extremely high frequencies
71Microwave cavity — A microwave cavity is a closed metal structure that confines electromagnetic fields in the microwave region of the spectrum. Such cavities act as resonant circuits with extremely low loss at their frequency of operation. Their Q factor may reach… …
72Phonograph — Turntable redirects here. For other uses, see Turntable (disambiguation). Edison cylinder phonograph ca. 1899 …
73Instrument amplifier — This page is about amplifiers for musical instruments. See also instrumentation amplifier, a type of operational amplifier. An instrument amplifier is an electronic amplifier that converts the often barely audible or purely electronic signal from …
74Hearing aid — Behind the ear aid In the ear aid …
75Square Kilometre Array — The Square Kilometre Array (SKA) is a radio telescope in development which will have a total collecting area of approximately one square kilometre. [ [http://www.skatelescope.org/ Square Kilometre Array] website.] It will operate over a wide… …
76List of fictional elements, materials, isotopes and atomic particles — This list contains chemical elements, materials, isotopes or (sub)atomic particle that exist primarily in works of fiction (usually fantasy or science fiction). No actual periodic elements end in ite , though many minerals have names with this… …
77electromechanical transducer — ▪ instrument Introduction any type of device that either converts an electrical signal into sound waves (as in a loudspeaker) or converts a sound wave into an electrical signal (as in the microphone). Many of the transducers used in… …
78Nikola Tesla — Tesla, aged 37, 1893, photo by Sar …
79Audio system measurements — are made for several purposes. Designers take measurements so that they can specify the performance of a piece of equipment. Maintenance engineers make them to ensure equipment is still working to specification, or to ensure that the cumulative… …
80Nova laser — Nova was a high power laser built at the Lawrence Livermore National Laboratory (LLNL) in 1984 which conducted advanced inertial confinement fusion (ICF) experiments until its dismantling in 1999. Nova was the first ICF experiment built with the… …
