50 terms

Electricity and Magnetism Ch. 1 / Reynolds

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law of electric charges
the law that states that like charges repel and opposite charges attract
electric force
the force of attraction or repulsion on a charged particle that is due to an electric field
electric field
the space around a charged object in which another charged object experiences an electric force
electric conductor
a material in which charges can move freely
electric insulator
a material in which charges cannot move freely
static electricity
electric charge at rest, generally produced by friction or induction
electric discharge
the release of electricity stored in a source
electric current
the rate at which charges pass through a given point, measured in amperes
voltage
the potential difference between two points, measured in volts
resistance
the opposition presented to the current by a material or device
cell
a device that produces an electric current by converting chemical or radiant energy into electrical energy
thermocouple
device that converts thermal energy into electrical energy
photocell
a device that converts light energy into electrical energy
electric power
the rate at which electric energy is converted into other forms of energy
series circuit
circuit in which the parts are joined one after another such that the current in each part is the same
parallel circuit
a circuit in which the parts are joined in branches such that the potential difference across each part is the same
Charges flow easily in an?
electric conductior
lightning is a form of?
electric discharge
a _____________ converts chemical energy into electrical energy.
cell
_____________ is the opposition to the current by a material.
resistance
_________________ is the rate at which electrical energy is converted into other forms of energy.
electric power
Each load in a ___________ has the same current.
series circuit
what charges might two objects that repel each other have?
positive and positive or negative and negative
which device converts chemical energy into electrical energy?
cell
which wire has the lowest resistance?
a long, thin metal wire
an object becomes charged when the atoms in the object gain or lose?
electrons
a device that will not protect you from from an electrical fire
electric meter
for a cell to produce a current, the electrodes of the cell must?
have a potential difference
The outlets in your home provide?
alternating currents
Describe how a switch controls a circuit
A switch is used to open and close a circuit. It's made of two pieces of conducting material, one of which can be moved. for charges to flow, the switch must be closed, if it is open the loop in the circuit is broken. This causes the charges to stop flowing.
Name and explain the two factors that affect the strength of electric force.
One factor is the strength of an electric force on each charge, the greater the charge, the greater the force. Factor two is the distance between the charges, the closer the charges the stronger the force.
how do direct and alternating currents differ?
in an alternating current the charges flow in a back and forth motion. In a direct current the charges flowing in one direction.
As resistance goes up, what happens to the current?
it goes down
three basic parts of a circuit
energy sources, wires, and loads
letter used to represent resistance in an equation
R
what happens to the electric current if voltage becomes larger?
the current increases
letter used to represent voltage in an equation
V
letter used to represent current in equations
l
example of a conductor
copper
example of an insulator
glass
friction
happens when electrons are wiped from one object to another
conduction
happens when electrons move from one to another through direct contact
induction
happens when charges in an uncharged metal object are rearranged without direct contact with a charged object
Electrolyte
mixture of chemicals that cells contain
superconductors
a state in which certain materials are cool, to a very low temperature, resistance
how the three parts of a circuit work
the energy source is where the energy is coming from, such as a battery or a nuclear power plant. wires connect the circuit, these wires can be made up of low resistance copper. Loads are what is using the energy, such as light bulbs televisions, and microwaves.
How fuses and circuit breakers protect your home against electrical fires
they stop the current if it is too high, and charges stop flowing, so they don't catch on fire.
factors that affect the resistance of an object
thickness, length, and temperature
two examples of static electricity
example #1 - clothes in the dryer, the particles are being charged by friction as they rub together. as the clothes tumble, negative charges are lost. After you take them out, the transfer of charges has stopped, creating a build up of electric charges on one piece of clothing.

example #2 - when you rub a balloon on your head, you are charging the particles inside the balloon. when you pull it away from your head, it sticks because of static electricity
two examples of electric discharge
example #1 - wearing rubber soled boots, and walking on carpet. negative charges are created and when you reach for a doorknob those negative charges jump out, creating an electric shock or discharge.

example #2 - during a thunderstorm, water droplets, ice, and air move inside the storm cloud. this may cause negative charges to build up at the bottom of the cloud, and positive at the top. the negative charge at the bottom may induce a positive on the ground. this causes lightning, a form of electric discharge.