Science 9 - Chapter 7 Test Flashcards
electrons
negative charge
how is static charge produced?
electron transfer
protons
positive charge
when is an atom neutral
equal number electrons & protons
insulator
electric charges don’t move easily
conductor
electric charges can move more freely
unit of measuring charge
coulomb
static charge/electricity
charges collected & held in one place
static
stationary or not moving
atom structure
centre: nucleus –> neutrons & protons (positive)
first electron/valence ring/shell –> 2 electrons
second electron/valence ring/shell –> 4 electrons
movement in atom
- positive nucleus vibrates but remains in position
- only electrons move in solid material (all solid material charged by transfer of electrons)
electron removed
negative charge taken away
electron added
negative charge increases
when does friction occur?
when objects rub against each other
what does friction result in?
one object losing electrons while other gains electrons. electrons added to neutral objects through friction stay in one place. electrons removed from one location on insulator NOT replaced, only insulators can retain static charge.
free electrons
free to move throughout the conductor
Van de Graff generator
uses friction to produce static charge on metal dome, moving belt produces static charge at base of generator. Belt carries charge to top (where it collects on the dome.)
grounding
allowing charges to flow into earth’s surface
lightning is caused by…?
buildup of static electricity
attraction rules
- opposite charges attract
- like charges repel
- neutral charges attract both negative and positive charges
- two neutrals have no affect
contact forces
only effect objects that they touch
electric force
push/pull between charged objects
example of action-at-a-distance force
action-at-a-distance forces
apply force without touching
increasing charge results in
increased electric force
decreased amount of charge results in…?
decreased electric force
decreased distance between charged objects results in…?
increase of electric force
charging by conduction
charging neutral object by touching charged object, extra electrons spread evenly over entire surface of neutral object.
(no electrons transferred from object, instead, repositions electrons inside of object)
why does a charged balloon stick to the wall?
because a positive charge is induced on the surface of the wall
true or false; most metals are good conductors
true
