy? We’ve all heard it from time to time, but what is a jiffy? It sounds like it is a piece of confectionery, but people use the word as if it’s a unit of measurement. Well I can tell you that a jiffy is a measure of time. But just how long is a jiffy? Unlike most other measurements of time such as seconds and minutes for example, a jiffy has different measurements depending on its use, just to make it a little confusing.
The first recommended use of jiffy as a unit of time was made by Gilbert Newton Lewis who suggested it be used to measure how long it takes light to travel 1 centimeter. That length of time is 33.3564 picoseconds, which is really really fast. So anyone who says they will take a jiffy in this context is way wrong, and it will not happen. But it has other uses.
What is a Jiffy in electronics? In electronics a jiffy is the measurement between alternating power cycles, which is 1/50 or 1/60 of a second in most mains power supplies. Once again, it’s a very short unit of time, but not as quick as measuring the speed of light. But even electronics can’t be in agreement for the duration of a jiffy.
In electronics a jiffy has a different measure still. It is the duration of one tick of the system timer interrupt, which can vary depending on the hardware platform being used.
In physics a jiffy is measured as the time it takes for light to travel a specified distance, as first suggested by Lewis. In astrophysics it is measured as the time it takes light to travel one fermi, which is the size of one nucleon. One fermi is 10−15 m, so a jiffy is about 3 × 10−24 seconds.
So when you ask yourself, what is a jiffy, you will know that it is a measurement of time, but an inconsistent one at that. It all depends on which field the unit of time is being measured in. But one thing is fr sure, if you want to know how long is a jiffy, regardless of its use it’s a very short length of time.