Term
What is electrical energy? |
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Definition
Energy transfer due to an electric current. |
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Term
Why is electricity so useful? |
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Definition
It can be converted into almost any other type of energy. |
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Term
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Definition
The flow of electrons round a circuit |
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Term
What do you need for a current to flow? |
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Definition
A complete circuit Power Source (Battery)
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Term
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Definition
In amps, using an ammeter |
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Term
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Definition
Opposition to the drive of charge. |
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Term
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Definition
The energy used to move charges around. Like "Electrical pressure" Voltage = Current x Resistance. |
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Term
How can the current in a circuit be changed? |
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Definition
If you increase the voltage, the current goes up. If you increase the resistance, the current goes down.
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Term
| How do we measure the power of devices? What is it? |
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Definition
Power (in Watts, W) = energy transferred (in Joules, J) / Time taken (In seconds, S). This power is the rate of energy transfer 1 Watt = 1 J/s 1 Kilowatt = 1000 watts. |
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Term
How can we work out the energy supplied to a device? |
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Definition
Energy transferred (kW h, Kilowatt-hours) = Power of device (kW) x Time in use (hours, h) |
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Term
How can we use kW h to calculate the cost of electricity? |
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Definition
Total cost = number of kW h used x cost per kW h |
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Term
What is the national grid? |
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Definition
A network of cables connecting power stations to homes and other buildings. |
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Term
Why does the national grid need transformers? |
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Definition
Transmitting electricity at a high voltage reduces power loss making it more efficient. We use step-up transformers to step this voltage up to the grid voltage. We use step-down transformers at local substations to step the grid voltage down to 230 volts for use in homes and offices. |
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Term
Why does increasing the voltage reduce wasted energy? |
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Definition
To transmit a lot of electrical power you need a high voltage or a high current because Power = Current X Voltage. However, when we increase the current then the cables become very hot which is a waste of energy. Therefore it is cheaper to increase the voltage. |
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Term
| How do we work out electrical power? |
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Definition
| Power (W) = Current (Amps) x Voltage |
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