* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Magnetism
Edward Sabine wikipedia , lookup
Geomagnetic storm wikipedia , lookup
Maxwell's equations wikipedia , lookup
Magnetic stripe card wikipedia , lookup
Skin effect wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Friction-plate electromagnetic couplings wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Magnetometer wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Magnetic monopole wikipedia , lookup
Electromotive force wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Electromagnetism wikipedia , lookup
Electric machine wikipedia , lookup
Alternating current wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Electromagnetic field wikipedia , lookup
Lorentz force wikipedia , lookup
Superconducting magnet wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Magnetoreception wikipedia , lookup
Magnetotellurics wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetochemistry wikipedia , lookup
Eddy current wikipedia , lookup
Force between magnets wikipedia , lookup
Electromagnet wikipedia , lookup
Magnetism Just the basics Magnetic Poles • Magnetic poles are LIKE electric charges • Like poles repel and opposite poles attract. • They are caused by the movement of electrons in the atoms of elements Magnetic Poles • The two poles are called NORTH and SOUTH • All magnets are dipolar • This means that EVERY magnet, NO MATTER HOW SMALL, has both a north pole and a south pole Magnetic monopoles do not exist! • If I have a magnet, it has a north and south pole • If I cut the magnet in half… Each half will STILL have both a north and a south pole Magnetic Fields • Magnetic fields are VERY similar to electric fields and we draw them the same way. Magnetic Fields • Magnetic field lines are drawn to point away from north and toward south • The symbol for magnetic field strength is B • The unit magnetic field strength is measured in is the Tesla (T) Electricity and Magnetism • Hans Christian Oersted discovered that ANY time there is an electric current (a moving electron) there is a magnetic field produced. • That magnetic field is perpendicular to the current. First Right Hand Rule • This rule helps us find the direction of the magnetic field around a wire with current flowing through it. • Use your right hand – Point your thumb in the Direction of the CONVENTIONAL CURRENT. – The magnetic field wraps around The wire in the direction your Fingers curl. Example Second Right Hand Rule • This rule is used to find the polarity of an electromagnet • Using your Right Hand – Curl your fingers in the direction of the conventional current and your thumb will be pointing in the direction of the north pole Michael Faraday • Faraday discovered that when a current carrying wire is placed inside a magnetic field, the magnetic field will cause a force to be applied to the wire. • The direction of this force can be found by yet another right hand rule Third Right Hand Rule • Used to find the direction of the FORCE acting on a current carrying wire in a magnetic field • Using the right hand – Point your thumb in the direction of the conventional current and your index finger in the direction of magnetic field. The force will be in a direction OUT of your palm. Electromagnetic Induction • Oersted discovered that an electric current causes a magnetic field. • Faraday discovered that if a wire is moved while in a magnetic field, then the magnetic field will cause (induce) an electric current. • This is how electric generators work – Most of the time however, we move the magnet instead of the wire – It is also how microphones and speakers work Alternating Current • When a magnet is spun inside of a coil of wire in a generator, the direction of the north and south pole is continuously changing. • This causes the direction of the current induced in the wire to change • This is called alternating current (A/C) Electric Transformers • Transformers are devices that use electromagnetic induction to increase or decrease the voltage in a circuit. • How much the voltage is stepped up or down depends on the number of coils on each side Calculating Voltage of a Transformer • The voltage in the primary and secondary coils have the same ratio as the number of turns in the coils • Use the following equation Example 1 • What is the resulting voltage in the secondary coil of 40 turns if the primary coil has 20 turns and a voltage of 60V? Example 2 • I have a circuit with a voltage of 120 V. If I wrap this wire around an iron core 3000 times, how many times will I need to wrap a second wire to produce a voltage of only 6 V?