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Unformatted text preview: per unit length (1)
Hard magnetic shell (2)
Soft magnet core (3)
Directions of magnetisation (4) Fig. 11.2.9: Wiegand sensor 174 © Festo Didactic GmbH & Co. KG • FP 1110 11. Physical fundamentals 11.3
Sound frequency which is above the limit of human hearing is described as
Fundamentals of ultrasonic- ultrasound. The lower limit is at approximately 20 kHz. The particular characteristics
of ultrasound applied to proximity sensors are the result of the high frequency and
the correspondingly short wavelength. 10 1
Infra (1) 100 1k 10 k 2
Audible (2) 100 k 1M 10 M 100 M 1G 3
Ultra (3) (Hz) 4
Hypersound (4) Fig. 11.3.1: Sound frequency range The propagation of sound is the result of propagation of mechanical long waves,
which manifests itself in a periodic density variation in the carrier medium, leading
to alternating compressions and dilutions. The propagation of sound waves is
dependent on a transmitting medium, it is not possible in a vacuum. Speed of sound in
solid objects For solid objects, t...
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This note was uploaded on 11/01/2012 for the course CHEMICAL 102 taught by Professor Jamesrodriguez during the Spring '12 term at Universidad Politécnica de Cartagena.
- Spring '12