AQA A-level Physics Uses of waves
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Ultrasound waves are a type of sound wave which have a frequency which is above the range of human hearing. Ultrasound waves have a number of uses such as a range of uses in medicine and to clean jewellery.
High frequency sound waves are used to detect objects in deep water using the same method as the ultrasound imaging. This is often called SONAR (Sound Navigation and Ranging) and uses waves that are within normal hearing range rather than using ultrasound. They can be manufactured and can be found in the natural world used by some animals, such as bats and dolphins.
Transverse waves such as light are able to be polarised. A light beam is made up of many different waves which are oscillating at random angles; when this is polarised all waves that aren’t oscillating in a certain direction are not allowed through a filter and therefore all waves in the resulting wave are oscillating in the same direction.
Polarisation filters allow light to pass through but only where the waves oscillate in ONE specific direction. For example, if an unpolarised light beam is sent through a filter then the resulting beam of light is vertically polarised. Multiple polarisation filters can be used together, and they can have different effects on the resulting light beam depending on how the filters are rotated.
Loudspeakers use the motor effect to convert electrical signals into sound waves. Variations in the electrical signals create variations in the magnetic field created by the electromagnet in the loudspeaker. This causes the speakers cone to move in and out which creates pressure variations in the air around the speaker, creating sound waves.
Optical fibres use total internal reflection to carry information digitally using light waves. Optical fibre cables can be moved and bent, as long as the critical angle is achieved, and light can still travel down the cable. Uses of fibre optics include phone lines and endoscopies in medicine.
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