Measurement of Time

Time: Time is defined as a limited period between two successive events.

Need to Measure Time: Time plays are important role in our life. In every civilization there has been evidence of people keeping track of time.

In ancient times, people closely followed the movement of the sun, moon and the stars. They noticed that once the sun rose in the morning, it would set after a considerable period. They could do many things from sunrise to sunset. This gave them a concept of ‘time’.

Today, we measure time for a variety of applications. The dictionary defines time as the period between two events. For example, sunrise and sunsets can be taken as two events. Then the period between sunrise and sunset on a particular day would be the ‘time’ between the sunrise and sunset.

Measurement of Time: In the beginning, people used calendars to keep a track of years, which were divided into months and days.

Later, people started keeping track of the time of the day. They started building various instruments to divide the day into smaller parts.

An instrument used to measure time is called a clock.

People used instruments such as sundials and hourglass to keep track of time. The movement of the shadow changed direction with the movement of the sun across the sky, was used to make crude sundials.

An hourglass consisted of two rounded glass bulbs connected by a narrow neck of glass. The top bulb was filled with sand and a measured amount of sand particles streamed down from the top bulb into the bottom bulb, giving the time.

An instrument known as water clock was also used in different parts of the world. It worked on the principle of regulated flow of water.

These devices were not very accurate and there was a need to improve accuracy. A major breakthrough came in 1656, when Christiana Huygens made the first pendulum clock. It consisted of weight and a swinging pendulum.

Another major advancement in timekeeping was the invention of the atomic clock, which is very accurate.

Today, clocks do not just tell us the time of the day; they are also used as timers in ovens, in stopwatches, in various athletic events, etc. the SI unit of time is the seconds.

60 second	1 minute
60 minute	1 hour
24 hours	1 day
3651/4 days	1 year
10 years	1 decade
10 decades	1 century
10 centuries	1 millennium

Sample Questions

(More Questions for each concept available in Login)

Question : 1

A measurement consists of
A. number only
B. unit only
C. Both a and b
D. None of these
Right Option : C
View Explanation

Question : 2

In the S.I. system of units the unit of length is
A. metre
B. kilometre
C. centimetre
D. All of these
Right Option : A
View Explanation

Question : 3

'Light Year' is a unit used to measure which of the following parameters of light ?
A. Distance travelled
B. Velocity
C. Time required
D. Intensity
Right Option : A
View Explanation