the buildup of electric charges on an object is called a _________ charge
static
two objects will attract one another when they have ___________ charges
opposite
one example of a good conductor is _______
copper
the steady flow of electrons through a conductor is an electric _____________
current
when the resistance in an electrical circuit increases, the current flowing in the circuit _________
decreases
resistance is measured in a unit called the ____
ohms
a path created for a current that allows only one route for the current is called a __________ current
series
a _________ breaker is a device designed to open an overload circuit and prevent overheating
circuit
electric companies usually sell electrical energy in units of ____
kWh
a circuit that has more than two or more separate paths for electrons to follow is a(n) ___________ circuit
parallel
the south pole of a magnet attracts the ______ pole of another magnet
north
when you break an iron magnet into two pieces, you get two ____________
magnets
the region around a magnet where the magnetic forces act is the ________________
magnetic field
the magnetic field of a magnet is strongest at the ________
poles
an electromagnet is only operating when the current is ___
on
the function of an electric motor is to change ____________ energy to _____________ energy
electrical; mechanical
a current carrying wire wrapped around an iron ore is called a(n) _______________
electromagnet
current that does NOT reverse direction is called _______________________
direct current
a simple complete circuit must have wires connected to a __________ and an ___________________
load; energy source
when you walk across a carpeted floor and then touch a metal doorknob, the "shock" you may feel occurs because of a(n) static _____________
discharge
when you rub a balloon on your hair, __________ go from your hair to the balloon
electrons
in a battery, electrons flow from the _________ terminal to the ___________ terminal
negative; positive
a wire that is long and _________ would have the greatest electrical resistance
thin
two identical balloons are both rubbed with wool. If the balloons are brought near each other, they will ________ each other
repel
the core of an electromagnet is usually made of ______
iron
a magnetic field exists around a wire whenever a ________ flows through the wire
current
earth's magnetic field is called the _________________
magnetosphere
List and describe the three essential parts of a circuit
1) wires- conducts current
2) energy source- supplies charge
3) load- uses electrical energy
describe how direct current differs from alternating current
direct currents- only travels in one direction
alternating currents- switches directions
how does lightning form?
1) charges build up in clouds
2) cloud charges are attracted to opposite charges on the ground
3) when imbalance of charges become too great, you get a discharge = lightning