Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. In early days, electricity was considered as being not related to magnetism. On, many experimental results and the development of Maxwell's equations indicated that both electricity and magnetism are from a single phenomenon: electromagnetism. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others; the presence of an electric charge, which can be either positive or negative, produces an electric field. The movement of electric charges produces a magnetic field; when a charge is placed in a location with a non-zero electric field, a force will act on it. The magnitude of this force is given by Coulomb's law. Thus, if that charge were to move, the electric field would be doing work on the electric charge, thus we can speak of electric potential at a certain point in space, equal to the work done by an external agent in carrying a unit of positive charge from an arbitrarily chosen reference point to that point without any acceleration and is measured in volts.
Electricity is at the heart of many modern technologies, being used for: electric power where electric current is used to energise equipment. Electrical phenomena have been studied since antiquity, though progress in theoretical understanding remained slow until the seventeenth and eighteenth centuries. Practical applications for electricity were few, it would not be until the late nineteenth century that electrical engineers were able to put it to industrial and residential use; the rapid expansion in electrical technology at this time transformed industry and society, becoming a driving force for the Second Industrial Revolution. Electricity's extraordinary versatility means it can be put to an limitless set of applications which include transport, lighting and computation. Electrical power is now the backbone of modern industrial society. Long before any knowledge of electricity existed, people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BCE referred to these fish as the "Thunderer of the Nile", described them as the "protectors" of all other fish.
Electric fish were again reported millennia by ancient Greek and Arabic naturalists and physicians. Several ancient writers, such as Pliny the Elder and Scribonius Largus, attested to the numbing effect of electric shocks delivered by catfish and electric rays, knew that such shocks could travel along conducting objects. Patients suffering from ailments such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them; the earliest and nearest approach to the discovery of the identity of lightning, electricity from any other source, is to be attributed to the Arabs, who before the 15th century had the Arabic word for lightning ra‘ad applied to the electric ray. Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, could be rubbed with cat's fur to attract light objects like feathers. Thales of Miletus made a series of observations on static electricity around 600 BCE, from which he believed that friction rendered amber magnetic, in contrast to minerals such as magnetite, which needed no rubbing.
Thales was incorrect in believing the attraction was due to a magnetic effect, but science would prove a link between magnetism and electricity. According to a controversial theory, the Parthians may have had knowledge of electroplating, based on the 1936 discovery of the Baghdad Battery, which resembles a galvanic cell, though it is uncertain whether the artifact was electrical in nature. Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert wrote De Magnete, in which he made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber, he coined the New Latin word electricus to refer to the property of attracting small objects after being rubbed. This association gave rise to the English words "electric" and "electricity", which made their first appearance in print in Thomas Browne's Pseudodoxia Epidemica of 1646. Further work was conducted in the 17th and early 18th centuries by Otto von Guericke, Robert Boyle, Stephen Gray and C. F. du Fay.
In the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a metal key to the bottom of a dampened kite string and flown the kite in a storm-threatened sky. A succession of sparks jumping from the key to the back of his hand showed that lightning was indeed electrical in nature, he explained the paradoxical behavior of the Leyden jar as a device for storing large amounts of electrical charge in terms of electricity consisting of both positive and negative charges. In 1791, Luigi Galvani published his discovery of bioelectromagnetics, demonstrating that electricity was the medium by which neurons passed signals to the muscles. Alessandro Volta's battery, or voltaic pile, of 1800, made from alternating layers of zinc and copper, provided scientists with a more reliable source of electrical energy than the electrostatic machines used; the recognition of electromagnetism, the unity of electric
A toy is an item, used in play one designed for such use. Playing with toys can be an enjoyable means of training young children for life in society. Different materials like wood, clay and plastic are used to make toys. Many items are designed to serve as toys, but goods produced for other purposes can be used. For instance, a small child may fold an ordinary piece of paper into an airplane shape and "fly it". Newer forms of toys include interactive digital entertainment; some toys are produced as collectors' items and are intended for display only. The origin of toys is prehistoric; the origin of the word "toy" is unknown, but it is believed that it was first used in the 14th century. Toys are made for children; the oldest known doll toy is thought to be 4,000 years old. Playing with toys is considered to be important when it comes to growing up and learning about the world around us. Younger children use toys to discover their identity, help their bodies grow strong, learn cause and effect, explore relationships, practice skills they will need as adults.
Adults on occasion use toys to form and strengthen social bonds, help in therapy, to remember and reinforce lessons from their youth. Most children have been said to play such as sticks and rocks. Toys and games have been unearthed from the sites of ancient civilizations, they have been written about in some of the oldest literature. Toys excavated from the Indus valley civilization include small carts, whistles shaped like birds, toy monkeys which could slide down a string; the earliest toys are made from materials found in nature, such as rocks and clay. Thousands of years ago, Egyptian children played with dolls that had wigs and movable limbs which were made from stone and wood. In Ancient Greece and Ancient Rome, children played with dolls made of wax or terracotta, sticks and arrows, yo-yos; when Greek children girls, came of age it was customary for them to sacrifice the toys of their childhood to the gods. On the eve of their wedding, young girls around fourteen would offer their dolls in a temple as a rite of passage into adulthood.
The oldest known mechanical puzzle comes from Greece and appeared in the 3rd century BCE. The game consisted of a square divided into 14 parts, the aim was to create different shapes from these pieces. In Iran "puzzle-locks" were made as early as the 17th century. Toys became more widespread with the changing attitudes towards children engendered by the Enlightenment. Children began to be seen as people in and of themselves, as opposed to extensions of their household and that they had a right to flourish and enjoy their childhood; the variety and number of toys that were manufactured during the 18th century rose. He created puzzles on eight themes – the World, Asia, America and Wales, Ireland and Scotland; the rocking horse was developed at the same time in England with the wealthy as it was thought to develop children's balance for riding real horses. Blowing bubbles from leftover washing up soap became a popular pastime, as shown in the painting The Soap Bubble by Jean-Baptiste-Siméon Chardin.
Other popular toys included hoops, toy wagons, spinning wheels and puppets. The first board games were produced by John Jefferys in the 1750s, including A Journey Through Europe; the game was similar to modern board games. In the nineteenth century, the emphasis was put on toys that had an educational purpose to them, such as puzzles, books and board games. Religiously themed toys were popular, including a model Noah's Ark with miniature animals and objects from other Bible scenes. With growing prosperity among the middle class, children had more leisure time on their hands, which led to the application of industrial methods to the manufacture of toys. More complex mechanical and optics-based toys were invented. Carpenter and Westley began to mass-produce the kaleidoscope, invented by Sir David Brewster in 1817, had sold over 200,000 items within three months in London and Paris; the company was able to mass-produce magic lanterns for use in phantasmagoria and galanty shows, by developing a method of mass production using a copper plate printing process.
Popular imagery on the lanterns included royalty and fauna, geographical/man-made structures from around the world. The modern zoetrope was invented in 1833 by British mathematician William George Horner and was popularized in the 1860s. Wood and porcelain dolls in miniature doll houses were popular with middle class girls, while boys played with marbles and toy trains; the golden age of toy development was at the turn of the 20th century. Real wages were rising in the Western world, allowing working-class families to afford toys for their children, industrial techniques of precision engineering and mass production was able to provide the supply to meet this rising demand. Intellectual emphasis was increasingly being placed on the importance of a wholesome and happy childhood for the future development of children. William Harbutt, an English painter, invented plasticine in 1897, in 1900 commercial production of the material as a children's toy began. Frank Hornby was a visionary in toy development and manufacture and was responsible for the invention and production of
Ontario is a city located in southwestern San Bernardino County, California, 35 miles east of downtown Los Angeles and 23 miles west of downtown San Bernardino, the county seat. Located in the western part of the Inland Empire metropolitan area, it lies just east of Los Angeles County and is part of the Greater Los Angeles Area; as of the 2010 Census, the city had a population of 163,924, up from 158,007 at the 2000 census, making it the county's fourth most populous city after San Bernardino and Rancho Cucamonga. The city is home to the Ontario International Airport, the 15th busiest airport in the United States by cargo carried. Ontario handles the mass of freight traffic between the ports of Los Angeles and Long Beach and the rest of the country, it is the home of Ontario Mills and former home of the Ontario Motor Speedway. It takes its name from the Ontario Model Colony development established in 1882 by the Canadian engineer George Chaffey and his brothers William Chaffey and Charles Chaffey.
They named the settlement after their home province of Ontario. The area, now Ontario was part of the lands used for hunting and foraging by the semi-nomadic Tongva Native Americans, who were known to roam as far south as the western San Bernardino Mountains. At the time of Mexican and of American settlement, active Native American settlements were scattered across the entire valley. Remains of a Serrano village were discovered in the neighboring foothills of the present-day city of Claremont. Juan Bautista de Anza is said to have passed through the area on his 1774 expedition, to this day a city park and a middle school bear his name. Following the 1819 establishment of San Bernardino Asistencia, which may have served as an outpost of the San Gabriel mission, it became part of a large, vaguely identified area called "San Antonio". In 1826, Jedediah Smith passed through what is now Upland on the first overland journey to the West coast of North America via the National Old Trails Road; the 1834 secularization of California land holdings resulted in the land's transferral to private hands.
In 1881, the Chaffey brothers and William, purchased the land and the water rights to it. They engineered a drainage system channeling water from the foothills of Mount San Antonio down to the flatter lands below that performed the dual functions of allowing farmers to water their crops and preventing the floods that periodically afflict them, they created the main thoroughfare of Euclid Avenue, with its distinctive wide lanes and grassy median. The new "Model Colony" was conceived as a dry town, early deeds containing clauses forbidding the manufacture or sale of alcoholic beverages within the town; the two named the town "Ontario" in honor of the province of Ontario in Canada, where they were born. Ontario attracted ailing Easterners seeking a drier climate. To impress visitors and potential settlers with the "abundance" of water in Ontario, a fountain was placed at the Southern Pacific railway station, it was turned on when passenger trains were approaching and frugally turned off again after their departure.
The original "Chaffey fountain", a simple spigot surrounded by a ring of white stones, was replaced by the more ornate "Frankish Fountain", an Art Nouveau creation now located outside the Ontario Museum of History and Art. Agriculture was vital to the early economy, many street names recall this legacy; the Sunkist plant remains as a living vestige of the citrus era. The Chaffey brothers left to found the settlements of Mildura and Renmark, which met with varying success. Charles Frankish continued their work at Ontario. Mining engineer John Tays refined the design of the novel "mule car", used from 1887 for public transportation on Euclid Avenue to 24th Street. At that point, the two mules were loaded onto a platform at the rear of the car and allowed to ride, as gravity propelled the trolley back down the avenue to the downtown Ontario terminus. Soon replaced by an electric streetcar, the mule car is commemorated by a replica in an enclosure south of C Street on the Euclid Avenue median. Ontario was incorporated as a city in 1891, North Ontario broke away in 1906, calling itself Upland.
Ontario grew at an astronomical rate. The population of 20,000 in the 1960s again grew 10 times more by the year 2007. Ontario was viewed as an "Iowa under Palm trees", with a solid Midwestern/Mid-American foundation, but it had a large German and Swiss community. Tens of thousands of European immigrants came to work in agriculture, in the early 1900s the first Filipinos and Japanese farm laborers arrived to display nursery ownership skills. Ontario has over two centuries of Hispanic residents, starting from the Californio period of Spanish colonial and Mexican rule in the 1840s. However, the first wave of Mexican settlers was in the 1880s brought as workers in the railroad industry and another wave from the Mexican Revolution of the 1910s. Mexican Americans resided in the city's poorer central side facing Chino. In the years following Ontario's founding, the economy was driven by its reputation as a health resort. Shortly thereafter, citrus farmers began taking advantage of Ontario's rocky soil to plant lemon and orange groves.
Agricultural opportunities attracted vintners and olive growers. The Graber Olive House, which continues to produce olives, is a city historical landmark and one of the
Electronic speed control
An electronic speed control or ESC is an electronic circuit that controls and regulates the speed of an electric motor. It may provide reversing of the motor and dynamic braking. Miniature electronic speed controls are used in electrically powered radio controlled models. Full-size electric vehicles have systems to control the speed of their drive motors. An electronic speed control follows a speed reference signal and varies the switching rate of a network of field effect transistors. By adjusting the duty cycle or switching frequency of the transistors, the speed of the motor is changed; the rapid switching of the transistors is what causes the motor itself to emit its characteristic high-pitched whine noticeable at lower speeds. Different types of speed controls brushless DC motors. A brushed motor can have its speed controlled by varying the voltage on its armature. A brushless motor requires a different operating principle; the speed of the motor is varied by adjusting the timing of pulses of current delivered to the several windings of the motor.
Brushless ESC systems create three-phase AC power, as in a variable frequency drive, to run brushless motors. Brushless motors are popular with radio controlled airplane hobbyists because of their efficiency, power and light weight in comparison to traditional brushed motors. Brushless AC motor controllers are much more complicated than brushed motor controllers; the correct phase varies with the motor rotation, to be taken into account by the ESC: Usually, back EMF from the motor is used to detect this rotation, but variations exist that use magnetic or optical detectors. Computer-programmable speed controls have user-specified options which allow setting low voltage cut-off limits, acceleration and direction of rotation. Reversing the motor's direction may be accomplished by switching any two of the three leads from the ESC to the motor. ESCs are rated according to maximum current, for example, 25 amperes or 25 A; the higher the rating, the larger and heavier the ESC tends to be, a factor when calculating mass and balance in airplanes.
Many modern ESCs support nickel metal hydride, lithium ion polymer and lithium iron phosphate batteries with a range of input and cut-off voltages. The type of battery and number of cells connected is an important consideration when choosing a battery eliminator circuit, whether built into the controller or as a stand-alone unit. A higher number of cells connected will result in a reduced power rating and therefore a lower number of servos supported by an integrated BEC, if it uses a linear voltage regulator. A well designed BEC using a switching regulator should not have a similar limitation. Large, high-current ESCs are used in electric cars, such as the Nissan Leaf, Tesla Roadster, Model S, Model X, Model 3, the Chevrolet Bolt; the energy draw is measured in kilowatts. Most mass-produced electric cars use AC motors, which allow the ESC to capture energy when the car coasts, using the motor as a generator and slowing the car down; the captured energy is used to thus extend the driving range of the car.
In some vehicles, such as those produced by Tesla, this can be used to slow down so that the car's conventional brakes are only needed at low speeds. In others, such as the Nissan Leaf, there is only a slight "drag" effect when coasting, the ESC modulates the energy capture in tandem with the conventional brakes to bring the car to a stop; some custom-built electric cars use DC motors instead of AC, because of their lower cost and simpler wiring. However, DC motors cannot be used for regenerative braking, so these vehicles cannot travel as far on the same battery, all other factors being equal. DC motors cannot safely run at RPMs as high as AC motors can, so many custom-built electric cars retain a multi-speed transmission of some kind. Since electric motors have full torque from zero RPM, the vehicle can still start off in a high gear, but starting in a lower gear allows for quicker acceleration, lower current draw and less wear and tear on the motor; this is a limited view of the system. However it is easier to increase the motor size so that the maximum torque is acceptable since the weight of a transmission can be equal to the motor.
ESCs used in mass-produced electric cars with AC motors have reversing capability, allowing the motor to run in both directions. The car has only one gear ratio, the motor runs in the opposite direction to make the car go in reverse; some custom-built electric cars with DC motors have this feature, using an electrical switch to reverse the direction of the motor, but others run the motor in the same direction all the time and use a traditional manual or automatic transmission to reverse direction (usually this is easier, since the vehicle used for the conversion has the transmission, the electric
A stadium truck is a small, off-road radio-controlled car, either rear wheel drive or four wheel drive. Stadium trucks are distinct from other types of off-road R/C vehicles, such as buggies and short course trucks, by their combination of truck-style bodies and open-wheeled layout; the construction of most manufacturers' stadium trucks, are similar to those of buggies. Most feature wheels and tires that are both larger in diameter and wider for increased ground clearance and improved handling and stability; the chassis of most electric powered models is constructed of plastic or a fiber/plastic composite while internal combustion powered models have chassis made of aluminum. Their appearance loosely resembles that of short-course trucks; the primary difference is that the tires and suspension components extend far outboard of the body, similar to open wheel race cars. Short course trucks, a similar type of R/C car, much more resemble full-size trophy trucks. Although stadium trucks have no direct full-size counterpart, their name refers to types of full-size R/C vehicles that are raced on a closed circuit or stadium rather than a long, outdoor road course.
The R/C vehicles themselves are often raced in an indoor, stadium-like setting. 1:10 radio-controlled off-road buggy
Radio controlled cars are battery/gas-powered model cars or trucks that can be controlled from a distance using a specialized transmitter or remote. The term "R/C" has been used to mean both "remote controlled" and "radio controlled", where "remote controlled" includes vehicles that are connected to their controller by a wire, but common use of "R/C" today refers to vehicles controlled by a radio-frequency link; this article focuses on radio-controlled vehicles only. Cars are powered by various sources. Electric models are powered by small but powerful electric motors and rechargeable nickel-cadmium, nickel metal hydride, or lithium polymer cells. There are brushed or brushless electric motors. Most fuel-powered models use glow plug engines, small internal combustion engines fueled by a special mixture of nitromethane and oil; these are referred to as "nitro" cars. Exceptionally large models have been introduced that are powered by small gasoline engines, similar to string trimmer motors, which use a mix of oil and gasoline.
Electric cars are considered easier for the novice to work with compared to fuel-driven models, but can be as complex at the higher budget and skill levels. In both of these categories, both on-road and off-road vehicles are available. Off-road models, which are built with functional off-road suspensions, a wide tire selection, can be used on various types of terrain. On-road cars, with a much less robust suspension, are limited to smooth, paved surfaces. In the past decade, advances in "on-road" vehicles have made their suspension as adjustable as many full scale race cars, today. Toy-grade R/C cars are manufactured with a focus on design coupled with reducing production costs. Where as a hobby-grade car has separate electronic components that are individually replaceable if they fail, toy grade cars are made with components harder to find as spare parts and a single electronic circuit board integrated into the design of the vehicle. Although hobby-grade enthusiasts look down on toy-grade R/C cars, their maintenance is much easier than that of the hobby-grade models since number of components is drastically smaller, parts can be harvested at no cost from any R/C toy car of the similar size.
Performance tends to depend on price, but with addition of hobby-grade type of batteries toy R/C cars can get up to 1/2 the speed of comparable hobby-grade car for 1/5 of the price. Stock toy-grade cars are equipped with weaker motors and are powered by alkaline or NiCad batteries which means their top speed is only 5–15 mph. Cheaper ones lack any form of a suspension and the ones that do feature a suspension have primitive or rudimentary designs. Steering is not proportional and there is no proportional "throttle" either, with stopped and full power being the only options. With all the disadvantages, toy-grade R/C cars are a great intro to the hobby for ages 5–10, are cheap platform for modifications and tuning for older enthusiasts. In recent years, hobby-grade "ready-to-run" models have become available from major manufacturers of radio-controlled cars, attracting many hobbyists who would otherwise not have purchased a kit car. Vehicles of this type need little or no final assembly and in most cases, the bodies are shipped painted and trimmed.
Safety inspection of the product to ensure correct operation is essential, as injury to operators or bystanders from disassembling vehicles is possible. A number of cars and trucks are presently available only in ready-to-run form; the growing popularity of the RTR vehicle has prompted many manufacturers to discontinue production of kit vehicles. High-spec racing vehicles are still available or sold only as kits, companies like Thunder Tiger, Losi, HPI, Traxxas and Tamiya sell kit and RTR versions with the benefits of a kit version being in upgraded parts or lower costs, respectively. Hobby grade vehicles can cost much more, ranging from $90 to over $2000. Ready-to-run, As the name suggests, are pre-assembled models ready for immediate use, they reach to speeds of about 70 miles per hour, with some modified versions capable of reaching 100 miles per hour. There are versions that run on nitro. Ready To Run Cars, Commonly known as, the "Assemble it yourself" cars, they are customizable, you can assemble the parts on your own, they are ideal because you can acquire new spares for broken parts and you can modify some features to improve performance.
They are used by professional RC drivers, you may opt for the ready to run as a beginner as it helps you develop your understanding for how the different parts work and how to fix them. Electrically powered models utilize mechanical or electronic speed control units to adjust the amount of power delivered to the electric motor; the power delivered is proportional to the amount of throttle called for by the transmitter - the more you pull the trigger, the faster it goes. The voltage is "pulsed" using transistors to produce varying output with smooth transitions and greater efficiency. Electronic speed controllers use solid state components to regulate duty cycle, adjusting the power delivered to the electrical motor. In addition, most electronic speed controllers can use the electric motor as a magnetic brake, offering better control of the model than is possible with a mechanical speed control. Mechanical speed controllers use a network of resistors and switch between them by rotating a head with an electrode around a plate that has electrical contacts.
Mechanical speed controllers are prone