P5

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  • Created by: Jess
  • Created on: 17-05-13 14:56
What is build up os static caused by?
Build up of static energy is caused by friction, when 2 insulating materials are rubbed off together electrons are scraped off and put on each other. This leaves a positive static charge on 1 material and a negative static charge on the other
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What are positive and negative electrostatic charges produced by?
+ve and -ve electrostatic charges are only produced by the movement of electrons
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What are positive static charges always caused by?
Positive electrostatic charges are always caused by electrons moving away from the material to somewhere else
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What happens when electric charges are opposite to one another?
Opposite electric charges attract each other, and like charges repel each other
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What happens when you rub 2 insulating materials together?
When you rub 2 insulating materials together lots of electrons get put together on one of the insulators, which becomes -vely charged. The electrons try to repel each other but can't move as their positions are fixed, resulting in static electricity
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What annoyances can static electricity cause?
Attracting dust, clinging clothes and crackles, bad hair days
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Why can static electricity give you a bad hair day?
Static electricity builds up in your hair, giving each strand the same charge, which means each strand of hair is repelling each other
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Why can static electricity attract dust to insulating materials?
Dust particles are easily attracted to anything charged, so insulating materials (e.g. glass) get easily charged and attract dust particles
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How does static electricity cause clinging clothes and crackles?
When synthetic materials are dragged over each other electrons gets scraped off leaving static charges on both parts, which leads to attraction so the clothes cling to you and little sparks or crackles are charges rearranging themselves
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What is an electric current?
An electric current is a flow of charge
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In an electrical circuit what are the components full of?
Components in an electrical circuit are full of charges (electrons) that are free to move
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In a complete circuit how do the charges flow round the circuit?
In a complete circuit the battery pushes the free charges around the circuit through the wires, the charge flows all the way round and back to the battery without getting used up or disappearing.
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What does current depend on?
Current will only flow through a component if there's a voltage across the component, and current is slowed down by resistance in the circuit
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What is resistance in an electric circuit caused by?
Resistance is caused by things in the circuit such as components e.g. lamps or thermistors
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What is voltage?
Voltage is the driving force that pushes the current around a circuit
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What happens to the current if you increase voltage?
If you increase voltage then more current will flow
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What happens to the current if you increase resistance?
The more you increase resistance, the less current will flow
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What is power?
Power is the rate of energy transfer, anything that supplies electricity is also supplying energy. Power is usually measured in watts (W)
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What is the equation for Power?
Power (W) = Voltage (V) X Current (A)
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What does it mean for an appliance to have a high power rating?
A high power rating means that the appliance transfers lot of energy in a short time, this means that an appliance with a high power rating will use a high current
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What is potential difference?
Potential difference is the proper name for voltage, and tells you how much energy is transferred to/from each unit of charge as it moves between 2 points
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What is the 'push' that moves the charge round the current?
the battery transfers energy into charge which is the 'push' that moves charge around the circuit
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What do components do to the charge in an electrical circuit?
Components transfer energy away from the charge as it passes through the component, so that it can use the energy e.g. lamp would use energy for light
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Why potential difference a measure of work down on/by a charge?
Potential difference tells you how much energy is transferred between 2 points, which tells you how much work done is done between 2 points
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What does the voltage of a battery tell you?
The voltage of a battery shows you how much work the battery will do to charge that passes through it i.e. how big a push it will give
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Where must a voltmeter always be places in a circuit?
A voltmeter must be placed in parallel with a component so it can compare the energy the charge has before and after passing through the component
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What does the slope of a voltage-current graph show you?
The slope of a voltage-current graph shows resistance, the steeper the slope the lower the resistance
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Why do resistors get hot when current passes through them?
When electrons move through a resistor they collide with stationary positive ions in the resistor. These collisions make the ions vibrate more which causes an increase in temperature
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How does a filament lamp work?
A filament lamp contains a piece of wire with a really high resistance, so when the current passes through it, its temperature increases so much that it glows, because is the light you see
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What happens to the resistance of a LDR when light changes?
The resistance of an LDR in bright light falls, and in darkness the resistance is at its highest
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What happens to the resistance of a thermistor when temperature changes?
A thermistor has a low resistance in hot conditions, and a high resistance in cold conditions
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How are components connected in a series circuit?
In a series circuit the components are connected in a line, end to end, between the positive and negative ends of the power supply
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How is potential difference distributed in a series circuit?
In a series circuit the total potential difference of the supply is shared between the components
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Other cards in this set

Card 2

Front

What are positive and negative electrostatic charges produced by?

Back

+ve and -ve electrostatic charges are only produced by the movement of electrons

Card 3

Front

What are positive static charges always caused by?

Back

Preview of the front of card 3

Card 4

Front

What happens when electric charges are opposite to one another?

Back

Preview of the front of card 4

Card 5

Front

What happens when you rub 2 insulating materials together?

Back

Preview of the front of card 5
View more cards

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