9.1

• Hans Christian Oersted’s - continued to seek ways on how a magnetic field could produce an electric current.
• Hans Christian Oersted’s- He theorized that electricity can be “induced magneto-electrically
• He devised an experiment using this in Thames River and Waterloo Bridge.
• His experiment became a groundwork for the development of magneto-hydrodynamic power generation
• magneto-hydrodynamic power generation- conversion of fluid’s kinetic energy into electrical energy through electromagnetic induction.
• Electromagnetic induction is used in generators, transformers, and even in magnetic card stripes in IDs and ATM cards
• ● Faraday’s Law provides the mathematics for electromagnetic induction. ●It explains how a changing magnetic flux generates an “induced electromagnetic force in a circuital loop.
• Electromagnetic induction refers to the process in which either a conductor or a magnetic field is kept varying to produce an electromotive force or emf across the current-carrying conductor.
• These two scientists conducted several experiments about magnetically-induced electromotive force: Michael Faraday, Joseph Henry
• ●When the magnet is yet untouched, no current is observed.
• ●This is called induced current, and the electromotive force that causes it is called an induced emf.
• As the magnet is being moved to and fro the solenoid, current is generated
• ● Electromagnetic induction is also observed when solenoids are (1) connected to a galvanometer and (2) placed between the poles of an electromagnet.
• Varying the magnetic field resulted in the ff. observations:

  1. Zero current in the electromagnet yielded no magnetic field (B = 0). 2. Turning on the electromagnet allowed current to flow through temporarily (B increases). 3. The current once again returns to zero as the magnetic field B eases.
• Varying the magnetic field resulted in the ff. observations:

  4.Decreasing or increasing the solenoid’s cross-sectional area by compressing and decompressing it allows the current to flow through (during the deformation). 5. Rotating the solenoid back and forth, and or thrusting it out of the field, also permitted current to flow through.
• 9. Induced emfs that cause current are not affected by the composition of a material but by its geometry and magnetic field, and current may only be induced when these are manipulated, as shown.
• A changing magnetic flux ΦB, as observed in the results of the experiments, causes a change of the magnetic field over a period of time. The rate of this change is proportional to the electromotive force induced in the circuit
• ●A generator converts heat, mechanical, or chemical energy into electrical energy.
• ●A dynamo refers to a generator that transforms mechanical energy into electricity.
• Stator - contains a pair of plates connected to the axle.
• Rotor - made of coiling wires around metal core poles
• ●The stator works with the rest of the device to allow the induced current to flow through the system. Electromotive force is generated once the shaft and the coil begin to rotate around the shaft.
• Transformers

  ●It permits electricity to be transmitted from long distances.
• Transformers

  ●The Law of Induction accounts for the reduction of electric current as the power is kept constant, thus permitting the increase of voltage and the decrease of current or the opposite.
• ●It uses coils with varying number of loops connected by a metal conductor, which allows the magnetic flux to pass through from one coil to another.This causes the induction of emf in the second coil (Transformers)
• Eddy Currents

  ●It is also called Foucault’s current.●It contains loops of induced electrical current caused by changing magnetic field within the device.
• Eddy Currents

  ●The current “whirls” as the electrons in its plane wind at right angles to the magnetic field.
• Eddy Currents

  ●It is commonly used in the brakes of trains.●The metal wheels are subjected to the magnetic field through an electromagnet, which then induces eddy currents into the wheels as the train slows down to a halt.
• Magnetic Card Stripes

  ●These are magnetized layers that have different magnetic field orientations that store encoded information.