1. PROJECT Faraday's law of induction
RUI SHI(ROS5334)
YANSHENG WANG(YVW5162)
ZHONGYI LIU(ZVL5078)
XIAN MAO(XQM5030)
JIAJIE HUANG(JYH5353)

2. It is an age of electricity!

3. Some historcal stuff about electricity
long age, people burn woods,coals and petroleum to generate energy.
Until1800,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

4. However:
Voltaic Pile could not generate a large amount of electricity, therefore electricity still could not be used widespreadly.

5. Until 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 mechanial energy into electricity

6. First let's talk something about Faraday!
Michael Faraday, FRS (22 September 1791 – 25 August 1867) was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry.
Faraday studied the magnetic field around a conductor carrying a DC electric current.
Established the basis for the electromagnetic field concept in physics,
Discovered electromagnetic induction, diamagnetism, and laws of electrolysis.
Established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena.
As a chemist, Faraday discovered benzene, investigated the clathrate hydrate of chlorine, invented an early form of the Bunsen burner and the system of oxidation numbers, and popularised terminology such as anode, cathode, electrode, and ion.
One of the greatest scientists!!

7. The predominent theory before Law of induction (fundations of the 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

8. The breakthrought experiment
In Faraday's first experimental demonstration of electromagnetic induction (August 29, 1831) as the shown image. He wrapped the wire around the two opposite sides of the iron ring. During both the connection and disconnection of the circuit, he found out there was an electrical current going through the circuit.
After the first demonstration, Faraday was also aware the existence of an electrical current as he slid a magnet bar in and out of a coil of wire in a high frequency. and he generated a steady (DC) current by rotating a copper disk near a bar magnet with a sliding electrical lead

9. Law of Induction
After his experiment, Faladay stated that electromotive force (EMF) produced around a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path.
In practice, this means that an electric current will be induced in any closed circuit when the magnetic flux through a surface bounded by the conductor changes.
This applies whether the field itself changes in strength or the conductor is moved through it

10. Mathematical expression
where is the electromotive force
ΦB is the magnetic flux
For the special case of a coil of wire, composed of N loops with the same area, the equation becomes

11. Most important application! Electric generator!
Electric generator is is a device that converts mechanical energy to electrical energy.
Basic theory- law of induction
Magnets + Copper wire + motion = Current!
Faraday built the first electromagnetic generator, called the Faraday disk, a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet. It produced a small DC voltage.
This design was inefficient
Nowadays there are some much more efficient electric generator systems and power plant like and Coal-fired Power Plant and Combined Cycle Power plant,but the basic theory is the same!- Law of induction
faraday disk

12. Others applications of Law of Induction
Mechanically-powered flashlight
Telephone
Microphone
Gramophone
....

13. Impact on nowaday society
Reveal the relationship of electricity and magnetic feild
Make the mass production and long-distance transmission of electricity become possible, which help human entrance the age of electricity
Widely used in some daily electronic products such as phone, Law of induction make our life much better.

14. Thanks for your attention