The present international standard of time is:
Correct answer: B. 9192631770 vibrations of cesium atom
- A. 1/84,400 of means solar day
- B. 9192631770 vibrations of cesium atom
- C. 1/60th of minute
- D. 1/3156 x 10^7 of a year
Explanation
The present international standard of time, as measured by atomic clocks, is defined by the exact number of vibrations or oscillations of the cesium atom's electrons. It's specifically defined as 9,192,631,770 vibrations of the cesium atom's electrons in a second. This precise measurement forms the basis of the current definition of the second in the International System of Units (SI).
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Physical quantities are expressed with SI base and derived units, while measurement limits are described through accuracy, precision, absolute and percentage error, and significant figures. Dimensional analysis checks equations, derives relationships and detects inconsistent units, but it cannot determine numerical constants or distinguish quantities with identical dimensions.
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