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52 Cards in this Set
- Front
- Back
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Every Circuit Needs... |
- a power supply ((to provide electrical energy)) - a load or loads ((in which electrical energy is converted into other useful forms of energy)) - a conducting path ((that allows electric charge to flow around the circuit)) |
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What is stored inside batteries (cells)? |
chemical energy |
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What happens inside the battery to create electrical energy? |
the chemical energy is transformed into electrical energy as a chemical reaction takes place inside the battery. |
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How do switches work? |
Pushing a button closes the switch in the circuit. This provides a complete (or closed) circuit through which electric charges, called electrons, can flow. This flow of charge is called an electric current (symbol, I). |
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What measures an electric current? |
Electric current is measured in amperes (A) or amps for short. |
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What is a voltage? |
Voltage is a measure of the electrical energy carried by the charges in a circuit. |
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What is voltage measured in? |
Voltage (V) is measured in volts. |
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What is voltage sometimes referred to? |
Voltage is sometimes referred to as potential difference because it measures the change in the potential, or stored electrical energy of the charges as they move from the start to the end of a circuit. |
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When do electric charges gain electrical energy in a circuit? |
When they pass through the power supply |
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How do we figure out the voltage gain? |
The loss of energy that is transformed to other forms is equal to the energy it gains through the power supply. This means that the voltage gain across the terminals of the power supply is equal to the total voltage drop across the rest of the circuit. |
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What is an electrical load? |
An electrical load is an electrical component or portion of a circuit that consumes electric power. This is opposed to a power source, such as a battery or generator, which produces power. In electric power circuits examples of loads are appliances and lights. The term may also refer to the power consumed by a circuit. |
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Where is the type of electricity transformed? |
Components like light globes in an electrical circuit act as loads. It is in each of the loads that the electrical energy carried by the charges is transformed into other forms. In the example of a light globe, electrical energy is transformed into light |
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What does resistance measure? |
Resistance (R) is a measure of how much a load restricts and reduces the flow of current. |
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What is Resistance Measured in? |
Resistance is measured in ohms (Ω). |
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What is an advantage of using a series circuit? |
it is less likely to overheat and it is much simpler |
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What is an advantage of parallel circuit? |
if one blows the others still work |
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What type of currents do batteries use? |
Batteries provide a direct current (DC), meaning that a constant voltage is supplied causing the current to flow in one direction in a circuit. In a DC circuit, electrons carry electrical charge from the negative terminal to the positive terminal of the power source. |
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What do transformers do? |
They increase or decrease the supplied voltage. |
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What do rectifiers do? |
They convert the current from AC to DC |
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What do fuses do? |
if a short circuit occurs, the wires could overheat and cause a fire. Fuses and circuit breakers prevent wiring from overheating due to short circuits or current surges from the mains supply. Fuses are made from a thin wire that heats up quickly when an unusually high current passes through it, causing the fuse wire to melt and break the circuit. |
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What is a short circuit? |
A short circuit occurs when an active wire comes into contact with a neutral wire without passing through a load. |
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What is a safety switch/residual current device? |
a safety switch interrupts the current from the mains supply when there is danger of electric shock. It does this by monitoring the current entering and leaving a building. If the two values are not equal, the safety switch stops the current flow by opening the circuit. |
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Why do most metal appliances have a three pin plug? |
This third pin is connected to the metal casing of the appliance. If a live wire should come into contact with the casing, due to damage to the wiring, current flows directly out of the earth wire to a metal pipe in the ground outside the home.An earth wire prevents electric shock if you touch an electrical appliance with a short circuit. |
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Should we be using incandescent light globes? Why/Why not? |
In incandescent globes, electricity passes through a thin filament, generally made of tungsten metal, causing it to glow white hot. These are relatively inefficient devices for lighting as only 10% of the supplied electrical energy is converted to light; the rest is released as heat. |
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What are the two types of globes we should be using? What are the advantages of them? |
compact fluorescent lamps (CFLs) and light emitting diodes (LEDs) convert more of the electricity energy to light and they last longer |
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How do generators work? |
Generators work on the principle that a coil of wire moving in a magnetic field creates a current of electricity. |
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Name an advantage of coal |
coal is a relatively cheap energy source in Australia and coal reserves are relatively abundant along the eastern seaboard |
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Name a disadvantage of coal |
it isn't renewable, it causes air pollution and thermal pollution |
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What percentage of Australia's energy comes from fossil fuels such as coal, gas and oil? |
90% |
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How does nuclear energy work? |
Nuclear power stations use energy released from the nuclear fission of radioisotopes like uranium to drive turbines that generate electricity in the same way that fossil fuel power plants operate. |
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Give an advantage for nuclear energy |
greenhouse gases are not emitted and nuclear energy does not rely on the combustion of fossil fuels to generate electricity
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Give a disadvantage for nuclear energy |
the nuclear waste produced must be stored for many years which increases risk of nuclear accidents and nuclear energy is not renewable |
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How does hydro-electricity work? |
As water stored in a dam at high elevation falls through pipes, it gains kinetic energy. This kinetic energy is used to turn turbines that generate electricity. |
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What is a disadvantage of hydro-electricity? |
A disadvantage of hydro-electricity is that it involves damming river systems and thus alters ecosystems. |
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What is an advantage of hydro-electricity? |
it does not involve combustion of a fossil fuel and so does not generate greenhouse gases. It is also a renewable energy source. |
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Name an advantage of wind energy |
Wind is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced. |
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Name a disadvantage of wind energy |
Wind farms are noisy and may spoil the view for people living near them. |
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What is biomass? |
Biomass is an energy source that involves burning waste vegetation or burning methane, the biogas produced by the breakdown of organic matter to drive small generators. I |
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Name a disadvantage of biomass |
no harmful emissions, clean energy, abundant and renewable, reduces dependency on fossil fuels, reduces landfills |
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Name an advantage of biomass |
expensive, harmful to environment |
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Name a disadvantage of ocean energy |
expensive |
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Name an advantage of ocean energy |
renewable |
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Name an advantage of geothermal energy |
renewable, safe, clean, simple, reliable and environment friendly |
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Name a disadvantage of geothermal |
expensive, not enough skilled manpower across the globe |
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how does geothermal energy work? |
Geothermal energy from hot rocks involves circulating water via boreholes. The water returns to the surface super-heated then passes through a heat exchanger. Steam produced by the heat exchanger is used to generate electricity in a conventional steam turbine. |
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name a disadvantage of dc |
dc can only power things that only need a little bit of power |
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name a disadvantage of ac |
ac cant be stored as easily |
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What is a solenoid? |
Solenoid A cylindrical coil of wire acting as a magnet when carrying electric current. |
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What is electricity generation? |
electricity generation a device that converts mechanical energy to electrical energy |
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What is an electromagnet? |
An electromagnet is a soft metal core made into a magnet by the passage of electric current through a coil surrounding it. |
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What is electricity? |
electricity is the flow of electrons form one place to another |
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What are lodestones (loadstones) |
A rock that possesses magnetic properties and attracts iron; magnetite. |
