: a unit of length equal to 10−15 meters : one quadrillionth of a meter
Example Sentences
Recent Examples on the WebThis explains why the proton and neutron have particular sizes to them, where each one has a radius that’s a little smaller than a femtometer. Ethan Siegel, Forbes, 20 Apr. 2021 Finally, the results are in: Hessels and company have pegged the proton’s radius at 0.833 femtometers, give or take 0.01, a measurement exactly consistent with Pohl’s value.Quanta Magazine, 11 Sep. 2019 Pohl and his team were surprised to find a lower value for the radius, pegging it at 0.84 femtometer—well outside the range of potential sizes established by earlier measurements. Dan Falk, Scientific American, 28 Nov. 2019 The result: their measurement of 0.833 femtometers (just under one-trillionth of a meter) agrees with the smaller value from the 2010 study. Jennifer Ouellette, Ars Technica, 5 Sep. 2019