In general, the basic unit of measurement of time is a day. Depending on how short or long a period we want to measure, the unit of measurement can be in seconds, minutes, hours, days, weeks, fortnights, months, and so on.

**Example 1**

1 minute | = | 60 seconds |

1 hour | = | 60 minutes |

1 day | = | 24 hours |

1 week | = | 7 days |

1 fortnight | = | 14 days (= 2 weeks) |

Other larger units of measurement of time include:

1 year | = | 12 months |

1 year | = | 52 weeks |

1 year | = | 26 fortnights |

A smaller unit of measurement of time is millisecond – 100 milliseconds = 1 second, or

1 millisecond = th of a second.

## How do we measure time?

In the olden days, people measured time with sundials. A sundial works on the principle of sun’s position during the day and the shadow cast by the sun on a dial. However these were not reliable on cloudy or rainy days, and mankind evolved to measuring time through watches and clocks.

There are two types of clocks viz. analog and digital. Analog time is shown in the traditional type of clock with a circular face (or now with different shapes for cosmetic appeal), and pointers called hands.

The clock generally has two hands – a smaller hand points to the hour of the time (called the “hour” hand), and larger hand that points to the minute of the time (also called the “minute” hand or the long hand). In some clocks there is a third hand – a thin long one – representing the seconds of the time (also called the “seconds” hand).

The seconds hand moves quickly i.e. it does a full rotation every minute (hence 60 seconds = 1 minute), and the minute hands moves one step up (i.e. increases) with the completion of every minute. Once the minute hand moves 60 steps, it completes an hour, and the hour hand will move one step up. Hence 60 minutes = 1 hour.

Digital time is shown in the newer and more modern clocks. They all have a liquid crystal display (LCD), and show the time in numbers of hours, minutes and seconds (in some cases) after noon or midnight.

Here are some commonly used terms for time:

noon | = | midday, when the sun is directly overhead |

midnight | = | exactly 12 hours before noon, or after noon |

am | = | ante meridian, i.e. before noon |

pm | = | post meridian, i.e. after noon |

o’clock | = | as shown by the clock (of the clock) |

quarter past | = | a quarter of an hour (i.e. 15 minutes) past a particular hour |

quarter to | = | a quarter of an hour (i.e. 15 minutes) before a particular hour |

half past | = | half an hour (i.e. 30 minutes) past a particular hour |

We now look at different aspects of measurement of time: