Current Electricity Flashcards
what is an ammeter?
A machine that measures current, must be placed in series
what is voltmeter?
A machine that measures potential difference/voltage, must be placed in parallel
what is an ohmmeter?
A machine that measures resistance, must be placed in parallel
what is a parallel circuit?
A circuit in which the loads are connected by branches so that there are more than one path for the electrons to flow
what is a series circuit?
A circuit in which the loads are connected end to end so that there is only one path for electrons to flow
what is a load?
A device that uses electrical energy by converting it to a different form, (light bulb, heating cell, motor)
what a source?
A device that energizes electrons, (cell/battery)
what is current/amps?
The number of electrons flowing past a certain point every second, the current is measured in the unit amps.
what is voltage/volts?
The difference in the amount of potential energy between 2 points in the circuit, also called the potential difference, measured in volts
what is resistance?
The ability of a material to oppose the flow of electric current, measured in ohms
what is electricity?
a form of energy produced from a variety of non-renewable and renewable sources
what is a connector?
an object that provides a pathway for electrons to flow, (wires)
what is a control device?
a device that controls the electric current by turning it on or off, (switch, circuit breaker)
when was electricity invented? by who?
in 1831 by Michael Farrady and Joseph Fram
what is a conductor?
something that allows electricity to flow through it
what is an insulator?
something that doesn’t allow electricity to flow through it
what is a resistor?
something that resists the flow of electricity
what does AC stand for?
altering current, it is found in motors
what does DC stand for?
direct current, it is found in circuits (battery)
what are the two types of circuits?
series and parallel
what does a cell consist of?
positive and negatives terminals, positive and negative electrodes, and electrolytes
what are the three types of cells?
primary cells, secondary cells, fuel cells
what are some characteristics of primary cells?
non-rechargeable, disposable, 5-year shelf life
what are some characteristics of secondary cells?
rechargeable, disposable, 6 months to one-year shelf life
what are some characteristics of fuel cells?
very long lasting, very expensive, less polluting
what is hydroelectric generation?
uses the flow of water to turn water turbine blades to generate electricity
what are some pros and cons of hydroelectric generation
pros:
- does not pollute air or water
- renewable resource
cons: - uses big volume of water
- disrupts natural flow of water and wildlife
- expensive
- hard to find a location
what is tidal generation?
uses tidal flow to turn water turbine blades to generate electricity
what are some pros and cons of tidal generation?
pros: - renewable resource - does not pollute air or water cons: - can only be built near coastlines - needs big tides
what is wind generation?
uses blowing wind to turn turbines connected to a generator to generate electricity
what are some pros and cons of wind generation?
pros: - cheap, wind is free - can be added or removed easily - no pollution - renewable cons: - wind doesn't flow constantly - noisy - dangerous to birds
what is solar generation?
uses solar panels to collect sunlight to generate electricity
what are some pros and cons of solar generation?
pros: - can be installed anywhere it's sunny - no pollution - renewable cons: - the sun is not always shining - takes up a lot of space - only 20% efficient - expensive
what are the different types of thermal generation?
fossil fuels, radioactive materials, biomass, geothermal
what fossil fuels are used to generate electricity?
coal, oil and natural gas
what radioactive materials are used to generate electricity?
uranium
what biomass is used to generate electricity?
plant or animal matter
what are some pros and cons of fossil fuels?
pros: - produces a lot of energy cons: - non-renewable - takes a lot of time to form
what are some pros and cons of radioactive materials?
pros: - produces a lot of energy cons: - dangerous - non-renewable
what are some pros and cons of biomass?
pros: - renewable cons: - produces CO2 releases methane gas
what are some pros and cons of geothermal generation?
pros: - produces large amounts of energy cons: - bad for the environment - produces CO2 - non-renewable
what is efficiency?
how well the electrical energy in a device is changed to useful energy by that device, no device is ever 100% efficient
what are the four factors that affect efficiency?
amount of resistance, distance that current flows, friction, materials used in the circuit
what does GRASS stand for?
Given Required Analyze Solve Statement
how do you calculate the percent efficiency?
energy output / energy input x 100 = ____%
what is the energy input?
the amount of energy that goes into an electrical circuit
what is the energy output?
the amount of electricity that is produced by the appliance
energy is always measured in…
joules (J) (ex. energy output = 925J, energy input = 1100J)
the energy input is always ____ than the energy output?
higher
how do you calculate the cost of electricity?
cost = power (kW) x time (hours) x rate (kW *h)
how to do convert watts into kilowatts?
watts divided 1000 = kilowatts
cost of electricity is always measured in…
cents, (ex. 0.03 kW x 7 h x 8.7 cents = 1.827 cents)
what are the four factors that affect resistance?
type of material, thickness of wire, length of wire, temperature
what are some ways to INCREASE resistance?
- connecting more loads in series
- making conductor longer and thinner
- using material with high resistance
- increasing the temp. (summer)
what are some ways to DECREASE resistance?
- connecting less loads in series
- making conductor shorter and thicker
- using material with low resistance
- decreasing the temp. (winter)
what is Ohm’s law?
states that as the potential difference (voltage) increases across a load, the current also increases
the current in a SERIES circuit is the ___ across each load
same, (i total = i1 = i2 = i3…)
the current in a PARALLEL circuit is…
split among the # of loads, (i source = i1 + i2 + i3…)
if all loads are the same, they have the same resistance (i load = i source / # of loads)
the voltage in a SERIES circuit is…
split among the # of loads, (v source = v1 + v2 + v3…)
if all loads are the same then the voltage can be calculated as v load = v source / # of load
the voltage in a PARALLEL circuit is the ___ across each load
same, (v source = v1 = v2 = v3…)
how do you calculate current?
i (current) = q (charge) / t (time)
how do you calculate voltage?
v (voltage) = e (energy) / q (charge)
the resistance in a SERIES circuit ___ if more bulbs are added
increases, (r total = r1 + r2 + r3…)
the resistance in a PARALLEL circuit ___ if more bulbs are added
decreases, (1 / r total = 1 / r1 = 1 / r2 = 1 / r3…)
what are the characteristics of a series circuit?
- voltage splits
- current stays the same
- has more resistance
- lower current total
- if one bulb is removed resistance decreases, current increases, voltage stays the same
what are the characteristics of a parallel circuit?
- voltage stays the same
- current splits
- less resistance
- largest current total
- if one bulb is removed resistance increases, current decreases, voltage stays the same
what is the symbol for current?
I
what is the symbol for voltage?
V
what is the symbol for resistance?
Ω
