1. C1.b Technical English Project:
Clocks
by Vesna Kosovec
C1.b Technical English Project:
I Wonder How It Works!
Lingva-Valjevo

2. What is it and what is it used for?
A clock is an instrument to indicate, keep, and co-ordinate time.
The word clock is derived from the Celtic words clagan and clocca meaning "bell" that suggests that it was the sound of bells.
In general using today a "clock" refers to any device for measuring and displaying the time.

3. A brief history of the development of clocks
The clock is one of the oldest human inventions.
Sundials:
A sundial shows the time by displaying the position of a shadow on a flat surface.
Practical limitations, such as that sundials work only when the Sun shines, and never during the night, encouraged the use of other techniques for measuring and displaying time.

4. Hourglass: Water clocks:
Water clocks, also known as clepsydra, along with the sundials, are possibly the oldest time-measuring instruments.
The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon and in Egypt around the 16th century BC.
The flow of sand in an hourglass can be used to mark passage of time without respect to reference time (time of day, minutes, etc...) and can be useful for measuring duration and/or intervals.

5. Astronomical clocks: Pendulum clock:
For example Wallingford's clock had a large astrolabe-type dial, showing the sun, the moon's age, phase, a star map, and possibly the planets.
It had a wheel of fortune and an indicator of the state of the tide at London Bridge.
Bells rang every hour, the number of strokes indicating the time.
The next development was after 1656 with the invention of the pendulum clock.
Christiaan Huygens is usually credited as the inventor. He determined the mathematical formula that related pendulum length to time (99.38 cm for the one second movement).
The first model clock was built in 1657 in the Hague.

6. Hairspring: Electric clock:
In 1815, Francis Ronalds published the first electric clock powered by dry pile batteries.
Alexander Bain, Scottish clockmaker, patented the electric clock in 1840.
The electric clock's mainspring is wound either with an electric motor or with an electromagnet.
The development of electronics in the 20th century led to clocks with no clockwork parts at all.
In 1675, Huygens and Robert Hooke invented the hairspring, designed to control the oscillating speed of the balance wheel.
This crucial advance finally made pocket watches possible.

7. Quartz clocks: Atomic clocks:
In 1927 the first quartz clock was built by Warren Marrison and J. W. Horton at Bell Telephone Laboratories in Canada.
The National Bureau of Standards based the time standard of the United States on quartz clocks from 1929 to the 1960s, when it changed to atomic clocks.
Today, atomic clocks are the most accurate clocks in existence.
Atomic clocks were first theorized by Lord Kelvin in 1879.
The first accurate atomic clock, was built by Louis Essen in 1955 at the National Physical Laboratory in the UK.

8. How clocks work: https://www.youtube.com/watch?v=C05W6ohoZkw
All modern clocks use oscillation.
Although the methods they use vary, all oscillating clocks, mechanical, digital and atomic, work similarly.
In mechanical clocks, this is either a pendulum or a balance wheel.
In quartz clocks, it is a quartz crystal.
In atomic clocks, it is the vibration of electrons in atoms as they emit microwaves.

9. How a Mechanical Clock Works:
They have two important parts: a mainspring (or weight) and a pendulum.
Mechanical clocks are with a key, and this tightens the mainspring. As the mainspring unwinds, its energy turns gears which cause the hands to move. The pendulum keeps time and ensures that the gears move at the right pace: second by second.
Instead of a mainspring, some mechanical clocks have driving weights that pull the gears at the right pace.

10. How a Quartz Clock Works: How an Atomic Clock Works:
Quartz clocks operate using the mineral quartz inside of a clock.
The mineral quartz is piezoelectric. This means that when a quartz crystal is squeezed, it generates a very small current of electricity. This also means that when electricity is passed through the quartz crystal, it vibrates.
Quartz crystals vibrate exactly 32,768 times each second!
Although their name might sound dangerous, atomic clocks are not radioactive.
Atomic clocks operate by measuring energy particles.
Atoms are always changing their energy state from positive to negative.
An atomic clock measures how many times the atom switches from positive to negative and vice versa and then uses that number to measure the passing of time.

11. Will it be used in the future?
What is special about it?
This is a device that has been used in different ways for thousands of years ago, is still used today, and will be used in the future.
Right now, the best clocks we use for space operations are accurate to about a second over ten million years.
In the future it will probably be all the clocks on-line connected to one central atomic clock.

12. Quiz

13. The word clock is derived from?
a) Latin words b) German words c) Celtic words

14. The word clock is derived from?
a) Latin words b) German words c) Celtic words

15. Hourglass is based on flow of?
a) water b) sand c) mercury

16. Hourglass is based on flow of?
a) water b) sand c) mercury

17. Where did a water clock exist in the 16th century BC?
a) Greece b) Persia c) Babylon d) Egypt

18. Where have water clock existed in the 16th century BC?
a) Greece b) Persia c) Babylon d) Egypt

19. Who is the inventor of the pendulum clock?
a) Huygens b) Newton c) Hooke

20. Who is the inventor of the pendulum clock?
a) Huygens b) Newton c) Hooke

21. Which element does not exist in the pocket watch?
a) gear b) minute hand c) pendulum

22. Which element does not exist in the pocket watch?
a) gear b) minute hand c) pendulum

23. What is giving power to mechanical clock?
a) spring b) batery c) driving weight

24. What is giving power to mechanical clock?
a) spring b) batery c) driving weight

25. Atomic clock operates by measuring?
a) energy particles b) atom mass c) wave length