Electricity Flashcards
static electricity (electrostatics)
is a charge that stays on the surface of an object
laws of static charge
1) opposite charges attract
2) like charges repel
3) a charged object attracts an electrically neutral object
3 ways of charging an object
1) friction
2) contact / conduction
3) induction
*electrons only move
Friction
2 different material rubbing together so electrons get transferred
conduction
charging an object by contact
induction
charging an object by not touching it
insulators
is a material that doesn’t allow electrons to pass through ex) wool, cotton, rubber
conductors
is a material that easily allows electrons to pass through ex) metal and solutions containing water
semi - conductors
is a material that conducts electrically fairly well ex)silicon
grounding
easiest way to neutralize a charged object
-electrons travel to the ground
current electrically
works all electrical appliances
- flows through a circuit - if they keep on moving its complete
dry cell
battery
series circuit
1 circuit path, same current flows through all the wires , ex) Christmas lights, if 1 light dies they all go out and if you add more loads it will give off less light
parallel circuit
1+ circuit path, used in schools and homes, looks like a chain, add more loads the light will be the same
voltage (volts)
a measure of how strong the current is in a circuit
measured by voltmeter
electrical Current (amps)
the number of electrons that pass a specific point in the circuit
measured by ammeter
electrical Resistance (ohms)
how strongly an object resists the current
measured by ammeter
connected around load
electrode
positive (cathode) and negative (anthode)w
wires
thin metal that allows electricity to flow through / connectors
electrical cell
device that makes chemical energy into electrical
2 types of electrical cells
primary (batteries) secondary (portable generator)
electroscope
old science machine that detected charges (positive and negative) it can charge by induction and conduction
electrostatics used in industry
photocopies, laser printers, air filters
electrostatics painting
the item being painted has a negative charge, the paint is positive, so the negative and positive charges stick together
AC vs DC circuits
2 types of electrical flow
AC
the electrons flow back and forth
DC
the electrons flow in a single direction
potential difference
is the diff. in the energy that happens between 2 points measured by volts
3 ways to discharge and object
grounding, exposure to air, discharge at 1 point
electricity
the flow of electrical power or charge
Types of energy
thermal, radiant, light, chemical, electrical
ohms law named
George Ohms
Ohms law
defines the relationship with voltage, current, and Resistance
V=IxR
Units in ohms law
current=amps
voltage=volts
Resistance=ohms
electrical resistance
resists the flow of electrons
Resistance makes the molecules and atoms rub together an cause heat
3 ways to cause electrical resistance
1) length of wire - longer the wire the greater the resistance
2) thickness of wire - thinner the wire the greater the resistance
3)kind of metal
Voltmeter
measures potential diff.
-plus and minus wire goes around preferred load
Ammeter
used the same as a voltmeter
-connected right into the circuit/put before preferred load
-in series
-don’t connect to dry cell or outlet because fire
Ohmmeter
- goes around preferred load
-measures electrical resistance
conserving energy
saving energy and is measured in KWH
electrical meters
measures that amount of energy used
-now there are smart meters
time-of-use prices
is when electricity is being used the most a least
what do energy-efficient appliances have?
Energuide
energy star
this label shows that the appliances meet government standard
phantom load
when item is plugged in and not used so energy is wasted
cost of electricity
efficiency = output/input x 100
-the input is usually bigger
Joules –> kilo
divide by 1000
kilo—>joules
multiply by 1000
% of efficiency
measures how good appliances convert electrical energy into useful energy
-usually wasted in the form of heat, sound, vibration
