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• February 16, 2022

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• PHY101 Physics I © Dr.Cem Özdoğan

• 1-6 Time

• Any standard of time needs to be able to answer:
• When did a thing happen?
• What was its duration?
• Standards of time in the past have included:
• Rotation of Earth
• Quartz vibrations
• Atomic clocks (cesium), with time signals sent out by radio so others can calibrate their clocks. One second is the time taken by 9192631770 oscillations of the light (of a specified wavelength) emitted by a cesium - 133 atom.