Time plays a significant role in human life. If you understand the value of time better, you can gain experience and develop skills over time. Time is related to all that is going on around us, so we often hear about the time dimension, because time is an essential element of life. Time represents special milestones, including birthdays, anniversaries, and the birth of babies, and helps us organize our daily lives and activities, so we can live a more organized and productive life.

Let’s learn what is time, how it is measured, and what are its different units of measurement.

## What is Time?

Time is defined as the continuous sequence of events that take place in apparently irreversible succession from the past, through the present, to the future. Time is used to quantify, measure, or compare the duration of events or the intervals between them, and even, sequence events.

## What is Measurement of Time?

Measurement of time can be defined as a process of identifying the duration passed for an activity to complete or the duration when a change happens e.g. start eating and finish eating, going to school and coming back from school, etc.

The knowledge of measuring time is one of the basic skills you need in everyday life.

You can measure time by using different units like seconds, minutes, hours, days, months, counting, clapping, etc. There are broadly two types of units that people around the world use.

- Non-Standard Units of Measuring Time
- Standard Units of Measuring Time

## Non-Standard Units of Measuring Time

The non-standard units do not have any fixed measurement in numbers. The measurements vary from person to person and object to object. In a non-standard type of measurement of time, different people use different types of scales to measure the time like counting, clapping, etc.

For example, while playing or doing some activity kids mostly use counting as a tool to measure time. This duration may vary from person to person as different people will measure time differently because of their counting speeds.

## Standard Units of Measuring Time

Standard units are predefined and are based on some fixed or standardized. These units do not change from person to person or object to object. Suppose, there are two people recording the time taken to run a distance using stopwatches, they will be recording the same time. Some examples of measurement of time using standard units are seconds, minute, hour, day, month, etc with clocks and calendars.

## What is a Clock?

A clock is a mechanical or electrical/electronic device used to measure and indicate time. The clock divides the interval of a day into $24$ hours, which is further divided into minutes, and minutes further divided into seconds.

- $1$ day – $24$ hours
- $1$ hour – $60$ minutes
- $1$ minute – $60$ seconds

## Measurement of Time Using Clocks

There are two types of clocks used

- Analog Clocks
- Digital Clocks

### Analog Clock or the $12$-Hour Clock

Most wall clocks are analog, meaning that they have moving hands that show you the time. Some analog clocks use Arabic numbers, while others use Roman numerals.

We measure and define what time of the day it is using clocks. A clock in general has $12$ numbers written on it, from $1$ to $12$. It has an hour hand and a minute hand. Some clocks have a third hand as well. It shows time in seconds and is the fastest moving hand. The time is usually based on a $12$-hour clock.

The hour hand, the shorter of the two hands, completes $1$ rotation $\left(360^{\circ} \right)$ in $12$ hours in a normal $12$-hour analog. The minute hand, the longer hand, completes $1$ rotation through $\left(360^{\circ} \right)$ in $60$ minutes.

In analog clocks, time is read in terms of hours and minutes (seconds are rarely used). The smaller hand denotes the hour and the longer hand denotes the minutes. For example, $12:45$ means it is $45$ minutes past $12$ hours. It can be a.m. or p.m. depending upon whether it is day or night.

**Note:**

- a.m. stands for the Latin
*ante meridiem*, translating to ‘before midday’. This is the time before the sun has crossed the meridian. p.m. stands for*post meridiem*or ‘after midday. – after the sun has crossed the meridian. - A.M. and P.M. are the incorrect ways of representing a.m. and p.m. respectively.

When the minute hand (the longer hand) is at $12$, then time is read in terms of hours only based on the position of the hour hand (the shorter hand).

**Examples**

When the minute hand (the longer hand) is pointing at other numbers (other than $12$), then time is read in terms of hours and minutes based on the position of the hour hand (the shorter hand) and the minute hand.

For minute hand, the numbers $1$ to $12$ represent multiples of $5$, i.e., $1$ means $5$ minutes, $2$ means $10$ minutes, $3$ means $15$ minutes and so on.

**Examples**

### Digital Clock the $24$-Hour Clock

A digital wall clock is a wall clock that displays the time digitally, often using numbers to represent the time. The term “digital” refers to the display of the clock but is also often used when talking about electronic devices.

Generally, we use the $12$-hour clock to measure time. But railways, airlines, armed forces, and newspapers use the $24$-hour clock.

On the $24$-hour clock, the hours from midnight to the next midnight are marked $0$ to $24$.

- On a $24$-hour clock, we use $4$ digits.
- The two digits on the right show the minutes past an hour.
- The two digits on the left show the number of hours.

**Examples**

## Conversion Between $12$-Hour and $24$-Hour Time

You can convert the time between these two formats, i.e., from $12$-hour format to $24$-hour format and from $24$-hour format to $12$-hour format. The rules used in the conversion are:

### Rules for converting time on a $24$-hour clock to time on a $12$-hour clock

- We use a.m. if the number of hours is less than $12$. For example: $09:00$ hours becomes $9:00$ a.m.
- If the number of hours is more than $12$ hours, we subtract $12$ from the number of hours and use p.m. For example: $18:00$ hours becomes $6:00$ p.m. $\left(18 – 12 = 6 \right)$, $19:10$ hours becomes $7:10$ p.m. $\left(19 – 12 = 7 \right)$.
- $00:00$ hours or $24:00$ hours is expressed as $12$ midnight. For example, $00:15$ hours is $12:15$ a.m.
- $12:00$ hours is expressed as $12$ noon. For example, $12:45$ is $12:45$ p.m.

### Rules for converting time on a $12$-hour clock time to time on a $24$-hour clock

- If the time is before $1:00$ p.m, we write the same time. For example, $8:10$ a.m. is expressed as $08:10$ hours. $12:45$ p.m.. is expressed as $12:45$ hours.
- If the time is beyond $1:00$ p.m., we add $12$ to the number of hours. For example, $3:20$ p.m.. is expressed as $15:20$ hours $\left(3 + 12 = 15 \right)$.

## Conclusion

Time is used to quantify, measure, or compare the duration of events or the intervals between them, and even, sequence events. There are two types of standards used to represent time – the $12$-hour format which uses the abbreviations a.m. and p.m. to denote before noon and afternoon and the $24$-hour format.

## Practice Problems

- State True or False
- The clocks with dials are called analog clocks
- The clocks with dials are called digital clocks
- The clocks that display time in numbers are called analog clocks
- The clocks that display time in numbers are called digital clocks
- While converting time from $12$-hour format to $24$-hour format, we add $12$
- While converting time from $12$-hour format to $24$-hour format, we subtract $12$
- While converting time from $24$-hour format to $12$-hour format, we add $12$
- While converting time from $24$-hour format to $12$-hour format, we subtract $12$

- Convert the following time to a $24$-hour format
- $6:15$ a.m.
- $4:05$ p.m.
- $9:30$ a.m.
- $1:00$ p.m.
- $12:45$ a.m.
- $11:30$ p.m.
- $10:50$ a.m.
- $4:20$ a.m.
- $10:20$ p.m.
- $5:10$ p.m.

- Convert the following time to a $12$-hour format
- $12:00$
- $23:57$
- $09:29$
- $16:18$
- $05:25$
- $02:05$
- $17:10$

## Recommended Reading

- Associative Property – Meaning & Examples
- Distributive Property – Meaning & Examples
- Commutative Property – Definition & Examples
- Closure Property(Definition & Examples)
- Additive Identity of Decimal Numbers(Definition & Examples)
- Multiplicative Identity of Decimal Numbers(Definition & Examples)
- Natural Numbers – Definition & Properties
- Whole Numbers – Definition & Properties
- What is an Integer – Definition & Properties

## FAQs

### What is time?

Time is defined as the continuous sequence of events that take place in apparently irreversible succession from the past, through the present, to the future. Time is used to quantify, measure, or compare the duration of events or the intervals between them, and even, sequence events.

### What is the measurement of time?

Measurement of time can be defined as a process of identifying the duration passed for an activity to complete or the duration when a change happens e.g. start eating and finish eating, going to school and coming back from school, etc.

### How many types of formats are there to measure time?

There are two types of formats to measure time.

a) $12$-hour format

b) $24$-hour format

### What is the $12$-hour format?

In the $12$-hour format, time is read in terms of hours and minutes (seconds are rarely used). The smaller hand denotes the hour and the longer hand denotes the minutes. For example, $12:45$ means it is $45$ minutes past $12$ hours. It can be a.m. or p.m. depending upon whether it is day or night.

When the minute hand (the longer hand) is at $12$, then time is read in terms of hours only based on the position of the hour hand (the shorter hand).

### What is the $24$-hour format?

On the $24$-hour clock, the hours from midnight to the next midnight are marked $0$ to $24$.

a) On a $24$-hour clock, we use $4$ digits.

b) The two digits on the right show the minutes past an hour.

c) The two digits on the left show the number of hours.

### How to convert from a $12$-hour format to a $24$-hour format?

Rules for converting time on a $24$-hour clock to time on a $12$-hour clock

a) We use a.m. if the number of hours is less than $12$. For example: $09:00$ hours becomes $9:00$ a.m.

b) If the number of hours is more than $12$ hours, we subtract $12$ from the number of hours and use p.m. For example: $18:00$ hours becomes $6:00$ p.m. $\left(18 – 12 = 6 \right)$, $19:10$ hours becomes $7:10$ p.m. $\left(19 – 12 = 7 \right)$.

c) $00:00$ hours or $24:00$ hours is expressed as $12$ midnight. For example, $00:15$ hours is $12:15$ a.m.

d) $12:00$ hours is expressed as $12$ noon. For example, $12:45$ is $12:45$ p.m.

### How to convert from a $24$-hour format to a $12$-hour format?

Rules for converting time on a $12$-hour clock time to time on a $24$-hour clock

a) If the time is before $1:00$ p.m, we write the same time. For example, $8:10$ a.m. is expressed as $08:10$ hours. $12:45$ p.m.. is expressed as $12:45$ hours.

b) If the time is beyond $1:00$ p.m., we add $12$ to the number of hours. For example, $3:20$ p.m.. is expressed as $15:20$ hours $\left(3 + 12 = 15 \right)$.