A clock is a mechanical or electrical device that measures time and indicates hours, minutes, and sometimes seconds. Ancient clocks were not very accurate, so scientists modified clock mechanisms over time to increase accuracy. There are two main types of clocks based on their display - analog clocks with hands to show hours, minutes, and seconds, and digital clocks that display time numerically. Clocks also differ based on their internal mechanism, with quartz clocks using electronic oscillations controlled by a quartz crystal to be very precise, and atomic clocks being the most accurate as they use periodic vibrations within atoms. Atomic clocks are important for applications like GPS and time distribution services.

3. CLOCKS
What is a Clock?
A clock is a mechanical or
electrical device for measuring
time. It is used to measure time
intervals. It indicates hours,
minutes and sometimes seconds.

4. Many clocks were used
from the ancient time, but
these clocks were not
accurate. So, scientists
modified the clock’s
mechanism to obtain
accuracy.

5. Types of clocks based on display
1. Analog clock
• It has three hands to show the time.
• Hours Hand : It is short and thick. It
shows ‘Hour’
• Minutes Hand: It is long and thin. It
shows ‘Minute’
• Seconds Hand: It is long and very thin.
It shows ‘Second”

6. 2. Digital clocks
•A digital clock displays the time directly.
•It shows the time in numerals or other
symbols.
•It may have a 12 hours or 24 hours
display.

7. Types of clock based on working mechanism
1. Quartz Clock
• These clocks are activated
by ‘electronic oscillations’,
which are controlled by a
‘quartz crystal’.
• The frequency of a vibrating
crystal is very precise.
• The quartz clock is more
accurate than the
mechanical clock.

8. 2. Atomic clock
• Atomic clocks are the most accurate clocks.
• These clocks are making use of periodic vibrations
occurring within the atom.

9. Uses of atomic clocks.
 Atomic clocks are used in Global
Positioning System (GPS)
 Global Navigation Satellite System
(GLONASS)
 International Time Distribution
Services.

10. ASSIGNMENT
•Mention the types of clocks based on the
display.
•How many minutes are there in one hour?
•What type of oscillations are used in quartz
clock?
•Write a short note on different types of clocks.