<p> ELECTRICITY AND MAGNETISM</p><p>PHYSICS IS PHUN - January 2005</p><p>Welcome and Thanks Comment: Basic ideas in electricity and magnetism Review fundamental laws of Electricity and Magnetism summarized in Maxwell’s equations</p><p>STATIC ELECTRICITY</p><p>S All of you have played around with static electricity (E1-1.1) Comment: Origin of electricity is atomic: positive nucleus with protons and neutrons electrons surrounding nucleus atoms are neutral - same number of p’s and e’s</p><p>Neutrons are neutral - effect mass of atom but less effect on chemical properties</p><p>S Pity the poor neutron……(A1-1.83)</p><p>Separation of charges by “friction” actually CONTACT - “triboelectric” effect</p><p>S Compare triboelectric effect with siphon (E1-3.6) Comment: Actually quantum mechanical “tunneling” </p><p>D J1-01 TRIBOELECTRICITY - CHARGING BY FRICTION Charge electrometer with glass rod (+) and with hard rubber rod (-) Examples: shoes on rug, woolen coat on plastic car seat</p><p>S Another example (E1-1.2)</p><p>CHARGING BY CONDUCTION AND INDUCTION</p><p>S Charging by induction (leave slide on during demo) (E1-3.5) D J1-12 INDUCTION - ELECTROSCOPE Charge by induction and check by bringing glass rod close</p><p>D J1-11 ELECTROPHORUS (page 2)</p><p>POLARIZATION</p><p>D J4-11 POLAR AND NONPOLAR LIQUID</p><p>D J4-12 ELECTROSTATIC FORCE - MOVING LUMBER</p><p>Comment: polarization important in biological phenomena, eg human body, and how microwave oven works</p><p>VAN DE GRAAFF GENERATOR</p><p>D J2-03 VAN DE GRAAFF GENERATOR WITH GROUND SPHERE</p><p>D J2-14 LIGHTNING ROD SIMULATOR</p><p>6S Lightning slide set: (E1-2.5 thru 2.10) Charge separation in clouds - mirror on ground Leader develops Lightning discharges along path of leader Prevent lightning using lightning rod</p><p>MAGNETS</p><p>D J7-01 LODESTONE</p><p>MAGNETIC FORCES</p><p>D TWO BAR MAGNETS ON OVERHEAD PROJECTOR (page 3)</p><p>RELATION BETWEEN ELECTRICITY AND MAGNETISM Summarized in four equations known as “Maxwell’s Equations”</p><p>AMPERE’S LAW Electric currents create magnetic fields</p><p>Shown in pre-show S Right hand rule (E3-1.2) D K1-05 FORCE BETWEEN CURRENT-CARRYING COILS Examples: electromagnets, motors</p><p>LORENTZ FORCE Charges moving in a magnetic field experience an electromagnetic force</p><p>S Left Hand Rule (E3-1.1) D K1-12 CATHODE-RAY TUBE - DEFLECTION BY MAGNET D K1-03 FORCE ON CURRENT IN MAGNETIC FIELD Examples: loud speakers, particle accelerators (cyclotron, synchrotron)</p><p>FARADAY’S LAW OF INDUCTION A changing magnetic field creates an electric field</p><p>D K2-04 FARADAY'S EXPERIMENT - EME SET - 20, 40, 80 TURN COILS D K2-01 EARTH INDUCTOR with red magnet Examples: generators, transformers, dynamic microphone</p><p>LENZ’S LAW Induced magnetic fields act so as to oppose the motion that caused them</p><p>D K2-44 EDDY CURRENT PENDULUM Cool pendulum with LN D K2-42 LENZ'S LAW - MAGNET IN ALUMINUM TUBE S Magnets dropped through tube (E4-2.4) Examples: magnetic damping in balance, speedometer damping (page 4)</p><p>COMPLEX ELECTROMAGNETIC PHENOMENA</p><p>D K2-61 THOMSON'S COIL Student holding down ring Shoot ring - with and without LN Example: magnetic levitation trains</p><p>D K2-62 CAN SMASHER - ELECTROMAGNETIC Give explanation then blast can Example: nuclear fusion reaction “theta pinch”</p><p>S Cyclotron dee blue discharge S Cyclotron ion source red glow PRE-SHOW DEMONSTRATIONS</p><p>I7-21 SUPERCONDUCTIVITY - MAGNET LEVITATION</p><p>J2-02 KELVIN ELECTROSTATIC GENERATOR</p><p>J1-24 ELECTROSTATIC HAIR RAISING J1-25 VAN DE GRAAFF - TRAINED RABBIT</p><p>J3-21 FARADAY CAGE J3-23 FARADAY CAGE - RADIOWAVES</p><p>J5-04 MAGNETS J6-02 ELECTROMAGNET WITH JUNK J6-03 ELECTROMAGNET WITH JUNK - WITHOUT CORE J6-04 LOW POWER - HIGH FORCE ELECTROMAGNET Gaussmeter</p><p>K4-07 BICYCLE GENERATOR</p><p>K4-01 AC/DC GENERATOR K4-02 MAGNETOELECTRIC GENERATOR WITH LAMP K4-03 MAGNETOELECTRIC GENERATOR WITH BELL</p><p>K4-21 ST. LOUIS MOTOR</p><p>K4-41 MOTOR-GENERATOR PAIR One Farad Capacitor</p><p>K1-41 BARLOW'S DISC</p><p>K2-46 MAGNET LEVITATION ABOVE SPINNING DISC</p><p>J7-22 MAGNETIC DOMAINS WITH TV J7-23 MAGNETIC DOMAINS - MODEL J7-24 BARKHAUSEN EFFECT</p>