Electricity and Magnetism

• Ferrous Materials - Attracted by a magnet and can be magnetized.


  E.g. Iron, steel, nickel and cobalt
• Non-ferrous Materials - Not attracted to magnets and cannot be magnetized 


  E.g. Copper, silver, aluminum, wood, and glass
• Electric Field Intensity - force exerted by the field on a unit charge place at a point around another charge.


  E is the electric field intensity in N/C. $E=$$F/q$
• Current - Rate of flow of charges in a conductor 


  l is the current in amperes (A), Q is the charge in Coulombs, t is the time in seconds (s). $l =$$Q/t$
• Ohm's law - Voltage across the resistor is directly proportional to its current. V ⋉ l or:


  $V/l =$$R$where V is the voltage in volts (V), l is the current in amperes (A), R is the resistance in ohms (Ω)
• Voltage - Energy per unit charge


  $V =$$Energy/Q$ where Q is in charge of the coulombs (C), V is the voltage in volts (V), Energy is in joules (J)
• E.M.F. (Electromotive Force) - lost volts + terminal potential difference


  $emf =$$IR +$$Ir$ Where, e is the electromotive force (Volts), I = current (A), R = Load resistance, r is the internal resistance of cell measured in ohms.
• Resistance and resistivity 


  $p =$$RA/l$ Where ρ is the resistivity, R is the resistance, l is the length of the material and A is the area of cross-section.
• parallel circuit - the voltage stays the same and current divides
• series circuit - the current stays the same and the voltage divides
• Resistance in Series: $R=$$R₁+$$R₂+$$R₃$
• Resistance in Parallel: $1/R=$$1/R₁+$$1/R₂+$$1/R₃$
• Power: $P =$$Energy/time$ where P is the power in watts (W), energy is in joules (J)
• magnet


  any material that attracts iron and material that contains iron
• magnetism


  force of attraction or repulsion of magnetic materials. Physical property
• magnetic pole


  all magnets, no matter its shape or size have two ends called...
• alike poles


  repel
• unlike poles


  attract
• magnetic field


  area of magnetic force around a magnet. The reason why magnets attract without even touching
• What happens when you break a magnet?

  each piece will have its own north and south pole
• where is the magnetic north pole?

  Northern Canada
• why does a compass act as it does?


  The Earth is a giant magnet with north and south magnetic poles and a magnetic field surround it
• electromagnetism


  relationship between electricity and magnetism
• what happens when a wire is placed in a magnetic field?

  electrical energy is transformed into mechanical energy (this is how the first motor was made)
• what kind of energy is associated with electric circuits?

  electrical energy
• electric force


  attraction or repulsion between electric charges
• electric field


  region around a charged object where the object's electric force is exerted on other charged objects
• static electricity


  buildup of charges on an object, they do not flow continuously
• friction


  transfer of electrons from one uncharged object to another by rubbing
• conduction


  transfer of electrons from a charged object to another by direct contact
• induction


  movement of electrons to one part of an object that is caused by the electric field of a second object.
• static discharge


  loss of static electricity as electric charges transfer from one object to another until both are neutral
• like electric charges...

  repel each other
• unlike electric charges...

  attract each other
• electric current

  continuous flow of electricity through a circuit
• Where is magnetism strongest on a magnet?

  at its poles
• electric circuit

  complete, unbroken path through which electric charges can flow
• conductor


  material that electric charges can flow easily through, used to carry electric charge
• insulator


  material that electric charges cannot flow easily through, used to stop flow of charges
• voltage


  difference in electrical potential energy between two places in a circuit, that pushes current through a circuit