Waves

• Amplitude is the maximum displacement of a wave from its equilibrium position.
• Angles in degrees, Frequency in Hz, Distance in Metres, Velocity of a wave in m/s, Time in seconds
• Wave speed = frequency x wavelength
• The amplitude of a transverse wave is measured by measuring the distance between the crest or trough to the equilibrium line.
• Wavefront is where all the vibrations are in phase and the same distance from a source.
• Wavelength is the distance between a particular point on one cycle of the wave and the same point on the next cycle
• Frequency is the number of waves passing a particular point per second. Is measured in Hertz
• Time period is the time it takes for one complete wave to pass a particular point.
• Waves transfer energy and information but don't transfer matter.
• Frequency = 1/T (time)
• The speed of an EM wave in a vacuum is 300,000,000 m/s
• The speed of a sound wave in air is 340 m/s and doesn't travel in a vacuum.
• Electromagnetic (EM) waves transfer energy, are transverse waves, travel at the speed of light in a vacuum, and can be reflected and refracted.
• What is the order of the electromagnetic spectrum in terms of decreasing wavelength and increasing frequency:

  RadioWaves, Microwaves, Infrared, Visible Light (ROYGBIV), Ultraviolet, X-rays, Gamma.
• ROYGBIV stands for red, orange, yellow, green, blue, indigo and violet.
• The frequency range for human hearing is 20–20,000 Hz
• Uses of each part of the electromagnetic radiation:

  •radio waves: communication

  •microwaves: cooking and communication

  •infrared: heaters and night vision equipment

  •visible light: optical fibres and photography

  •ultraviolet: fluorescent lamps

  •x-rays: observing the internal structure of objects and materials, including for medical applications.

  •gamma rays: sterilising food and sterilising medical equipment.
• The potential dangers of EM waves:

  •microwaves: internal heating of body tissue

  •infrared: skin burns

  •ultraviolet: damage to surface cells and blindness

  •gamma rays: cancer, mutation of cells.