PROJECT Faraday's law of induction Qianmeng Gu(qxg5019) Linnan Zhang(lqz5068) Ying Ye(yoy5069)

We all know today is an age of electricity. We enjoy the benefit the electricity provides us everywhere.

Long time ago, people burn woods, coals and petroleum to generate energy. Until 1800,Alessandro Volta invented the first true battery which came to be known as the Voltaic Pile- consisted of pairs of copper and zinc discs piled on top of each other, separated by a layer of cloth or cardboard soaked in brine. This enable human generate and utilize electricity. People used chemical cell to transfer chemical energy into electricity

Here comes a problem: Voltaic Pile could not generate a large amount of electricity, therefore electricity still could not be used widespread.

1831, Faraday and his Law of Induction made the mass production of electricity possible. Instead of chemical energy, Law of induction allow human to change mechanical energy into electricity.

The predominant theory before Law of induction In 1820, Danish physicist and chemist, Hans Christian Ørsted discovered the phenomenon of electromagnetism. In 1821 Faraday, Davy and William built homopolar motor-which made continuous circular motion from the circular magnetic force around a wire and a wire extending into a pool of mercury with a magnet placed inside that would rotate around the magnet if supplied with current from a chemical battery. This is foundation of modern electromagnetic technology

Faraday was an English chemist and physicist (or natural philosopher, in the terminology of the time) who contributed to the fields of electromagnetism and electrochemistry. Faraday is best known for his work regarding electricity and magnetism. His first recorded experiment was the construction of a voltaic pile with seven halfpence pieces, stacked together with seven disks of sheet zinc, and six pieces of paper moistened with salt water. With this pile he decomposed sulphate of magnesia (first letter to Abbott, 12 July 1812).

For the relationship between a time-varying magnetic field and an induced electric field In physics, a quantitative relationship between a changing magnetic field and the electric field created by the change, developed on the basis of experimental observations made in 1831 by the English scientist Michael Faraday.(Shown by the right side picture) Faraday discovered that, whenever the magnetic field about an electromagnet was made to grow and collapse by closing and opening the electric circuit of which it was a part, an electric current could be detected in a separate conductor nearby. Moving a permanent magnet into and out of a coil of wire also induced a current in the wire while the magnet was in motion. Moving a conductor near a stationary permanent magnet caused a current to flow in the wire, too, as long as it was moving. Faraday's law of induction

Mathematical expression For the special case of a coil of wire, composed of N loops with the same area, the equation becomes

 Faraday constructed a homopolar generator, now also known as a Faraday disk, which produces a relatively weak direct current (DC).  This has been superseded by alternating current (AC) electrical generators, which power the machinery of the modern world.  electricity is generated by the movement of a loop of wire, or disc of copper between the poles of a magnet.  This generates a current proportional to the rate of rotation, which can power a small light bulb. The disk can be rotated in either direction.  However, this design was inefficient  There are many other technologies that can be and are used to generate electricity such as solar photovoltaic and geothermal power. The fundamental principles of electricity generation is still used today!

OTHER INVENTIONS AND TECHNOLOGIES THAT INCORPORATE FARADAY’S LAW  convenience of mobile communications I.Telephone II.Microphone III.Gramophone  Mechanically-powered flashlight

IN CONCLUSION: This concept has many far-reaching ramifications that touch our lives in many ways:  Revealed the relationship of electricity and magnetic field  Convenience of daily mobile communications  Electricity to power our homes  Long distance transmission of electricity became possible. We can all appreciate the profound impact Faraday’s Law has on us.

LAST BUT NOT LEAST, Thank you for your attention

BIBLIOGRAPHY Blinder, S. M. (n.d.). Wolfeam Demonstrations Project. Retrieved Feb 20, 2012, from Electricity generation. (n.d.). Retrieved 02 10, 2012, from Logan, A. (n.d.). Faraday's law of electromagnetic induction. Retrieved 02 11, 2012, from pdf.