click links in text for more info
SUMMARY / RELATED TOPICS

Electrical resistivity and conductivity

Electrical resistivity and its inverse, electrical conductivity, is a fundamental property of a material that quantifies how it resists or conducts electric current. A low resistivity indicates a material that allows electric current. Resistivity is represented by the Greek letter ρ; the SI unit of electrical resistivity is the ohm-meter. For example, if a 1 m × 1 m × 1 m solid cube of material has sheet contacts on two opposite faces, the resistance between these contacts is 1 Ω the resistivity of the material is 1 Ω⋅m. Electrical conductivity or specific conductance is the reciprocal of electrical resistivity, it represents a material's ability to conduct electric current. It is signified by the Greek letter σ, but κ and γ are sometimes used; the SI unit of electrical conductivity is siemens per metre. In an ideal case, cross-section and physical composition of the examined material are uniform across the sample, the electric field and current density are both parallel and constant everywhere.

Many resistors and conductors do in fact have a uniform cross section with a uniform flow of electric current, are made of a single material, so that this is a good model. When this is the case, the electrical resistivity ρ can be calculated by: ρ = R A ℓ, where R is the electrical resistance of a uniform specimen of the material ℓ is the length of the specimen A is the cross-sectional area of the specimenBoth resistance and resistivity describe how difficult it is to make electrical current flow through a material, but unlike resistance, resistivity is an intrinsic property; this means that all pure copper wires, irrespective of their shape and size, have the same resistivity, but a long, thin copper wire has a much larger resistance than a thick, short copper wire. Every material has its own characteristic resistivity. For example, rubber has a far larger resistivity than copper. In a hydraulic analogy, passing current through a high-resistivity material is like pushing water through a pipe full of sand—while passing current through a low-resistivity material is like pushing water through an empty pipe.

If the pipes are the same size and shape, the pipe full of sand has higher resistance to flow. Resistance, however, is not determined by the presence or absence of sand, it depends on the length and width of the pipe: short or wide pipes have lower resistance than narrow or long pipes. The above equation can be transposed to get Pouillet's law: R = ρ ℓ A; the resistance of a given material is proportional to the length, but inversely proportional to the cross-sectional area. Thus resistivity can be expressed using the SI unit "ohm metre" — i.e. ohms divided by metres and multiplied by square metres. For example, if A = 1 m2, ℓ = 1 m the resistance of this element in ohms is numerically equal to the resistivity of the material it is made of in Ω⋅m. Conductivity, σ, is the inverse of resistivity: σ = 1 ρ. Conductivity has SI units of siemens per metre. For less ideal cases, such as more complicated geometry, or when the current and electric field vary in different parts of the material, it is necessary to use a more general expression in which the resistivity at a particular point is defined as the ratio of the electric field to the density of the current it creates at that point: ρ = E J, where ρ is the resistivity of the conductor material, E is the magnitude of the electric field, J is the magnitude of the current density,in which E and J are inside the conductor.

Conductivity is the inverse of resistivity. Here, it is given by: σ = 1 ρ = J E. For example, rubber is a material with large ρ and small σ—because a large electric field in rubber makes no current flow through it. On the other hand, copper is a material with small ρ and large σ—because a small electric field pulls a lot of current through it; as shown below, this expression simplifies to a single number when the electric field and current density are constant in the material. When the resistivity of a material has a directional component, the most general definition of resistivity must be used, it starts from the tensor-vector form of Ohm's law, which relates the electric field inside a material to the electric current flow. This equation is general, meaning it is valid in all cases, including those mentioned above. However, this definition is the most complicated, so it is only directly used in anisotropic cases, where the more simple definitions cannot be applied. If the material is not anisotropic, it is safe to ignore t

Hot Wheels

Hot Wheels is a brand of die-cast toy cars introduced by American toy maker Mattel in 1968. It was the primary competitor of Matchbox until 1997, when Mattel bought Tyco Toys, then-owner of Matchbox. Many automobile manufacturers have since licensed Hot Wheels to make scale models of their cars, allowing the use of original design blueprints and detailing. Although Hot Wheels were intended for children and young adults, they have become popular with adult collectors, for whom limited edition models are now made available; the original Hot Wheels were made by Elliot Handler. Hot Wheels were conceived to be more like "hot rod" cars, as compared to Matchbox cars which were small-scale models of production cars. "Sweet 16" There were sixteen castings released on May 18, 1968, eleven of them designed by Harry Bentley Bradley. The first one produced was a dark blue "Custom Camaro". Bradley was from the car industry and had designed the body for the Dodge Deora concept car and the Custom Fleetside. In 1968, the first production line of Hot Wheels Cars is known as The Original Sweet 16, the first of the Red Line Series, meaning the tires have a red pin stripe on their sides.

In addition to the cars themselves, Mattel produced a racing track set. Though it would be updated throughout the years, the original track consisted of a series of brightly colored orange road sections, with one "super chargers". An important feature here was Hot Wheel's use of wide, hard-plastic tires that created much less friction and tracked more smoothly than the narrow metal or plastic wheels used on contemporary Matchboxes; as it turned out, the Hot Wheels brand was a staggering success. The series disrupted the whole industry for small die-cast car models from 1968 onwards, forcing the competition at Matchbox and elsewhere to rethink their concepts, to scramble to try to recover lost ground. Harry Bentley Bradley did not think that would be the case and had quit Mattel to go back to the car industry; when the company asked him back, he recommended Ira Gilford. Gilford, who had just left Chrysler accepted the job of designing the next Hot Wheels models; some of Hot Wheels' greatest cars, such as the Twin Mill and Splittin' Image, came from Ira Gilford's drawing board.

The success of the 1967 line was solidified and consolidated with the 1969 releases, with which Hot Wheels established itself as the hottest brand of small toy car models in the USA. Splittin' Image, Torero and Twin Mill were part of the "Show & Go" series and are the first original in-house designs by Hot Wheels; the initial prototypes of the Beach Bomb were faithful to the shape of a real VW Type 2 "bus", had two surfboards sticking out the back window, in a nod to the VW's perceived association with the surfing community and the slang term for a person who spends much time surfing - a'beach bum'. During the fledgling Hot Wheels era, Mattel wanted to make sure that each of the cars could be used with any of the playsets and stunt track sets. Testing showed that this early version was too narrow to roll on Hot Wheels track or be powered by the Super Charger, was too top-heavy to negotiate high-speed corners. Hot Wheels designers Howard Rees and Larry Wood modified the casting, extending the side fenders to accommodate the track width, as well as providing a new place on the vehicle to store each of the plastic surfboards.

The roof was cut away and replaced by a full-length sunroof, to lower the center of gravity. Nicknamed the Side-loader by collectors, this was the production version of the Beach Bomb; the Rear-Loader Beach Bomb is considered the "Holy Grail", or ultimate pinnacle, of a serious Hot Wheels collection. An unknown number were given to employees. A regular production Beach Bomb may be worth up to $600, depending on condition. Market prices on RLBBs however, have reached the five-figure plateau, ranging from $70,000 to $120,000; the Petersen Automotive Museum in Los Angeles had a pink RLBB in its Hot Wheels exhibit, displayed alone on a rotating platform under glass. The Hot Wheels Collectors Club released a new, updated version of the Rear Loading Beach Bomb in 2002 as a limited edition. 1970 was a successful year for Hot Wheels, so Mattel came up with a new advertising slogan for the cars: "Go With the Winner". 43 new cars appeared this year. This was the year that Sizzlers and Heavyweights lines appeared.

Howard Rees, who worked with Ira Gilford, was tired of designing cars. He wanted to work on the Major Matt Mason action figure toy line-up. Rees had a good friend by the name of Larry Wood, they had worked together at Ford designing cars. When Wood found out about Hot Wheels at a party Rees was holding, Rees offered Wood the job of designing Hot Wheels models. Wood agreed, by the end of the week, Wood was working at Mattel, his first design would be the Tri-Baby. After 36 years, Wood still works for Hot Wheels. Another designer, Paul Tam, joined Gilford. Tam's first design for Hot Wheels was the Whip Creamer. Tam continued to work for Mattel until 1973. Among the many fantastic designs T

For Hope

For Hope is a 1996 ABC TV movie starring Dana Delany and directed by Bob Saget. Based on Saget's sister Gay, the movie showed the experience of a young woman fatally afflicted with the disease scleroderma. Other cast members included Chris Demetral. Dana Delany had to have some significant prosthetic makeup applied to simulate the various degrees of disfigurement the main character, experienced as a result of the disease; the original airing achieved the top Nielsen ratings for the time slot. The movie has periodically been re-rerun on various TV channels, is available on DVD and VHS for a $20 donation at the Scleroderma Research Foundation. An extra feature of the movie was that it included a cameo appearance by Scleroderma Research Foundation founder Sharon Monsky. For Hope on IMDb

Central Valley Project Water Association

The Central Valley Project is a federal power and water management project in the U. S. state of California under the supervision of the United States Bureau of Reclamation. It was devised in 1933 in order to provide irrigation and municipal water to much of California's Central Valley—by regulating and storing water in reservoirs in the northern half of the state, transporting it to the water-poor San Joaquin Valley and its surroundings by means of a series of canals and pump plants, some shared with the California State Water Project. Many CVP water users are represented by the Central Valley Project Water Association. In addition to water storage and regulation, the system has a hydroelectric capacity of over 2,000 megawatts, provides recreation and flood control with its twenty dams and reservoirs, it has allowed major cities to grow along Valley rivers which would flood each spring, transformed the semi-arid desert environment of the San Joaquin Valley into productive farmland. Freshwater stored in Sacramento River reservoirs and released downriver during dry periods prevents salt water from intruding into the Sacramento-San Joaquin Delta during high tide.

There are eight divisions of the project and ten corresponding units, many of which operate in conjunction, while others are independent of the rest of the network. California agriculture and related industries now directly account for 7% of the gross state product for which the CVP supplied water for about half. Many CVP operations have had considerable environmental consequences, including a decline in the salmon population of four major California rivers in the northern state, the reduction of riparian zones and wetlands. Many historical sites and Native American tribal lands have been flooded by CVP reservoirs. In addition, runoff from intensive irrigation has groundwater; the Central Valley Project Improvement Act, passed in 1992, intends to alleviate some of the problems associated with the CVP with programs like the Refuge Water Supply Program. In recent years, a combination of drought and regulatory decisions passed based on the Endangered Species Act of 1973 have forced Reclamation to turn off much of the water for the west side of the San Joaquin Valley in order to protect the fragile ecosystem in the Sacramento-San Joaquin Delta and keep alive the dwindling fish populations of Northern and Central California rivers.

In 2017 the Klamath and Trinity rivers witnessed the worst fall run Chinook salmon return in recorded history, leading to a disaster declaration in California and Oregon due to the loss of the commercial fisheries. The recreational fall Chinook salmon fishery in both the ocean and the Trinity and Klamath rivers was closed in 2017. Only 1,123 adult winter Chinook salmon returned to the Sacramento Valley in 2017, according to a report sent to the Pacific Fishery Management Council by the California Department of Fish and Wildlife; this is the second lowest number of returning adult winter run salmon since modern counting techniques were implemented in 2003. By comparison, over 117,000 winter Chinooks returned to spawn in 1969; the CVP stores about 13 million acre feet of water in 20 reservoirs in the foothills of the Sierra Nevada, the Klamath Mountains and the California Coast Ranges, passes about 7.4 million acre feet of water annually through its canals. Of the water transported, about 5 million acre feet goes to irrigate 3,000,000 acres of farmland, 600,000 acre feet supplies municipal uses, 800,000 acre feet is released into rivers and wetlands in order to comply with state and federal ecological standards.

Two large reservoirs, Shasta Lake and Trinity Lake, are formed by a pair of dams in the mountains north of the Sacramento Valley. Water from Shasta Lake flows into the Sacramento River which flows to the Sacramento-San Joaquin Delta and water from Trinity Lake flows into the Trinity River which leads to the Pacific Ocean. Both lakes release water at controlled rates. There, before it can flow on to San Francisco Bay and the Pacific Ocean, some of the water is intercepted by a diversion channel and transported to the Delta-Mendota Canal, which conveys water southwards through the San Joaquin Valley, supplying water to San Luis Reservoir and the San Joaquin River at Mendota Pool in the process reaching canals that irrigates farms in the valley. Friant Dam crosses the San Joaquin River upstream of Mendota Pool, diverting its water southwards into canals that travel into the Tulare Lake area of the San Joaquin Valley, as far south as the Kern River. New Melones Lake, a separate facility, stores water flow of a San Joaquin River tributary for use during dry periods.

Other smaller, independent facilities exist to provide water to local irrigation districts. The Central Valley Project was the world's largest water and power project when undertaken during Franklin D. Roosevelt's New Deal public works agenda; the Project was the culmination of eighty years of political fighting over the state's most important natural resource - Water. The Central Valley of California lies to the west of the Sierra Nevada Mountains with its annual run-off draining into the Pacific Ocean through the Sacramento–San Joaquin River Delta, it is a large receding geological floodplain moderated by its Mediterranean climate of dry summers and wet winters that includes regular major drought cycles. At the time of its construction, the project was at the center of a political and cultural battle over the state's future, it intersected with the state's ongoing war over land use, access to water rights, impacts on indigenous

Tapah Road

Tapah Road is a small town, located near Tapah, in the state of Perak, in Malaysia. The population consists of 30 % Chinese, 20 % Indians and a few indigenous. Tapah Road was of greater importance in early to mid-20th century because of its railway station, Tapah Road railway station, the second oldest in Malaysia; the station was constructed with a 30 km railway to Teluk Intan in the 1880s. The station was, still is, linked to the main railway line from Butterworth to Singapore. Tapah Road was considered a major stop because it was the gateway to Cameron Highlands, the cold highland resort, popular with the British colonial officers; the town became less important in terms of economic activities in the region as road vehicles gained popularity beginning in the 1970s. The train service between Tapah Road and Teluk Intan had been terminated in 1991 and most of the railtrack is no longer in place. Tapah Road railway station was rebuilt in 2007 as part of the duplication and electrification of the main railway line.

It is now served by the Kuala Lumpur-Ipoh Electric Train Service and the Kuala Lumpur-Butterworth KTM Intercity. The town is on the road leading to Tapah and thus led to its name; this name has drawn some criticism from local Malay linguists because it has a colonial'stain' on it. A number of towns in Perak have this'stain' such as Slim River, Port Weld and Teluk Anson. Tapah Road maintained its name because the equivalent version in Malay is not suitable because it is not named after a road, but a town; the town is now gaining significance because a large prison was built about 1 km from the town in 2001. The prison is the largest in Perak and a small township has been spawned near the prison to cater for the prison staff and visitors. There are a secondary school in this town. There are two rows of shops leading to the railway station. An overhead bridge was built over the railway lines. There are large oil palm estates near the town leading to Teluk Intan. There have two big Indian's Kuil and six small Kaliaman kuil in the estate.

There are vegetable farms and rubber estates along the road to Tapah. There were a lot of tin mines 30 years ago but not one is in operation now. There was a plan to build a university in this area but it is not known if the project is still on since there is still no evidence of its construction yet. There is a university UITM Tapah, and there is clinic opposite of the u

WondaGurl

Ebony Naomi Oshunrinde, professionally known as WondaGurl, is a Canadian record producer. WondaGurl has worked with several prominent artists in the music industry, including Mariah Carey, Lil Uzi Vert, Big Sean, Travis Scott, Jay Z, Drake, SZA, Young Thug, KILLY, Kanye West, among others. Ebony Naomi Oshunrinde was born on December 28, 1996 in Brampton, Canada, to Jozie Oshunrinde. WondaGurl started producing on her keyboard with drum pads at age 9. WondaGurl entered the 2011 and 2012 Battle of The Beat Makers competition in Toronto, which she entered at age 15 and won first place, earning a trophy and a Roland GAIA Synthesizer. WondaGurl became a protege of Boi-1da and works with Travis Scott, she sent a beat to Drake via Instagram, which landed two placements, "Used To" and "Company", featuring and co-produced by Travis Scott, on Drake's mixtape If You're Reading This It's Too Late. She sent a beat to Travis Scott, who passed it on to Jay Z, which became the song "Crown". WondaGurl has worked with other major artists and producers since and produced the Top 40 hit single "Antidote" by Travis Scott, co-produced by Eestbound.

She would go on becoming her first artist. In 2018, she was featured in the Music category of Forbes 30 Under 30, she is one of the youngest women to add production to a platinum-selling hip hop album. Ryan Leslie - Black Mozart08. "Evacuation" 00."New New"Travis Scott - Owl Pharaoh05. "Uptown" Jay Z - Magna Carta Holy Grail08. "Crown"SZA00. "Teen Spirit" Redway - Years Ahead06. "YKTO"Travis Scott - Days Before Rodeo01. "Days Before Rodeo: The Prayer" Drake - If You're Reading This It's Too Late11. "Used To" 14. "Company" Rihanna00. "Bitch Better Have My Money" Young Thug - Slime Season10 "Freaky" Juicy J - O's to Oscars12. "I Ain't Fukin Witcha" Travis Scott - Rodeo05. "90210" 09. "Antidote" Leftover 00. "High Fashion" Travis Scott 00. "The Prayer" Tre Capital - "Gundam Part II - EP" Lil Uzi Vert - Lil Uzi Vert vs. the World09. "Scott and Ramona"Sean Leon - Black Sheep Nirvana00. "This Ain't 2012" 00. "Deep End" 00. "Killin' Mind" 00. "Guard/God Up"Jahkoy Palmer00. "Odd Future"Usher00. "No Limit" Travis Scott - Birds in the Trap Sing McKnight01.

"the ends" 07. "sweet sweet" Ab-Soul - Do What Thou Wilt.02. "Braille" Lil Simz - Stillness In Wonderland10 "Bad to the Bone ""Nessly - Solo Boy Band07. "Moonwalking" Big Sean - I Decided.04. "No Favors" Lil Uzi Vert - Luv is Rage 204. "Feelings Mutual" 12. "How to Talk" 14. "Malfunction"Lil Yachty - Teenage Emotions11. "Lady in Yellow"Bryson Tiller - True to Self04. "Blowing Smoke" Cousin Stizz - One Night Only11. "Jo Bros" Rich the Kid - The World Is Yours05. "Too Gone" (featuring Khalid Travis Scott - Astroworld 06. "No Bystanders" 13. "Can't Say" JID - DiCaprio 2 14. "Hasta Luego" Mariah Carey - Caution 7. "One Mo' Gen" Don Toliver - No Idea 00. "No Idea" JackBoys, Travis Scott - JackBoys' 03. Gang Gang 04. Had Enough Maroon 5 – Girls Like You Ludwig Göransson - Killmonger WondaGurl on Twitter