Electricity and MagnetismMagnets are like electrically charged objects in that like ends of the magnet repel(north repels north and south repels south)and unlike ends of the magnet attract ( north is attracted to south). There are two types of magnets: (1) Permanent magnets–are an alloy of iron and lodestone or magnetite . Permanent magnets occur naturally and (2) electric magnets – they are man made and are created by pushing electrons through wire wound in a coil. Pushing more current and creating more coils makes the electric magnet stronger.

All magnets have a limited region around them in which they will push or pull other magnetic objects and this region is called the Magnetic field . The magnetic field is strongest at the north and south poles of the magnet. All magnets have a north and south pole. One large magnet can be broken into many small magnets and each of the small magnets will still have a north and south pole.

The earth is a giant magnet with a north and a south pole. The geographic north pole (Alaska) is actually the magnetic south pole and the geographic south pole (Antarctica) is actually the magnetic north pole. A Compass is a magnet free to spin and the compasses north magnetic pole is attracted to and will spin until it points to the earth’s magnetic south pole.

Nails and other iron objects can be made into temporary magnets. Temporary magnets and permanent magnets have their atoms with aligned magnetic poles, these aligned Magnetic poles are called the magnetic domains. If you strike temporary or permanent magnets hard or often their atoms will get out of alignment and will cause the object to lose its magnetic properties. Heating a magnetic will also get its magnetic domains out of alignment and it will no longer be a magnet.

We have already stated that electric current moving through a wire produces a magnetic field. The direction the current moves determines the poles of the magnet. Reversing the current direction reverses the poles. Electromagnets are very useful because their poles are easily reversed by flipping a switch to reverse current direction. They can be turned on and off by starting and stopping the current and they can be made stronger or weaker by increasing or decreasing the amount of current.

The modern world could not operate without electromagnets. All meters that measure electricity use a permanent magnet and a electromagnet. The electromagnet is free to turn or pivot and is attached to the needle or arm of the meter. The electromagnet does not become a magnet until current runs through it, the more current the stronger the electromagnet becomes and the further the needle moves. The meter is calibrated to measure this force of attraction between the electromagnet and the permanent magnet.

Meters are wired with different circuits to allow them to measure different properties of electricity. Ammeters –are wired in series to measure the total number of electrons flowing through a wire. Ammeters measure current in amps. Voltmeters measure the push on electrons in volts and are wired in parallel to measure the push in each separate branch of the circuit. Ohm meters – measure resistance in ohms.

Motors- also use an electromagnet and a permanent magnet to turn electrical energy into mechanical energy or motion. Electric motors are found in most household appliances such as: fans, blenders, vacuum cleaners, etc. The electromagnet in motors has its poles reversed by a commutator which is a switch that rotates with the electromagnet. The north end of the permanent magnet attracts and pulls the south end of the electromagnet. When the south and north ends line up the commutator reverses the current which reverses the poles..

Now north and north are aligned. These two like poles repel which pushes the electromagnet, that is attached to a turning shaft, away completing the circle. The commutator will again switch current ,which switches poles, and the process continues much like a dog chasing his tail. Coiling the wire cause the magnetic fields to overlap and this produces a stronger magnet than current running through a straight wire produces

Most electricity comes from burning coal which turns the chemical potential energy of coal into thermal energy of heat and steam. The thermal energy of steam is used to turn turbine blades. This moving turbine is mechanical energy and it is used to move a magnet inside a coil of wire which generates electricity. Electrical energy can then be converted into sound energy with a CD player, heat, or almost any other form of energy. Once scientists learned that moving electrons (electricity) could become a magnet (electromagnet), they then discovered that moving a magnet inside a coil of wire could cause the electrons in the wire coil to move creating electricity. This process is called electromagnetic induction and use a magnet and a coil of wire called a solenoid to produce a constant electric current.

Reversing the pole on the magnet causes the direction of electric current to reverse. Moving the magnet back and forth can produce alternating current A/C.

A generator is a device that produces electricity by rotating a coil of wire inside a magnetic field. It is just the opposite of an electric motor (which turns electricity into motion). A generator turns motion into electricity (mechanical energy into electrical energy). The power companies use the motion of water flowing over a dam, or they create steam to spin their turbines. Wind from windmills can also be used to spin electrical turbines. Batteries, like generators will cause electrons to move along a wire producing electricity. Except batteries produce direct current D/C while generators produce alternating current A/C. Electricity produced by power company generators produce A/C current that alternates 120 times a second or is on 60 cycles( 60 Hz).

To get electricity to travel from the power company to your house it has to be pushed with high voltage. This much voltage must then be decreased before it enters your house, for safety reasons. A Transformer can increase or decrease voltage --or the push on electrons. A step up transformer increase voltage and a step down transformer decreases voltage. These transformers will work either way depending on the direction the current enters the transformer. Examples of transformers can be found on the tops of telephone poles and look like trash barrels attached to the pole. Transformers work by increasing or decreasing the number of electrons being pushed down a wire..

To increase the number of electrons we increase the number of wire coils. To decrease the number of electrons we decrease the number of wire coils. Both coils (primary and secondary) must be attached to the same piece of iron core which will become a magnet when either coil has electricity running through it. Alternating current will cause the electrons in the iron core (now an electromagnet) to move back and forth. These moving electrons have the same effect as moving the magnet itself and moving the magnet will cause the electrons in the wire coil to move.Step down transformer Step up transformer

Any amount of voltage can be produced in a transformer by adding or subtracting coils of wire. Direct current cannot be used in a transformer because the magnetic field produced by D/C current doesn’t reverse its poles like alternating current does.All conductors currently used to carry electricity have some resistance and resistance causes some of the electrical energy to be wasted as heat or thermal energy. It has recently been discovered that cooling certain materials to near absolute zero (0 Kelvin) will cause the material to become a Superconductor – and offer no resistance to electricity. Superconductors lose no electricity as heat unlike copper wire which can lose 10% of the electrical energy to heat energy

. The main problem with superconductors are that they have to be very cold, and superconductor materials are often brittle and hard to shape into wire. Experiments have been performed that cause passenger trains to Levitate – float in air using magnetic forces. The train has large magnets attached to their side, underside and the rails (track) is also made of a superconductor that becomes a very powerful electromagnet. The two magnets (Train and Track) repel each other making the trains levitate. The train then travels with only the friction of air.

Four forces of nature• 1) Gravity—force of attraction between objects

with mass.• 2) Magnetism—force of attraction between

opposite poles of a magnet (N and S ) and force of repulsion between like poles of a magnet.(N and N or S and S )

• 3) Weak force—force of attraction between oppositely charged particles (+ and - ) and force of repulsion between like charges (+ and + or – and - )

• 4) Strong Force– nuclear force that holds protons together in nucleus of atoms