The atomic clock...

The use of clocks is not new us. We have been using them to measure time. The scientists during the last 2 decades have developed an extremely accurate clock known as atomic clock. It is very accurate to one second over a period of 1700, 000 years. It has revolutionized the field of time measurement. The clock measures the vibrations produced by certain atoms. The time is measured by counting he number of oscillations.
Atomic clock w as invented by By Dr. Willard Frank Libby in 1946. He presented the working principle of an atomic clock.

Advantages of atomic clock are.

1. It is not affected by the vagaries of atmosphere
2. It is not affected by the fluctuations in the rotation of earth.