Question

The working of a caesium atomic clock is based upon measuring second as the time needed for vibrations of the radiation corresponding to the-

1. transition between two hyperfine levels of first excited state and ground state of caesium-133 atom.
2. transition between two hyperfine levels of  second excited state and ground state of caesium-133 atom.
3. transition between two hyperfine levels of ground state of caesium-133 atom.
4. transition between two hyperfine levels of first excited state of caesium-133 atom.
5.

Answer 1

Correct Answer - Option 3 : transition between two hyperfine levels of ground state of caesium-133 atom.

CONCEPT:

• To measure any time, we use the atomic standard of time that is based on periodic vibrations produced in a cesium atom.
• Cesium clock: It is used at the National Physical Laboratory, New Delhi to maintain the Indian standard of time.
• Also called the atomic clock.
• The vibration of the cesium atom regulates the rate of the cesium atomic clock.
• The uncertainty imparted in time realization is ± 1 × 10-15, e., one part in 10​-15.
• Cesium atomic clocks provide very high accuracy.

EXPLANATION:

• The working of a cesium atomic clock is based upon measuring second as the time needed for vibrations( ≈ 91.9 × 10⁸ ) of the radiation corresponding to the transition between two hyperfine levels of the ground state of  caesium-133 atoms.

Hyperfine levels: Broader spectral lines split as a result of interaction between the magnetic moment of electrons and nuclei of an atom. Such phenomenon forms the hyperfine structure and hyperfine l