electricity&magnets

• Static electricity builds up on insulating materials and often ends with a spark or a shock
• when insulating materials are rubbed together negatively charged electrons will be scraped off and dumped on the other
• The electrons are not free to move in an insulator
• The materials become electrically charged with a positive static charge and a equally negative static charge
• It is always the negative electrons that move
• Statically charged objects exert a force on one another
• two things with opposite electric charges are attracted to each other
• Two things with like electric charges repel eachother
• As electric charge builds on an object the potential difference between the object and the earth increases
• A voltmeter measures the potential difference across two points
• An ammeter measures current flowing through it
• uses of static electricity: photocopiers, reducing dust , electrostatic sprayers(insecticides and paint)
• an electric field is created around any electrically charged object
• The closer to the object you get the stronger the electrical field is
• all magnets produce a magnet field where other magnets experience a force
• magnetic field/ forces is strongest at the poles
• placing two bar magnets near each other create a uniform field where two opposite poles attract
• The three main magnetic elements are iron, nickel and cobalt
• permanent magnets: produce their own magnets all the time
• Induced magnets: only produce magnetic field in another magnetic field
• magnetically soft materials lose their magnetism quickly
• magnetically hard materials lose their magnetism slowly
• a moving charge creates a magnetic field
• when a current carrying conductor is put between magnetic poles, the two magnetic fields interact and a force is exerted on the conductor
• force = currents x resistance x length of wire x potential difference (V)
• a solenoid is a long coil of wire
• electromagnetic induction: the induction of a potential difference in a wire which is experiencing a change in magnetic field