A clock is a measuring device/instrument. It helps us to measure time. We measure and define what time of the day it is using a clock. There are many types of clocks and watches. The two most commonly used clocks are Analog and Digital.
Analog clock or watch has
- Two moving hands. It has an hour hand and a minute hand. Few clocks also have a slender long hand called the second hand.
- The clock is divided into 60 equal parts or divisions. The minute hand moves across one division in one minute.
- Hours are marked from 1 to 12.
- The small hand is the hour hand and the big hand is the minute hand.
- The face of the clock is called a Dial.
- Using both the big and the little hand, we exactly know what time it is.
What unit of time clock measures?
Clock measures time in hours, minutes and seconds. A day is equal to 24 hours.
1 Day = 24 hours
1 Hour = 60 minutes
1 minute = 60 seconds |
How to read time in an Analog clock?
An Analog clock has 12 numbers, which divide the clock into 12 equal parts. These divisions indicate the hours. Each hour is divided into five subdivisions that amount to a total of 60 (12 x 5 = 60) divisions/parts that indicate the minutes on a clock. The numbers in black are called clock numbers. When the minute hand moves from one clock number to the next, for example, 12 to 1, 1 to 2, 2 to 3 we say five minutes have passed. When the hour hand moves from one clock number to the next, for example, 12 to 1, 1 to 2, 2 to 3 we say 1 hour has passed.
Analog clock is based on the following rules:
- The hour hand is shorter than the minute hand.
- The hour hand makes a full rotation in 12 hours.
- The minute hand completes one full rotation in 60 minutes.
- The hour hand makes two full rotations in a day(i.e. 24 hours).
- An hour hand moves forward one clock number every hour.
- A minute hand moves forward one clock number every 5 minutes. A clock is split up into 12 sections, and each section is worth 5 minutes.
- One complete trip around the clock by the minute hand means that one hour has passed. When you read a clock, you look at the hour hand first, and then you look at the minute hand.
- One complete trip around the clock by the second-hand means that one minute has passed.
How many minutes will the minute hand take to move from clock number 12 to 3?
Answer: 15 minutes
How many hours will the hour hand take to move from 12 to 3?
Answer: 3 hours
Reading a Clock
Let us try to read the time in the clock shown below:
- Locate the hour hand.
Many times, the arrow will not be pointing exactly at the number; in that case, you would look at which number it was at most recently. Here the hour hand is halfway between the 2 and the 3, you would use 2 as the hour number.
- Locate the minute hand.
It points to the minutes that have passed since a new hour began. The new hour begins at clock number 12. Here the minute hand is pointing to clock number 4, that means the number of minutes is 5 times 4, 5 X 4 = 20. You can easily figure this out by multiplying the clock number by 5 or counting the number of marks starting from clock number 12. If you count the marks, the clock number 4 represents the 20th division.
The time is 2 hours and 20 minutes or you can also write it as 2:20.
IMPORTANT: While writing digital time, always represent minutes in two digits after ':' symbol. Example: 3 hours 5 minutes is written as 3:05 and 3 hours 50 minutes as 3:50.
Example 1:
As the hour hand passed clock number 12 therefore hours are read as 12. The minute hand is at 6, and 5 times 6 is 30. Therefore number of minutes is 30.
Time is 12 hours 30 minutes or 12:30.
Example 2:
As the hour hand passed clock number 3 therefore hours are read as 3. The minute hand is at the second mark after clock number 8. Therefore number of minutes is 40(5 × 8) + 2 = 42
The time is 3:42.
Example 3:
The hour hand is at clock number 5 therefore hours are read as 5. The minute hand is at 12(this is the point from where the counter for the new hour begins) therefore the number of minutes is 0.
The time is 5:00.
What is AM and PM?
- AM runs from midnight( 00:00) to 11:59( one minute before noon). 00:00 is the time when the hour and minute hand are at clock number 12, where the new day starts. AM stands for ante meridiem, which means before midday.
- The noontime starts when both hour and minute hands are at clock number 12 and the hour hand has made one full rotation to reach back to clock number 12.
- PM goes from noon (12:00) to 11:59 (one minute before midnight). PM stands for post meridiem, which means after midday.
- A 12-hour clock is a way of dividing the 24 hours of the day into two sections. The two halves are called Ante meridiem(AM) and post meridiem(PM).
- A 24-hour clock tells the time in which the day runs from midnight to midnight and is divided into 24 hours, numbered from 0 to 24. It does not use AM or PM
Let us practice this:
My school starts at 7:30 AM. I go back home at around 3 PM. I go out to play at 5 PM and sleep at night around 9 PM.
Digital Clock
A clock or watch that shows the time using numbers, not hands. It shows time in the format Hours∶Minutes. This can be in both 12 and 24-hour formats. For example, a 12-hour clock will display 10 o'clock night time as 10:00 PM and a 24-hour clock will display time as 22:00.
