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Electricity - Coggle Diagram
Electricity
The National Grid
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The electricity may be produced by a conventional power station turning a generator or by another method
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A step-up transformer is used to increase the voltage and reduce the current. Less current means less energy dissipated through heating the wire
A step-down transformer is used to reduce the voltage from the transmission voltage to a safer voltage of 230 V for home use
A low resistance and a low current means that the transmission wires will not heat up as much. As a result, most of the power is delivered to the consumer, meaning that less energy is lost through the wires
Transmission Lines
As the electric current flows through the thick cables held up by pylons, they get hotter and dissipate the energy to the surroundings
Static
When insulating materials run against each other, they may become electrically charged
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Polythene Rod and Duster
The polythene rod has gained electrons, giving it a negative charge
The duster has lost electrons, giving it a positive charge
Acetate Rod and Duster
The acetate rod has lost electrons, giving it a positive charge
The duster has gained electrons, giving it a negative charge
Both rods and dusters are made from insulating materials. Insulators prevent the electrons from moving and the charge remains static. Conductors, on the other hand, cannot hold the charge, as the electrons can move through them
If a negatively charged plastic rod is brought near to another negatively charged rod, they will move apart as they repel each other
If a positively charged rod is brought near to a negatively charged rod, they will pull together as they attract each other
Specific Heat Capacity
The specific heat capacity of a material is the energy required to raise one kilogram of the material by one degree celsius
When materials are heated, the molecules gain kinetic energy and start moving faster
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The amount of energy that is required to change the temperature of a material depends on the specific heat capacity of the material
The amount of thermal energy stored or released as the temperature of a system changes can be calculated by using the calculation:
Change in thermal energy (Joules) = Mass (Kg) x Specific heat capacity (Joules per kilogram per degree celsius) x Temperature change (Degrees celsius)
Required Practical
- Place the heater into the central hole at the top of the metal block
- Connect a voltmeter, ammeter, and a battery pack
- Place the thermometer into the smaller hole
- Insulate the block by wrapping it with cotton wool
- Record the temperature of the block
- Record the potential difference, current, and time
- Connect the heater to the power supply and turn it off after 10 minutes
- Record the highest temperature that it reaches and calculate the temperature rise during the experiment
- Record the results in a suitable table
Latent Heat
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The energy required for a change in temperature is given by the specific heat capacity:
E = m x c x change in T
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The horizontal lines show the latent heat of fusion and the latent heat of vaporisation. This is where the molecules are breaking bonds, which is why there is no change in temperature
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At the melting point, latent heat of fusion takes place
At the boiling point, latent heat of vaporisation takes place
Plugs
Earthing Wire
The earth wire is connected to the case and is attached to a metal plate or water pipe underground. As the wire is made of copper, the earth wire provides a low resistance path to the ground. If there is a fault, the live current passing through the ase will follow this path to the ground instead of passing through a person. It is coated in stripped plastic
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Neutral Wire
A copper wire that is coated in blue plastic that also connects to the cable in the wall and completes the circuit
Outer Insulation
All three wires in the cable are bundled together and there is extra plastic insulation wrapped around all of them for safety
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Fields
All charged objects have an electric field around them, which shows how they will interact with other charged particles
The closer you get, the stronger the field
An electric field is a region where charges experience a force. The fields are usually shown as diagrams with arrows
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The closer together the arrows are, the stronger the field and the greater the force experienced by charges in that field. This means that the field is stronger closer to the object
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Mains Electricity
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Fuse
A high current will cause the fuse to melt. The circuit is broken and no more current flows through the device. This means that the case of the device is no longer live and there is no more risk of electrocution