How long is a jiffy?

Asked by: Patrick Seymour, Leicester

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.

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.