 Effect static electricity charging  Protons (p + ) › in nucleus (center) of an atom › positively charged  Neutrons (n 0 ) › in nucleus (center) of an atom › neutral (no effect on charge)  Electrons (e - ) › move freely outside of the atom › negatively charged

 Electrical Charge – a force that one charge exerts on another  An amount of static electricity can ignite volatile substances (gasoline)  A large difference in the charges in the air can trigger a lightning.  Opposite charges attract each other › protons are attracted to electrons because they have different electric charges  Like charges repel › one electron would repel another electron because they have the same electric charge.

 Remember, an electron (e-) is free to move but a proton is “locked in” to the nucleus of an atom.  This means that when charging occurs, the electrons either move from one physical body to another, OR are rearranged within an existing body. DON’T FORGET THIS!

 Electrons are opportunistic migrants › for electrons to make a move from the atoms of one material to the atoms of another material, there must be  an energy source  a motive  a low-resistance pathway

 Charged objects (ions) have an unequal number of protons and electrons  Charge is the difference between number of electrons and protons  Coulomb (C) › The charge on a single electron is -1.6 x C › The charge on a single proton is +1.6 x C

 The amount of charge carried by a lightning bolt is estimated at 10 C. What quantity of excess electrons is carried by the lightning bolt? › Answer: 6.25 x electrons

 When one body loses an electron, the other body will gain that electron so that there is a net charge on each body  no electrons are destroyed in the process.

 The farther apart opposite charges are, the weaker the attraction force between them.  The closer the charges get, the stronger the force becomes. › F = force › k c = Coulomb’s constant (9x10 9 Nm 2 /C 2 ) › q 1 = charge of particle 1 › q 2 = charge of particle 2 › r = distance

 One charge of 2.0 C is 1.5 m away from a – 3.0 C charge. Determine the force they exert on each other.  The negative sign just means that one charge is positive, the other is negative, so there is an attractive force between them.

 Two balloons are charged with an identical quantity and type of charge of -6.25x10 -9 C. They are held apart at a separation distance of.617 m. Determine the magnitude of the electrical force of repulsion between them.

 Two balloons with charges of μC and μC attract each other with a force of Newton. Determine the separation distance between the two balloons.

 Textbook problems › Page 689 #21-24

 Any material that does not conduct electricity  store electrons on their surface.  Ex: Plastics, dried wood, glass, fabric, and other non-metals  Metals are CONDUCTORS, and do not store charges (wires in your home,etc)

 Friction  Conduction  Induction

 When 2 uncharged objects come into contact, electrons are stripped from one object onto the other and they receive opposite charges. Usually happens when objects rub together.

 When a charged object touches an uncharged object, some of the charge moves so that both objects have the same charges. The new charge will be weaker than the original one.

 When a charged object approaches, but does not touch an uncharged object, a migration of electrons creates an “apparent” charge on the object even though the net charge remains zero

Charging by Induction: Charged object drives off like charges, leaves charged object with opposite charge

 Field Lines -Invisible lines surrounding a charge manifesting a force.  Number of lines per area represents field strength  As lines diverge, field strength diminishes  More charges means greater number of field lines

 Which region experiences greater electric field strength? › region A  Where is that region near at? › near the charge

 Two point charges of equal magnitudes and opposite signs.  Near the charge the field lines are radial  All lines that emerge will terminate  Emerge on positive charge and terminate on negative.

 Field lines do not cross  Repulsion  Like Charges  For Negative charges, reverse the direction of the field lines.

 Given a positive charge that is 2X that of negative, how will the lines terminate? › Only half the lines that emanate from the positive charge will terminate in negative charge › Rest of lines terminate at infinity.