Marine Chronometer
A marine chronometer is a highly accurate clock used on ships to determine longitude.
Significance: Essential for navigation by providing precise timekeeping despite the ship's motion.
John Harrison built a successful marine chronometer in 1761, which helped solve the problem of accurate longitude measurement at sea.
Quartz Clocks
Quartz clocks use a quartz crystal as a resonator.
Mechanism: An electrical signal is sent to the quartz crystal, causing it to oscillate due to the piezoelectric effect.
Function: The number of oscillations is counted and converted into seconds for display.
Atomic Clocks
Atomic clocks use atoms as resonators and a laser as the power source.
Mechanism: Atoms are excited to a higher energy state by a laser and release radiation as they return to their lower state.
The frequency of this radiation is used to measure time.
Example: Caesium atomic clocks use caesium-133 atoms and measure radiation with a frequency of 9,192,631,770 Hz for one second.
Advancements
Next-generation clocks use optical frequencies (hundreds of terahertz) for even greater accuracy, with research extending into nuclear clocks for potential ultra-high precision.
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