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Subject: Music

This US group was formed in Los Angeles, California, in 1978 by Steve Allen (guitar, vocals) and Ron Flynt (bass, vocals), two expatriate musicians from Tulsa, Oklahoma. Drummer Mike Gallo ...

infrasound

infrasound   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
13 words

...infrasound Soundlike waves with frequencies below the audible limit of about 20...

audibility

audibility   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
33 words

...audibility The limits of audibility of the human ear are between about 20 hertz (a low rumble) and 20 000 hertz (a shrill whistle). With increased age the upper limit falls quite...

freezing mixture

freezing mixture   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
25 words

...freezing mixture A mixture of components that produces a low temperature. For example, a mixture of ice and sodium chloride gives a temperature of −20...

cobalt steel

cobalt steel   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
40 words

...cobalt steel Any of a group of alloy steels containing 5–12% of cobalt, 14–20% of tungsten, usually with 4% of chromium and 1–2% of vanadium. They are very hard but somewhat brittle. Their main use is in high-speed...

tennessine

tennessine   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
60 words

...a p -block transactinide element ; a.n. 117; mass number of the most stable isotope 294, with a half-life of about 50 ms (there is one other main isotope). Tennessine was discovered in the first decade of the 21st century in a nuclear reaction between berkelium -249 and calcium-20...

loudspeaker

loudspeaker   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
100 words

... A transducer for converting an electrical signal into an acoustic signal. Usually it is important to preserve as many characteristics of the electrical waveform as possible. The device must be capable of reproducing frequencies in the range 150–8000 hertz for speech and 2020 000 Hz for music. The most common loudspeaker consists of a moving-coil device. In this a cone-shaped diaphragm is attached to a coil of wire and made to vibrate in accordance with the electrical signal by the interaction between the current passing through the coil and a steady magnetic...

speed of sound

speed of sound   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
217 words

...speed of sound Symbol c or c s . The speed at which sound waves are propagated through a material medium. In air at 20°C sound travels at 344 m s −1 , in water at 20°C it travels at 1461 m s −1 , and in steel at 20°C at 5000 m s −1 . The speed of sound in a medium depends on the medium’s modulus of elasticity ( E ) and its density ( ρ ‎) according to the relationship c =√( E / ρ ‎). For longitudinal waves in a narrow solid specimen, E is the Young modulus; for a liquid E is the bulk modulus ( see elastic modulus ); and for a gas E = γ ‎ p ,...

binary prefixes

binary prefixes   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
259 words

...In computing, it became common to use the prefix ‘kilo-’ to mean 2 10 , so one kilobit was 1024 bits (not 1000 bits). This was extended to larger prefixes, so ‘mega-’ in computing is taken to be 2 20 (1 048 576) rather than 10 6 (1 000 000). However, there is a variation in usage depending on the context. In discussing memory capacities megabyte generally means 2 20 bytes, but in disk storage (and data transmission) megabyte is often taken to mean 10 6 bytes. (In some contexts, as in the capacity of a floppy disk, it has even been quoted as 1 024 000 bytes,...

nucleon emission

nucleon emission   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
152 words

...of a nucleon (i.e. a proton or neutron). Proton emitters have fewer neutrons than their stable isotopes. Proton emitters are therefore found below the Segrè plot stability line. For example, 17 Ne (neon–17) has three fewer neutrons than its most abundant stable isotope 20 Ne (neon–20). There are no naturally occurring proton emitters. Neutron emitters have many more neutrons than their stable isotopes. For this reason, emitters may be found above the stability line on the Segrè plot and in most cases can also decay by negative beta decay . There are no...

sound

sound   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
143 words

...sound A vibration in an elastic medium at a frequency and intensity that is capable of being heard by the human ear. The frequency of sounds lie in the range 2020 000 Hz, but the ability to hear sounds in the upper part of the frequency range declines with age ( see also pitch ). Vibrations that have a lower frequency than sound are called infrasounds and those with a higher frequency are called ultrasounds . Sound is propagated through an elastic fluid as a longitudinal sound wave , in which a region of high pressure travels through the fluid at the...

ammonia clock

ammonia clock   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
138 words

...excited ammonia molecules ( see excitation ). The ammonia molecule (NH 3 ) consists of a pyramid with a nitrogen atom at the apex and one hydrogen atom at each corner of the triangular base. When the molecule is excited, once every 20.9 microseconds the nitrogen atom passes through the base and forms a pyramid the other side: 20.9 microseconds later it returns to its original position. This vibration back and forth has a frequency of 23 870 hertz and ammonia gas will only absorb excitation energy at exactly this frequency. By using a crystal oscillator to...

Planck, Max Karl Ernst Ludwig

Planck, Max Karl Ernst Ludwig (1858–1947)   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
80 words

...) German physicist , who became a professor at Berlin University in 1892 . Here he formulated the quantum theory , which had its basis in a paper of 1900 . ( See also Planck constant ; Planck’s radiation law .) One of the most important scientific discoveries of the 20th century, this theory earned him the 1918 Nobel Prize for physics. He also made important contributions to thermodynamics and the special theory of relativity...

noise

noise   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
85 words
Illustration(s):
1

...noise 1. Any undesired sound. It is measured on a decibel scale ranging from the threshold of hearing (0 dB) to the threshold of pain (130 dB). Between these limits a whisper registers about 20 dB, heavy urban traffic about 90 dB, and a heavy hammer on steel plate about 110 dB. A high noise level (industrial or from overamplified music, for example) can cause permanent hearing impairment. 2. Any unwanted disturbance within a useful frequency band in a communication channel. Noise. Decibel scale. ...

Millikan, Robert Andrews

Millikan, Robert Andrews (1868–1953)   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
81 words

...Millikan, Robert Andrews ( 1868–1953 ) US physicist , who after more than 20 years at the University of Chicago went to the California Institute of Technology in 1921 . His best-known work, begun in 1909 , was to determine the charge on the electron in his oil-drop experiment, which led to the award of the 1923 Nobel Prize for physics. He then went on to determine the value of the Planck constant and to do important work on cosmic radiation...

sigma particle

sigma particle   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
113 words

...are Σ ‎ − (dds), Σ ‎ 0 (dus), Σ ‎ + (uus), where d, u, and s denote down, up, and strange, respectively. The masses of the sigma particles are 1189.36 MeV ( Σ ‎ + ), 1192.46 MeV ( Σ ‎ 0 ), 1197.34 MeV ( Σ ‎ − ); their average lifetimes are 0.8×10 −10 s ( Σ ‎ + ), 5.8×10 −20 s ( Σ ‎ 0 ), and 1.5×10 −10 s ( Σ ‎ −...

geocentric universe

geocentric universe   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
89 words

...geocentric universe A view of the universe in which the earth is regarded as being at its centre. Galileo Galilei finally established that the earth revolves round the sun (not the other way round, as the church believed); during the 20th century it became clear from advances in observational astronomy that the earth is no more than one of a number of planets orbiting the sun, which is one of countless millions of similar stars, many of which undoubtedly possess planetary bodies on which life could have...

tomography

tomography   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
87 words

...around the horizontal patient, making numerous X-ray measurements every few degrees. The vast amount of information acquired is built into a three-dimensional image of the tissues under examination by the scanner’s own computer. The patient is exposed to a dose of X-rays only some 20% of that used in a normal diagnostic...

ultrasonics

ultrasonics   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
97 words

...ultrasonics The study and use of pressure waves that have a frequency in excess of 20 000 Hz and are therefore inaudible to the human ear. Ultrasonic generators make use of the piezoelectric effect , ferroelectric materials , or magnetostriction to act as transducers in converting electrical energy into mechanical energy. Ultrasonics are used in medical diagnosis, particularly in conditions such as pregnancy, in which X-rays could have a harmful effect. Ultrasonic techniques are also used industrially to test for flaws in metals, to clean surfaces, to...

flerovium

flerovium   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
85 words

...flerovium Symbol Fl. A radioactive transactinide element ; a.n. 114. It was first made in 1998 at Dubna, Russia, by bombarding plutonium–244 nuclei with calcium–20 nuclei and also occurs from the decay of even heavier elements. About 80 atoms of flerovium have been made. It is thought that the isotope flerovium–298 should be relatively long-lived since both the number of protons (114) and that of neutrons (184) are magic numbers . Flerovium is named after the Russian nuclear physicist Georgy Flerov...

cryogenic pump

cryogenic pump   Quick reference

A Dictionary of Physics (8 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Physics
Length:
71 words

...cryogenic pump A vacuum pump in which pressure is reduced by condensing gases on surfaces maintained at about 20 K by means of liquid hydrogen or at 4 K by means of liquid helium. Pressures down to 10 −8 mmHg (10 −6 Pa) can be maintained; if they are used in conjunction with a diffusion pump , pressures as low as 10 −15 mmHg (10 −13 Pa) can be...

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