Physics: “Short Time Intervals” 1960 PSSC Physical Science Study Committee; MIT04:33

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Published on October 8, 2017

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How scientists measure very short time intervals. Timing of lightning is used as an example. Timing equipment including moving cameras, pen recorders and the oscilloscope are shown and explained. Your instructor is Professor Campbell L. Searle of the Massachusetts Institute of Technology (MIT).

Public domain film slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

The second (symbol: s) (abbreviated s or sec) is the base unit of time in the International System of Units (SI).[1][2] It is qualitatively defined as the second division of the hour by sixty, the first division by sixty being the minute.[3] It is quantitatively defined in terms of exactly 9,192,631,770 periods of a certain frequency of radiation from the caesium atom: a so-called atomic clock. Seconds may be measured using a mechanical, electric or atomic clock.

SI prefixes are combined with the word second to denote subdivisions of the second, e.g., the millisecond (one thousandth of a second), the microsecond (one millionth of a second), and the nanosecond (one billionth of a second). Though SI prefixes may also be used to form multiples of the second such as kilosecond (one thousand seconds), such units are rarely used in practice. The more common larger non-SI units of time are not formed by powers of ten; instead, the second is multiplied by 60 to form a minute, which is multiplied by 60 to form an hour, which is multiplied by 24 to form a day.

The second is also the base unit of time in other systems of measurement: the centimeter–gram–second, metre–kilogram–second, metre–tonne–second, and foot–pound–second systems of units…

A millisecond (from milli- and second; symbol: ms) is a thousandth (0.001 or 10−3 or 1/1000) of a second.[1]

10 milliseconds (a hundredth of a second) are called a centisecond.

100 milliseconds (one tenth of a second) are called a decisecond.

To help compare orders of magnitude of different times, this page lists times between 10−3 seconds and 100 seconds (1 millisecond and one second)…

A microsecond is an SI unit of time equal to one millionth (0.000001 or 10−6 or 1/1,000,000) of a second. Its symbol is μs. One microsecond is to one second as one second is to 11.574 days.

A microsecond is equal to 1000 nanoseconds or 1/1,000 milliseconds. Because the next SI prefix is 1000 times larger, measurements of 10−5 and 10−4 seconds are typically expressed as tens or hundreds of microseconds. A microsecond of sound signal sample (44.1 kHz, 2 channel, 24 bit, WAV) is typically stored on 4 µm of CD, 2 bits per µs per 4 µm…

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