Waves

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  • Created by: Franny
  • Created on: 18-08-12 22:36

Wave terminology

Amplitude, y: the maximum displacement of a particle from the midpoint of the oscillation, metre (m).

Period, T: the time taken for one complete oscillation, seconds (s).

Frequency, f: the number of oscillations per second, hertz (Hz).

Wave speed, v: the distance travelled by the wave each second, metres per second (m/s).

Wavelength, lambda: the distance between consecutive points at which the oscillations are in phase, metre (m).

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Longitudinal and transverse waves

In a longitudinal wave the particles oscillate back and forth along the line in which the wave progresses.

In a transverse wave the particles oscillate at right angles to the direction of propagation of the wave.

Sound waves are examples of longitudinal waves.

The back and forth motion of air molecules leads to alternate regions of high and low pressure, called compressions and rare fractions respectively.

Examples of transverse waves are waves in stretched strings or wires and the variations of electric and magnetic fields in electromagnetic radiation.

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Electromagnetic waves

Electromagnetic waves differ from othe types if mechanical waves, in that they do not consist of vibrating particles.

These waves do not require a medium through which to trave, as they consist of regularly changing electric and magnetic fields.

All electromagnetic radiation travels in a vacuum with a speed of 300000000 m/s.

All electromagnetic radiation consists of oscillating electric and magnetic fields that are in phase and whose transverse variations lie within phases at right angles to each other.

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Electromagnetic spectrum part 1

Gamma rays wavelength ranges between 10^-16 to 10^-11. Their method of production occurs when excited nuclei falls to lower energy states. Some of their properties and applications are highly penetrating rays. Used in medicine for destroying tumours, diagnostic imaging and sterilising of instruments.

X-rays wavelength ranges between 10^-14 to 10^-10. Their method of production occurs when fast electrons decelerate after striking a target. Some of their properties and applications are similar to gamma ray, but the method of production means that their energy is more controllable. Used in medicine for diagnosis and therapy; in industry for detecting faults in metals and studying crystal structures

Ultraviolet wavelength ranges between 10^-06 to 10^-8. Their method of production is electrons in atoms that were raised to high energy states by heat or by electric fields falling to lover permitted energy levels. They are used in fluorescent lamps and for detecting forged bank notes. Stimulates the production of vitamin D in the skin to cause tanning; makes some materials fluoresce.

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Electromagnetic spectrum part 2

Visible light wavelength ranges between 4 x 10^-7 to 7 x 10^-7. Their method of production is electrons in atoms that were raised to high energy states by heat or by electric fields falling to lover permitted energy levels. Light focused onto the retina of the eye creates a visual image in the brain. Can be detected by chemical changes t photographic film and electrical charges on th CCDs in digital cameras. Essential energy source for plants undergoing photosynthesis.

Infrared wavelength ranges between 10^-7 to 10^-3. Their method of production is electrons in atoms that were raised to high energy states by heat or by electric fields falling to lover permitted energy levels. Radiated by warm bodies used for heating in cooking, and in thermal imaging devices

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Electromagnetic spectrum part 3

Microwave wavelength ranges between 10^-4 to 10^-1. They're produced by high frequency oscillators such as magnetron; background radiation in space. Some of their properties and applications are when energy is transferred to water molecules in food by resonance at microwave frequencies. Used for mobile phone and satellite communications.

Radio wavelength ranges between 10^-3 to 10^5. They are produce by tuned oscillators linked to an Aries. Some of their properties and applications ar when a wide range of frequencies allow many signals to be transmitted. Groups of very large radio-telescopes can detect extremely faint sources in space.

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