National Grid

This lesson covers:

  1. How electricity is generated and transmitted via the national grid
  2. The electric power equation:  P=IV\ P=IV

chemical / electrical / kinetic / magnetic


Fossil fuel and nuclear power stations work by generating thermal energy. This is used to turn water into steam which can then rise and turn turbines. The energy of the moving turbines can be converted to energy, which is finally sent out across the national grid.

kinetic
electrical

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Illustration of a plug representing electricity demand peaks during the day.

Electricity demand varies during the day and generally peaks:

Late in the afternoon

Around midnight

In the early morning

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The formula for electric power is:

power=currentvoltage\text{power}=\frac{\text{current}}{\text{voltage}}

power=voltage×current\text{power}=\text{voltage}\times\text{current}

power=voltagecurrent\text{power}=\frac{\text{voltage}}{\text{current}}

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2 A of current is flowing through a wire at 230 V.


What is the electric power?

460

W

W

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The symbol formula for electric power is:

P=IVP=\frac{I}{V}

P=VIP=\frac{V}{I}

P=IVP=IV

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Illustration of flames representing wasted heat generated by current.

When transmitting electricity, a ________ current generates lots of wasted heat.

high

low

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Step-up transformers are used to:

Decrease the voltage and increase the current

Increase the voltage and current

Decrease the voltage and current

Increase the voltage and decrease the current

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Step-down transformers are used to:

Decrease the voltage and increase the current

Increase the voltage and decrease the current

Decrease the voltage and current

Increase the voltage and current

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Diagram showing how electric power is transmitted from power stations through transformers and pylons to homes.

How electric power gets to our homes


up / down / voltage / current


  1. Electric power is generated at a power station.
  2. Step transformers increase the voltage and decrease the current.
  3. The electric power is transmitted via the national grid at low which minimises power loss. 
  4. Step transformers decrease the voltage and increase the current near our homes.
  5. Electric power is wired into our homes at a voltage that is relatively safe to use.
up
current
down

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