Metre FAQs:


Q: Is metre defined as the length of the path travelled by light in a vacuum in 1/299 792 458 seconds?

A: Yes.

Q: Was metre redefined in terms of a certain number of wavelengths of a certain emission line of krypton-86?

A: Yes.

Q: Is metre exactly equivalent to 10 000/254 inches and to 10 000/9 144 yards?

A: Yes.

Q: Is metre subject to uncertainties in characterising the medium?

A: Yes, and to various uncertainties of interferometry, and to uncertainties in measuring the frequency of the source.

Q: Is metre about  3 3⁄8 inches longer than a yard, i.e?

A: Yes, about  39 3⁄8 inches.

Q: Is metre defined as the path length travelled by light in a given time and practical laboratory length measurements in metres are determined by counting the number of wavelengths of laser light of one of the standard types that fit into the length?

A: Yes, and converting the selected unit of wavelength to metres.

Q: Is metre usually delineated today in labs as 1579800?

A: Yes.

Q: Is metre the standard spelling of the metric unit for length in nearly all English-speaking nations except the United States?

A: Yes, and Sweden and the Philippines, which use meter.

Q: Was metre originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole?

A: Yes.

Q: Is metre the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second?

A: Yes.

Q: Is metre still kept at the BIPM under the conditions specified in 1889?

A: Yes.

Q: Was metre first measured with an interferometer by Albert A?

A: Yes, Michelson, the inventor of the device and an advocate of using some particular wavelength of light as a standard of length.

Q: Is metre nearly equivalent to 3 feet  3 3⁄8 inches?

A: Yes.