Question

One second is defined to be equal to:
A. \[1650763.73\] periods of a krypton clock
B. \[652189.63\] period of a krypton clock
C. \[1650755.73\] periods of a cesium clock
D. \[9192631770\] periods of a cesium clock

Answer 1

Hint: You can start by describing the international standard for the value of \[1\] second it is equal to \[9192631770\] period of a cesium clock. For further clarity, you can also explain in brief the process going inside a cesium clock.

Complete answer:
We know that every measurement we make is made about a unit like a length is in meters and volume is in liters, similarly, time is also measured in seconds. For this measurement, the value of \[1\] second of time should always be the same no matter in which country or universe you are measuring it in.
Scientists used various ways to keep the value of \[1\] second constant from using mechanical pendulums to using quartz crystal-based clocks, but all of them would slowly show errors.

To eliminate all such errors in 1967, the international standard for the length of one second came to life. According to this new international standard \[1\] second is equal to \[9192631770\] cycles (or period) of the radiation that gets an atom of Cesium to vibrate between two energy states.

In simple words when exposed to certain frequencies of radiation (usually radio waves) the electrons in an atom will start to jump between energy states. \[1\] second is equal to the time in which the electrons in a cesium atom jump \[9192631770\] times between different energy states when radio waves are used on cesium atoms.
Hence, \[1\] second is equal to \[9192631770\] periods of the cesium clock

So, the correct answer is “Option D”.

Note:
Cesium clocks (or in general atomic clocks) are the most accurate method of keeping track to date. Cesium clocks along with rubidium clocks are used in the Global Positioning System used by militaries and are used as the standard according to which all the different time zones throughout the world are corrected.