Electricity and Magnetism

• Electricity – a form of energy that results from the flow of charged particles. It is the source of energy of almost all major appliances in our home.
• Magnetism – a phenomenon associated with magnetic fields, which arise from the motion of electric charges.
• In 1820, Hans Christian Oersted, a Danish physicist and chemist, accidentally discovered that an electric current can produce a magnetic field.
• 1831, Michael Faraday and Joseph Henry, physicists working independently, discovered that if an electric current can produce a magnetic field, then the reverse is also true – a changing magnetic field can produce electric current, a process called electromagnetic induction. The current and the electromotive force (emf) produced are called induced currents and induced emf.
• Electromagnetic Induction – is the process by which current is produced by a change in magnetic flux. A change in flux may be a result of change in magnetic field, a change in surface area, or a change in orientation
• To determine the direction of the magnetic field, the right-hand rule is being used.
• The discovery of the magnetic field from electricity led to the development of electromagnet.
• Electromagnet – a device composed of several coils of wire that produce a uniform magnetic field when current passes through the wire.
• Faraday’s Law – states that whenever there is a change in the magnetic flux in a circuit, and induced current (and hence induced emf) is produced.
• Magnetic Flux – refers to the number of magnetic field lines of a magnet. The induced emf is proportional to the rate of change of the magnetic flux.
• Lenz's Law states that the induced current flows in a direction so as to oppose the change causing it
• Magnetic Field – exists around a current-carrying wire.
• Electric Generator – an electric motor running in reverse. Mechanical energy is used to rotate the coil to produce electrical energy.
• Electric Motor – first appeared in the 1740s through the work of Scottish Benedictine monk and scientist, Andrew Gordon. It is a device that converts electrical energy into a mechanical energy.
• Motors and Generators – are essential for modern technology and magnetic induction is the phenomenon that makes them work.
• Generators – converts mechanical energy to electrical energy. It is sometimes called alternator.
• The French scientist Hippolyte Pixxi was credited for having made the first electric generator in 1832.
• Motors – convert electrical energy to mechanical energy.
• Nikola Tesla invented the AC motor.