Question

One second is equal to

• A. $1650763.73$ time periods of $\text{Kr}$ clock.
• B. $652189.63$ time periods of $\text{Kr}$ clock.
• C. $1650763.73$ time periods of $\text{Cs}$ clock.
• D. $9192631770$ time periods of $\text{Cs}$ clock.

Answer 1

The correct option is D $9192631770$ time periods of $\text{Cs}$ clock.

One second is the time that elapses during $9192631770(9.192631770\times {10}^9)$ cycles of the radiation produced by the transition between two levels of the cesium $133$ atom.