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Wave motion
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It is the transfer of energy
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without (net) transfer of material medium
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Types of waves
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Transverse waves: These are waves in which the direction of wave-motion is perpendicular to the direction of vibration of source.
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Examples: Rope waves, all kinds of electromagnetic radiations, water waves, etc.
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longitudinal waves: These are waves in which the direction of wave-motion is parallel to the direction of vibration of source.
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Examples: Sound waves, compressions and rarefactions in a slinky spring, etc.
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Some terminologies related to the study of wave-motion are:
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Crests: They are the high points. For longitudinal waves the term compressions is used.
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Troughs: They are the low points. For longitudinal waves the term rarefactions is used.
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Amplitude (A): It is the MAXIMUM displacement from the central position.
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Wavelength (λ): It is the displacement between two neighbouring crests.
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Frequency (f): It is the number of waves per unit time.
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Unit: Hz
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Period (T): It is the time taken to produce one complete wave.
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Wavefront: It is the imaginary line on a wave that joins all the crests. Wavefronts can be
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circular wavefronts
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plane wavefronts
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Formulae / Relationships
f = 1 / T
v = f λ
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A ripple tank can help us study waves including
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reflection
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refraction
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Remember “SSS” – Shallower Shorter Slower.
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Frequency of a wave cannot change because it depends on source.
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Electromagnetic spectrum
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Different range of wavelength have been given different names, e.g., radio waves, infrared, etc.
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They are all transverse waves.
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They travel at 3,00,000,000 m/s in vacuum.
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They slow down in other mediums.
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They carry no charge.
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Fluorescence: It is the visible light emitted during absorption of Ultraviolet, X-rays or Gamma rays.
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