Measurement Of Time Intervals
“Time flows uniformly forward” – Sir Issac Newton
“Time is what a clock reads” – Albert Einstein
A clock is used to measure the time interval. An atomic standard of time, is based on the periodic vibration produced in a Cesium atom. Some of the clocks developed later are electric oscillators, electronic oscillators, solar clock, quartz crystal clock, atomic clock, decay of elementary particles, radioactive dating etc. The order of time intervals are tabulated in Table 1.7.
Table 1.7 Order of Time Intervals
| Event | Order of time interval (s) |
|---|---|
| Lifespan of the most unstable particle | \(10^{−24}\) |
| Time taken by light to cross a distance of nucle | \(10^{−22}\) |
| Period of X-rays | \(10^{−19}\) |
| Time period of electron in hydrogen atom | \(10^{−15}\) |
| Period of visible light waves | \(10^{−15}\) |
| Time taken by visible light to cross through a window pane | \(10^{-8}\) |
| Lifetime of an excited state of an atom | \(10^{−8}\) |
| Period of radio waves | \(10^{−6}\) |
| Time period of audible sound waves | \(10^{−3}\) |
| Wink of an eye | \(10^{−1}\) |
| Time interval between two successive heart beats | \(10^0\) |
| Travel time of light from Moon to Earth | \(10^0\) |
| Travel time of light from Sun to Earth | \(10^2\) |
| Halflife time of a free neutron | \(10^3\) |
| Time period of a satellite | \(10^4\) |
| Time period of rotation of Earth around its axis(one day) | \(10^5\) |
| Time period of revolution of Earth around the sun(one year ) | \(10^7\) |
| Average life of a human being | \(10^9\) |
| Age of Egyptian pyramids | \(10^{11}\) |
| Age of Universe | \(10^{17}\) |