Grade 9 Science Electricity Terms - Chapter 1 of 3
def: a form of energy that results from the interaction of charged particles, such as electrons or protons
e.g: turning a light switch on to illuminate a light bulb
Static Charge (Static Electricity)
def: an electric charge that tends to stay on the surface of an object, rather than flowing away quickly
e.g: rubbing a balloon on your pants and bringing it close to your hair
Charging by Friction
def: a process in which objects made from different materials rub against each other, producing a net static charge on each
e.g: rubbing your feet across the carpet
def: a list of materials that have been arranged according to their ability to hold on to electrons
e.g: metal would be lower on the series because it is stronger/attracts more electrons, but wood glass would be higher on the scale because it is weaker/lose electrons
def: a material in which electrons cannot move easily from one atom to another
e.g: wood, rubber (any material that is not a metal)
def: a material in which electrons can move easily between atoms
e.g: metals (copper, aluminum)
def: a material in which electrons can move fairly well between atoms
e.g: non-metals, such as silicon
def: an object that can supply a very large number of electrons to, or can remove a very large number of electrons from, a charged object, thus neutralizing the object
e.g: a utility pole has a bare wire running down the outside, connected to the ground, to have a quick way to neutralize an electric charge
def: a device for detecting the presence of an electric charge
e.g: two kinds of electroscopes include: metal leaf electroscopes and pith ball electroscopes
metal leaf electroscope pith ball electroscope
Charging by Contact
def: generating a charge on a neutral object by touching it with a charged object
e.g: when a neutral pith ball is touched by a negative rod, some electrons flow from the rod to the pith ball, causing the pith ball to become negative and the rod to have a reduced charge (still negative though)
Laws of Electric Charges
def: laws that describe how two objects interact electrically when one or both are charged
the 3 laws are:
1. Like charges repel.
2. Opposite charges attract.
3. Charged and neutral objects attract each other.
def: a property of the space around a charged object, where the effect of its charge can be felt by other objects. an electric field produces an electric force on any other objects that are in the field.
Induced Charge Separation
def: the movement of electrons in a substance, caused by the electric field of a nearby charged object, without direct contact between the substance and the object
e.g: when a neutral pith ball is in the electric field of a negatively charged rod, all the electrons in the ball move as far away as possible from the rod, because like charges repel.
def: a charged atom or group of atoms
they are formed when charge is transferred and atoms have either gained or lost one or more electrons
def: a metal sphere or point, attached to the highest part of a building and connected to the ground. an insulated copper wire connects the lightning rod to a bare metal plate or wire in the ground.
important in rural areas, where the highest buildings are houses and barns
e.g: lightning usually strikes the highest point in an area, so tall buildings have lightning rods attached to the roof. when lightning strikes (the lightning rod), the charges move through rod, down the wire, and into the ground, preventing any damage to the building.
def: a type of cleaner that removes unwanted particles and liquid droplets from a flow of gas. invented by Frederick Cottrell in 1907.
e.g: used to reduce pollution from smokestacks
Van de Graaff Generator
def: a device that accumulates and transfers very large charges
they have been used as atom smashers since the 1930's
accelerate particles to very high speeds
new subatomic particles are formed by this process
how it works: the metal sphere rests on an insulated column and is where the charges accumulate. the collecting comb is attached to the inside of the sphere. the charged belt induces a redistribution of charges in the comb, which causes the charges to accumulate on the sphere. the motor drives the lower roller, and as the belt moves over it, it gets charged by friction. the rubber belt runs over two rollers. charges stick to it and are carried up as it rotates.
def: a small device that detects and measures exposure to radiation
e.g: astronauts wear them when they are above Earth's atmosphere, which protects them from radiation emitted by the sun
some are like a photographic film, and others resemble a charged metal leaf electroscope surrounded by gas. in the example of the electroscope, gas would normally be a non-conductor, but radiation knocks electrons from the gas atoms, and causes the gas to become a conductor. there is a charge transfer between the gas and the electroscope.