How long is a jiffy? © iStock

How long is a jiffy?

Whether you're looking at light or electrical current, we'll let you know what it is in a jiffy...

Asked by: Patrick Seymour, Leicester

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For physicists, a jiffy is how long light takes to travel a distance of one femtometre, which is a millionth of a millionth of a millimetre. That means that there are about three hundred thousand billion billion jiffys in a second. A jiffy also has an electrical meaning. It is the length of a single cycle of alternating current. In the UK’s 50Hz system, a jiffy is thus one-fiftieth of a second.


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