21.3 Paying for Electricity and National Grid Flashcards

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1
Q

Why is electrical energy so useful?

A

Electricity is very useful to us as electrical energy can be easily transferred into other types of energy.

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2
Q

What does the amount of electrical energy transferred by a device depend on?

A

The amount of electrical energy a device transfers depends on how long the appliance is switched on and it’s power.

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3
Q

Define the power of an electrical device.

A

The power of an electrical device is how quickly it transfers energy.
It is measured in watts (W) or kilowatts (kW).

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4
Q

Define the kilowatt-hour - kWh.

A

One kilowatt-hour is the amount of energy transferred when one kW is left on for one hour.

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5
Q

What is the national grid?

A

Cables.
Pylons.
Transformers.

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6
Q

What is the purpose of transformers in the National Grid?

A

Step-up transformers increase and step-down transformers decrease the voltage of mains electricity.

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7
Q

Why do we step-up voltage in the national grid?

A
High voltage (up to 500,000V) in power lines reduces current.
Low current reduces energy losses in the cables.
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8
Q

What is the advantage and disadvantage of underground power cables?

A

Advantage - not damaged by storms and are not unsightly.

Disadvantage - Expensive and take long time to repair.

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