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2001 English Greyhound Derby

The 2001 William Hill Greyhound Derby Final took place during May and June with the final being held on 2 June 2001 at Wimbledon Stadium. The winner received £75,000. Rapid Ranger defended his title and became only the third greyhound in history to win the Derby twice, he was owned by Ray White and bred by Martin Broughan. Two of the finalists Smoking Bullet and Countrywide Tams were owned by Vinnie Jones. At Wimbledon: 3¼, 1½, head, 3½, head The distances between the greyhounds are in finishing order and shown in lengths. One length is equal to 0.08 of one second. Rapid Ranger soon led and won comfortably from the strong finishing Scottish Derby champion Sonic Flight who had found trouble at the first bend along with Smoking Bullet and Droopys Honcho. Castlelyons Dani finished well for third after Countrywide Tams had a clear run. 2001 UK & Ireland Greyhound Racing Year

Homopolar motor

A homopolar motor is a direct current electric motor with two magnetic poles, the conductors of which always cut unidirectional lines of magnetic flux by rotating a conductor around a fixed axis so that the conductor is at right angles to a static magnetic field. The resulting EMF being continuous in one direction, the homopolar motor needs no commutator but still requires slip rings; the name homopolar indicates that the electrical polarity of the conductor and the magnetic field poles do not change. The homopolar motor was the first electrical motor to be built, its operation was demonstrated by Michael Faraday in 1821 at the Royal Institution in London. In 1821, soon after the Danish physicist and chemist Hans Christian Ørsted discovered the phenomenon of electromagnetism, Humphry Davy and British scientist William Hyde Wollaston tried, but failed, to design an electric motor. Faraday, having been challenged by Humphry as a joke, went on to build two devices to produce what he called "electromagnetic rotation".

One of these, now known as the homopolar motor, caused a continuous circular motion, engendered by the circular magnetic force around a wire that extended into a pool of mercury wherein was placed a magnet. The wire would rotate around the magnet if supplied with current from a chemical battery; these experiments and inventions formed the foundation of modern electromagnetic technology. In his excitement, Faraday published results; this strained his mentor relationship with Davy, due to his mentor's jealousy of Faraday's achievement, is the reason for Faraday’s assignment to other activities, which prevented his involvement in electromagnetic research for several years. B. G. Lamme described in 1913 a homopolar machine rated 2,000 kW, 260 V, 7,700 A and 1,200 rpm with 16 slip rings operating at a peripheral velocity of 67 m/s. A unipolar generator rated 1,125 kW, 7.5 V 150,000 A, 514 rpm built in 1934 was installed in a U. S. steel mill for pipe welding purposes. The homopolar motor is driven by the Lorentz force.

A conductor with a current flowing through it when placed in a magnetic field, perpendicular to the current feels a force in the direction perpendicular to both the magnetic field and the current. This force provides a torque around the axis of rotation; because the axis of rotation is parallel to the magnetic field, the opposing magnetic fields do not change polarity, no commutation is required for the conductor to keep turning. This simplicity is most achieved with single turn designs, which makes homopolar motors unsuitable for most practical applications. Like most electro-mechanical machines, a homopolar motor is reversible: if the conductor is turned mechanically it will operate as a homopolar generator, producing a direct current voltage between the two terminals of the conductor; the direct current produced is an effect of the homopolar nature of the design. Homopolar generators were extensively researched in the late 20th century as low voltage but high current DC power supplies and have achieved some success powering experimental railguns.

A homopolar motor is easy to build. A permanent magnet is used to provide the external magnetic field in which the conductor will turn, a battery causes a current to flow along a conducting wire, it is not necessary for the magnet to move, or to be in contact with the rest of the motor. One can attach the magnet to the battery and allow the conducting wire to rotate while closing the electric circuit by touching both the top of the battery and the magnet attached to the bottom of the battery; the wire and the battery may become hot. Railgun Ball bearing motor Homopolar generators Barlow's wheel