The Measurement of Very Short Time Intervals
Open Access
- 1 January 1920
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 15 (1), 12-23
- https://doi.org/10.1103/physrev.15.12
Abstract
Measurement of very short time intervals; a partial deflection method.—After briefly reviewing the usual method of determining time intervals of the order of microseconds, the author describes a method in which the potential difference of a condenser after it has been discharged for the interval of time to be measured, is accurately determined by connecting the condenser through a ballistic galvanometer to a known potential difference, which is made nearly the same as that to be measured, so that the small throw observed merely measures the small correction to be applied to the known potential difference to give the unknown. A steady current through a known resistance is used as the source of known potential difference. The arrangement of circuits is described and also a gang switch which simplifies the experimental manipulation and eliminates possible error from absorbed charge in the condenser. The working equation for computing the time interval from the observations shows that the attainable accuracy depends on the accuracy of a resistance, a resistance ratio and a capacity. The method was tested with the aid of a Helmholtz pendulum and it was shown that an interval of 250 microseconds may be measured with such accuracy that the probable error of each observation need not exceed 0.15 per cent. The precision was such as to enable the determination of an overall temperature coefficient of the Helmholtz pendulum and accessories amounting to about 1 microsecond per degree for the interval just mentioned.Keywords
This publication has 3 references indexed in Scilit:
- On Electromagnetic Induction and Relative Motion.—IIPhysical Review B, 1918
- On Ewell's Method of Measuring Single Potential DifferencesPhysical Review B, 1916
- The Reproduction and Measurement of Very Short Intervals of TimePhysical Review B, 1914