Chapter 8time“Precise Measurement of Time” :
Chapter 8time“Precise Measurement of Time”
Slide 3:
Errors from keeping time by the Earth.
All of the ordinary ways for measuring time based on motions of the earth. This is satisfactory for most purposes because the earth is fairly dependable in its rotation and revolution around the sun. However, scientist who must measure time with very great accuracy find that the earth’s movement is not dependable enough.
The main difficulty is in determining the exact position of the earth relative to the fixed position of the stars. The earth also varies slightly in the rate at which it spins on its axis.
Slide 4:
In every 1000 years, the planet seems to take about 3 ½ seconds longer to make a complete rotation. The earth appears to be slowing down unevenly so that it rotates at different rates from time to time. Slow movements of the earth’s core may also affect its rotation.
Atomic clocks. :
Atomic clocks. The basic requirement for a very accurate clock is a movement or process that is repeated endlessly with absolute regularity. A clock with a swinging pendulum illustrates the measurement of time by means of some sort of constant rhythm.
Scientist have discovered that tiny vibrations are produced by atoms and molecules. All atoms or molecules of the same kind vibrate with an absolutely constant frequency at a given temperature. This natural property of atoms and molecules can be used to control a clock that is completely independent of the motions of the earth.
Slide 6:
Some atomic clocks have an error of one second in 300 years. There seems to be no reason why greater accuracy cannot be achieved. Such super accurate clocks are among the tools needed by scientist in their effort to bring meaning to the world of atomic structure.
Prepared by: Jaymica V. LleraI-DARWIN :
Prepared by: Jaymica V. LleraI-DARWIN
Slide 8:
THANKYOU!!!!
GOD SPEED!!!
GOD BLESS YOU ALL!!!
Submitted To: :
Submitted To: Mrs. Winda D. Obedencio