Relative permittivity

The relative permittivity of a material is its permittivity expressed as a ratio relative to the vacuum permittivity. Permittivity is a material property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum. Relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is commonly known as the dielectric constant, a term still used but deprecated by standards organizations in engineering as well as in chemistry. Relative permittivity is denoted as εr and is defined as ε r = ε ε 0, where ε is the complex frequency-dependent permittivity of the material, ε0 is the vacuum permittivity. Relative permittivity is a dimensionless number, in general complex-valued; the relative permittivity of a medium is related to χe, as εr = 1 + χe.

In anisotropic media the relative permittivity is a second rank tensor. The relative permittivity of a material for a frequency of zero is known as its static relative permittivity; the historical term for the relative permittivity is dielectric constant. It is still used, but has been deprecated by standards organizations, because of its ambiguity, as some older authors used it for the absolute permittivity ε; the permittivity may be quoted either as a frequency-dependent variant. It has been used to refer to only the real component ε'r of the complex-valued relative permittivity. In the causal theory of waves, permittivity is a complex quantity; the imaginary part corresponds to a phase shift of the polarization P relative to E and leads to the attenuation of electromagnetic waves passing through the medium. By definition, the linear relative permittivity of vacuum is equal to 1, ε = ε0, although there are theoretical nonlinear quantum effects in vacuum that become non-negligible at high field strengths.

The following table gives some typical values. The relative static permittivity, εr, can be measured for static electric fields as follows: first the capacitance of a test capacitor, C0, is measured with vacuum between its plates. Using the same capacitor and distance between its plates, the capacitance C with a dielectric between the plates is measured; the relative permittivity can be calculated as ε r = C C 0. For time-variant electromagnetic fields, this quantity becomes frequency-dependent. An indirect technique to calculate εr is conversion of radio frequency S-parameter measurement results. A description of used S-parameter conversions for determination of the frequency-dependent εr of dielectrics can be found in this bibliographic source. Alternatively, resonance based effects may be employed at fixed frequencies; the relative permittivity is an essential piece of information when designing capacitors, in other circumstances where a material might be expected to introduce capacitance into a circuit.

If a material with a high relative permittivity is placed in an electric field, the magnitude of that field will be measurably reduced within the volume of the dielectric. This fact is used to increase the capacitance of a particular capacitor design; the layers beneath etched conductors in printed circuit boards act as dielectrics. Dielectrics are used in RF transmission lines. In a coaxial cable, polyethylene can be used between outside shield, it can be placed inside waveguides to form filters. Optical fibers are examples of dielectric waveguides, they consist of dielectric materials that are purposely doped with impurities so as to control the precise value of εr within the cross-section. This controls the refractive index of the material and therefore the optical modes of transmission. However, in these cases it is technically the relative permittivity that matters, as they are not operated in the electrostatic limit; the relative permittivity of air changes with temperature and barometric pressure.

Sensors can be constructed to detect changes in capacitance caused by changes in the relative permittivity. Most of this change is due to effects of temperature and humidity as the barometric pressure is stable. Using the capacitance change, along with the measured temperature, the relative humidity can be obtained using engineering formulas; the relative static permittivity of a solvent is a relative measure of its chemical polarity. For example, water is polar, has a relative static permittivity of 80.10 at 20 °C while n-hexane is non-polar, has a relative static permittivity of 1.89 at 20 °C. This information is important when designing separation, sample preparation and chromatography techniques in analytical chemistry; the correlation should, however, be treated with caution. For instance, dichloromethane has a value of

Loren Hibbs

Loren Hibbs is an American baseball player and coach. He is the Assistant Athletics Director for Baseball Operations and Player Development for Wichita State, he has served as the head baseball coach at Charlotte. Hibbs played college baseball for Wichita State. During his time as a player with the Shockers, he was on the all-tournament team at the 1982 College World Series and, in 1982, set the NCAA record for runs in a season. After college, Hibbs played a short time in the San Francisco Giants farm system, appearing in 39 games for the Everett Giants in 1984. Hibbs served as an assistant with Wichita State from 1985–1992 before being hired by the 49ers. At Charlotte, Hibbs won the Metro Conference tournament and an NCAA Tournament berth in 1993, the Metro regular season titles in 1994 and 1995, the Atlantic 10 regular season and conference tournament titles in 2007 and 2008, the Atlantic 10 regular season title in 2010. In 1998 the Niners reached the NCAA Tournament. Charlotte broke the 1998 mark for wins in 2007 with 49 wins, including two wins over NC State in the 2007 NCAA Tournament.

On June 14, 2019, Hibbs announced his retirement as head coach of Charlotte baseball. Below is a table of Hibbs's yearly records as an NCAA head baseball coach. Hibbs's wife, Lisa, is the director of the Athletic Academic Center at UNC Charlotte, his son Tyson Hibbs played for his father as a utility player and pinch runner with the 49ers from 2006 to 2009. He is the father of two daughters and Lanie. List of current NCAA Division I baseball coaches

Annie Booth

Annie Booth is an American jazz pianist and educator. Since the age of 16, she studied with pianistJeff Jenkins and Art Lande, she studied at the Colorado Conservatory for the Jazz Arts and went on to earn a BM in Jazz Studies from the Thompson Jazz Studies Program at the University of Colorado Boulder in 2011. She was named "Best In Denver - Jazz" from Westword in 2015, 2016 and 2017. In 2016, she toured Mexico with the New York Jazz All Stars - Greg Gisbert Quartet that included musicians Greg Gisbert, Tommy Campbell, Mike Boone, she has arranged and performed with Yamaha Artist, Bob Montgomery. She has opened for jazz pianist, Joey AlexanderAnnie Booth was awarded the 2017 Herb Alpert Young Jazz Composer Award and the 2017 ASCAP Foundation Phoebe Jacobs Prize by the American Society of Composers and Publishers, her trio has performed and toured all over North America, has appeared at numerous jazz clubs and festivals including the South by Southwest festival in 2017 and as the first artist-in-residence at Nocturne Jazz & Supper Club.

In 2015 she was featured as part of KUVO's 30 Under 30 program. Annie Booth has performed on movie soundtracks, such as her work on Our Souls at Night starring Jane Fonda and Robert Redford. In 2019 she was selected for the "2020 Young Composer" Showcase by the Jazz Education Network and her composition "Jolly Beach" will be performed by The U. S. Navy Band Commodores at the 2020 conference in New Orleans, LA. Since 2015, Annie Booth has worked with The Colorado Conservatory for the Jazz Arts, a non-profit jazz education outreach organization for middle and high school students. In 2017, she created the SheBop jazz program, a series of jazz workshops and clinics for young woman, ages 10–18. Wanderlust Festive Abundance The Annie Booth Trio with Max Wellman Bob Montgomery - La Familia: The Music of Bob Montgomery Tom Gershwin - Live at Mighty Fine Jason Klobnak - New Chapter Ryan Fourt - Big Slick Jeff Riley - Jazz Suite Paul Mullikin - Time Is Now Official site