Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
118 Cards in this Set
- Front
- Back
|
the flow of electrons from one place to another
|
current electricity
|
|
|
two types of electricity
|
currents, static
|
|
|
electricity that flows in only one direction
|
direct current (DC)
|
|
|
electricity that constantly reverses the direction it flows
|
alternating current (AC)
|
|
|
device that converts AC to CD
|
rectifier
|
|
|
why electrons flow
|
because of the attraction and repulsion of electric charges
|
|
|
the force of electron current flow
|
voltage
|
|
|
other names for voltage
|
electric potential or electromotive force
|
|
|
unit of voltage
|
volt
|
|
|
instrument used to measure voltage
|
voltmeter
|
|
|
the rate of electric flow
|
current
|
|
|
unit of current
|
ampere
|
|
|
energy used per unit time
|
power
|
|
|
unit of power
|
watt
|
|
|
formula for power
|
power (P) = voltage (V) x current (I)
|
|
|
determines how much electrical energy a device uses
|
power (voltage x current) and the length of time the device is on
|
|
|
unit for measuring electricity per unit time
|
kilowatt-hour
|
|
|
materials through which current flows easily
|
conductors
|
|
|
materials through which current does not easily flow
|
insulators
|
|
|
materials that are not good conductors or insulators
|
semiconductors
|
|
|
the amount by which an object hinders electron flow
|
resistance
|
|
|
unit of resistance
|
ohm
|
|
|
instrument used to measure resistance
|
ohmmeter
|
|
|
the heat that results from overcoming resistance
|
Joule heat
|
|
|
alloy of nickel, chromium, and iron that has a higher resistance than most metals
|
nichrome
|
|
|
the most important factor affecting the ease of current flow
|
the type of material
|
|
|
other factors that affect resistance
|
the diameter of the conductor, the length of the conductor, temperature
|
|
|
a material that allows current to flow with no resistance
|
superconductor
|
|
|
advantages of superconductors
|
a tiny one can conduct a lot of current, there is no Joule heat, they can be used to make unusually powerful electromagnets
|
|
|
the difficulty in using superconductors more
|
a specific, extremely cold temperature is required for a material to become a superconductor
|
|
|
the temperature at which a material becomes a superconductor
|
critical temperature
|
|
|
Ohm's law
|
voltage (V) = current (I) x resistance (R)
|
|
|
an electrical device designed to add resistance to a circuit
|
resistor
|
|
|
resistors whose level is easily changed
|
variable resistors (rheostats)
|
|
|
the path an electric current follows
|
electric circuit
|
|
|
three parts of an electric circuit
|
source of current, set of conductors, load
|
|
|
the source of current in a circuit
|
battery, generator, or other power source
|
|
|
device that transforms the electric energy into some other useful form of energy
|
load
|
|
|
a circuit that has a complete circle from source, through the load, and back to the source
|
closed circuit
|
|
|
a circuit with a gap
|
open circuit
|
|
|
a device that opens and closes a circuit
|
switch
|
|
|
occurs when current takes a shortcut through a circuit, never going through the load
|
short circuit
|
|
|
why a short circuit is dangerous
|
it increases the current, producing a lot of Joule heat
|
|
|
a narrow strip of metal with a higher resistance than the rest of a circuit
|
fuse
|
|
|
purpose of a fuse
|
if a short circuit is created, the fuse overheats and breaks, opening the circuit before a fire can be caused
|
|
|
an automatic switch that opens a circuit if there is too much current
|
circuit breaker
|
|
|
occurs when too many devices are connected to a single circuit
|
overloaded circuit
|
|
|
connected directly to the earth
|
grounded
|
|
|
a circuit with multiple loads that the current flows through one after the other
|
series circuit
|
|
|
how to measure resistance in a series circuit
|
add the resistance of all the loads
|
|
|
how to measure voltage in a series circuit
|
add the voltages of each load (it is divided among them)
|
|
|
circuit with multiple loads arranged so that they are in separate branches
|
parallel circuit
|
|
|
advantage of a parallel circuit
|
if one load goes out, the others still work
|
|
|
how to measure resistance in a parallel circuit
|
the inverse of resistance equals the sums of the inverses of the resistance in each load
|
|
|
how to measure voltage in a parallel circuit
|
use Ohm's law for the whole circuit or for each part (it's the same in all branches)
|
|
|
the first electric light suitable for household use
|
incandescent lamp
|
|
|
inventor of the incandescent lamp
|
Thomas Edison
|
|
|
thing wire in an incandescent lamp that is heated until it glows
|
filament
|
|
|
the white frosting inside a bulb
|
silica
|
|
|
the gas in a light bulb that makes it last longer
|
halogens (bromine or iodine)
|
|
|
more effective bulbs that produce light by passing a spark through a confined gas
|
electric discharge lamps
|
|
|
common electric discharge lamp
|
fluorescent lamp
|
|
|
coating on inside of a fluorescent bulb
|
phosphor
|
|
|
new design for fluorescent bulb allowing them more uses
|
compact fluorescent lamps (CFLs)
|
|
|
an electric discharge lamp filled with neon instead of mercury
|
neon lamp
|
|
|
color of a neon lamp
|
crimson
|
|
|
semiconductor devices that emit light when a direct current is applied
|
light-emitting diodes (LEDs)
|
|
|
why electricity and magnetism are fundamentally related
|
they both stem from electromagnetic force
|
|
|
a device that converts electricity to motion
|
solenoid
|
|
|
device invented to communicate over long distances using electromagnets
|
telegraph
|
|
|
the switch in a telegraph
|
key
|
|
|
code for talking on the telegraph
|
Morse code
|
|
|
an electrical switch operated by an electromagnet
|
relay
|
|
|
a device that converts pulses of electricity into sound waves
|
loudspeaker
|
|
|
parts of the telephone
|
loudspeaker, microphone
|
|
|
device that converts sound waves to pulses of electricity
|
microphone
|
|
|
most important device for converting electricity into motion
|
electric motor
|
|
|
scientist and theory from which the idea of the electric motor came |
Pierre le Pelerin, theory of perpetual motion |
|
|
basic parts of electric motor |
armature, field magnet, commutator |
|
|
part of the motor that reverses the current in the armature |
commutator |
|
|
part of the motor that contains an electromagnet that can freely rotate |
armature |
|
|
part of the motor that contains a stationary, permanent magnet |
field magnet |
|
|
the cause of the rotation of the armature in a motor |
changing the direction of the current each half-turn |
|
|
the kind of electricity produced by a simple motor |
DC |
|
|
motor that does not have a commutator |
AC motor |
|
|
what replaces the commutator in an AC motor |
slip rings |
|
|
six sources of electricity |
light, friction, chemical reaction, motion in a magnetic field, pressure, heat |
|
|
electricity produced by pressure |
piezoelectricity |
|
|
electricity produced by heat |
thermoelectricity |
|
|
electricity produced by rubbing |
static electricity |
|
|
two ways light produces electricity |
photoelectric effect, photovoltaic effect |
|
|
any device that uses a chemical reaction to produce electricity |
electrochemical cell |
|
|
electrochemical cells which can be recharged |
storage cells |
|
|
electrochemical cells which cannot be recharged |
voltaic cells |
|
|
conductors which move electricity from an electrochemical cell to a load |
terminals |
|
|
negative terminal |
anode |
|
|
positive terminal |
cathode |
|
|
what happens when several cells are joined in a series |
voltage is boosted |
|
|
a group of cells grouped as a single source of electricity |
battery |
|
|
what happens when cells are connected in a parallel arrangement |
current increases |
|
|
showed that electric current can produce mechanical motion |
Hans Christian Oersted |
|
|
showed that mechanical motion can produce electric current (using a magnetic force) |
Michael Faraday |
|
|
the process of converting mechanical motion to electric current |
electromagnetic induction |
|
|
a device that measures small electric currents |
galvanometer |
|
|
ways to increase the strength of an electric current produced electromagnetically |
move the magnet more quickly, increase the strength of the magnet, increase the number of turns of wire in the coil |
|
|
a device that uses electromagnetic induction to produce electricity |
generator |
|
|
basic parts of an AC generator |
armature, field magnet, slip rings |
|
|
small AC generators that recharge the battery of an automobile |
alternator |
|
|
what a DC generator has instead of slip rings |
commutator |
|
|
a generator that produces electricity in a fluid |
magnetohydrodynamic generator (MHD generator) |
|
|
a device that spins at high speed when high-pressure steam passes through it |
steam turbine |
|
|
purpose of a turbine |
to provide motion that can be converted to electricity |
|
|
turbine that moves because of hot gases generated by burning fuel |
gas turbine |
|
|
power plant that uses moving water to produce electricity |
hydroelectric power plant |
|
|
ideas for new energy sources for producing electricity |
wind, sun, nuclear fusion |
|
|
a device that increases or decreases the voltage of AC with electromagnets |
transformer |
|
|
transformer that increases voltage |
step-up transformer |
|
|
transformer that decreases voltage |
step-down tranformer |
