Time Measurement By Periodic Events

Time Measurement is a complicated task and is always a challenge for us, how do we measure a minute, an hour, a day… our ancestors noticed that there were some periodic events that never changed, like the changing of seasons, rising and setting of the sun, etc. These were the first attempts mankind had ever made to measure time, it was pretty simple and the measurements they got were accurate for those times, the first ever device used to measure time in daytime was the sundial.

time measurement

The oldest sundial was found in Egypt dating back to 3500 BC, a sundial has a dial plates with hour lines engraved on it and a gnomon stick which sticks out at an angle, as the sun move in the sky it casts a shadow on the plate and shows the time, but it works only in daytime, so people had to find other ways to measure time at night time. A candle clock was used by ancient Chinese to measure time at night time; a candle with uniform dimension was used to measure time as the rate at which it would burn for every hour was constant, so markings were made for every inch or so to measure time.

Time Measurement Devices

Notice how periodic events like rising and setting of the sun were used for time measurement, now here is an assignment for you, which periodic event would you use to measure a month?

  • a)    Phases of the moon.
  • b)    Movement of stars.
  • c)    Flowing of water.
  • d)    Changing of seasons.

It takes approximately 29.5 day for the moon to change its phase from one full moon to the next so it’s the closest our ancestors could get to measure a month,

Moon Phases

And a year was measured by changing of seasons, it would take exactly one year for monsoon to return so people counted the number of days in one year this way, measurement of a year was very important because we rely on rain for our crops hence knowledge about rain was vital for agriculture.

As technology advanced, we devised more and more sophisticated methods to measure time, a simple pendulum was used, as long as the weight of the bob and the length of the pendulum is unchanged, the pendulum would oscillate at a constant rate.

Time Measurement Devices

What mechanism does your wrist watch use for time measurement? Modern clocks make use of a piezoelectric crystal called quartz, you must have read quartz written on a wall clock while checking time, well this crystal vibrates at a specific frequency when voltage is applied to it, so it is designed in such a way that a frequency of one hertz is obtained from it, this is used to measure time.

In this way periodic events can be used to measure time, here is an assignment for you, what periodic events can you find around you other than the one mentioned in this article to measure time, make a note of them and find a way to measure accurate time using it. This could be helpful for your next science project.

Stay tuned with Byju’s to learn more about time measurement, time and much more.

Practise This Question

Two cars A and B are moving with the same speed v as shown below.

With respect to car A, car B is: