P2 - Electricity Flashcards

1
Q

What is electric current

A

Is a flow of electrical charge

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2
Q

Electrical charge will only flow round a complete circuit if something is

A

Providing the potential difference

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3
Q

What is the potential difference

A

The potential difference is the “ driving force “ that pushes charge around the circuit

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4
Q

What ia resistance

A

Anything thst slows down the flow of charge

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5
Q

The current flowing through a component depends on the potential difference across it and the resistance of the component

A

The greater the resistance across a component, the smaller the current that flows

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6
Q

Components with a fixed resistance are called

A

Ohmic conductors

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7
Q

What is a fixed resistance

A

The resistance of the component doesn’t change with current

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8
Q

Ohmic conductors only have a fixed resistance if the

A

Temperature doesn’t change

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9
Q

Examples of ohmic conductors

A

Wires and resistors

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10
Q

For an ohmic conductor at a fixed temperature , the current flowing

A

Is directly proportional to the potential difference across it

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11
Q

However the resistance of some components does change with current E.g.

A

A diode

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12
Q

The resistance of an LDR changes as the intensity ofmlight changes .In bright light

A

The resistance isnlow and in darkness the resistance is high

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13
Q

What is a thermistor

A

A temperature dependent resistor

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14
Q

What are sensing circuits

A

Can be used to automatically change the pd acroos components depending on changes in the environment

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15
Q

What is a series circuit

A

The components are all connected in a line between the ends of the power supply

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16
Q

In a series circuit . If you remove one component

A

The circuit is broken.All the componennts stop working

17
Q

In a series circuit the same current flows

A

Through all components

18
Q

In a series cirxuit the total potential difference is

A

Shared between all components .If you add up the pd across each component you will get the pd of the power supply

19
Q

In parallel circuits, each component is separately

A

Connected to the ends of the power supply.If you take out one loop, the things in the other loops won’t be affected .This means things in parallel cidxuits can be switched on and off without affecting each other

20
Q

In a parallel circuit , all components get the full

A

Potential difference.Potential difference the same everywhere

21
Q

What is an alternative potential difference

A

Is a potenial difference that is constantly changing direction.It produces an alternating current

22
Q

In an alternating current the current

A

Is also constantly changing dkrection

23
Q

What is the brown wire

A

The live wire

24
Q

What is the live wire

A

The live wire provides the alternating potenital difference from the mains supply

25
Q

What is the green and yellow wire

A

The earth wire

26
Q

What is the earth wire

A

Earth wire is the safety wire.Stops the appliance becoming live.It is connnected to the metal casing of an appliance.If a fault causes the live wire to touch the casing , the current flows away through the earth wire

27
Q

What is the blue wire

A

The neutral wire

28
Q

What is the neutral wire

A

Neutral wire completes the circuit.When the appliance is operating normally , current flows through the live and neutral wire

29
Q

What is the National Grid

A

The national grid is a giant system of cables and transformers that covers the UK.It transfers electrical power from power stations to consumers

30
Q

Step up transformer

A

Increases the voltage and reduces the current

31
Q

Step down Transformer

A

Reduces voltage and increases the current