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Physics Paper 1, When drawing cells '+' is on the big side (left…

- - - - Static Electricity
        
        When insulating materials rub against each other, they may become electrically charged.
        
        Electrons, are ‘rubbed off’ one material and on to the other.
        
        The material that gains electrons becomes negatively charged.
        
        The material that loses electrons is left with a positive charge.
        
        A polythene rod is rubbed with a duster:
        
        the polythene rod has gained electrons, giving it a negative charge
        
        the duster has lost electrons, giving it a positive charge
        
        An acetate rod is rubbed with the duster:
        
        the acetate rod has lost electrons, giving it a positive charge
        
        the duster has gained electrons, giving it a negative charge
        
        Both the rods and the duster are made of insulating materials. Insulators prevent the electrons from moving and the charge remains static.
        
        Conductors, on the other hand, cannot hold the charge, as the electrons can move through them.
        
        If a negatively charged plastic rod is brought near to another negatively charged rod, they will move apart as they repel each other.
        
        If a positively charged rod is brought close to a negatively charged rod, they will pull together as they attract each other.
        
        Electric Fields
        
        All charged objects have an electric field around them, which shows how they will interact with other charged particles.
        
        The closer you get, the stronger the field.
        
        Electric field shapes:
        
        An electric field is a region where charges experience a force.
        
        Fields are usually shown as diagrams with arrows:
        
        The direction of the arrow shows the way a positive charge will be pushed.
        
        The closer together the arrows are, the stronger the field and the greater the force experienced by charges in that field.
        
        This means that the field is stronger closer to the object.
        
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- - - - Equations
        
        Calculating work done:
        
        The work done is the energy that has been transferred from one store to another
        
        The amount of work done when a force acts on a body depends on two things:
        
        the size of the force acting on the object
        
        the distance through which the force causes the body to move in the direction of the force
        
        work done = force × distance
        
        W = F x d
        
        J = N x m
        
        Calculating power:
        
        When work is done on an object, energy is transferred.
        
        The rate at which this energy is transferred is called power.
        
        So the more powerful a device is, the more energy it will transfer each second.
        
        power = work done / time
        
        P = W / t
        
        W = J / s
        
        Energy demands
        
        Nearly everything requires energy and a way to use energy is by transferring it from one energy store to another.
        
        Systems that can store large amounts of energy are
        called energy resources.
        
        The major energy resources available to produce electricity are fossil fuels, nuclear fuel, bio-fuel, wind, hydroelectricity, geothermal, tidal, water waves and the Sun.
        
        Ultimately, all the energy on Earth originally comes from the Sun but has been stored as different energy resources.
        
        Energy is needed in:
        
        homes - for cooking, heating and running appliances
        
        public services, eg schools and hospitals - running machinery and warming rooms
        
        factories and farms - operating heavy-duty machines and production chains
        
        transport - buses, trains, cars and boats all need a fuel source and some trains and trams connect to an electricity supply
        
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- - - - Stable
        
        A nuclei is stable if the number of protons equals the number of neutrons
        
        The further they go away from this 1:1 ratio - the more unstable they are.
        
        Alpha radiation:
        
        Symbol - 'a' or He
        
        Mass: 4
        
        Charge: +2
        
        Speed: Slow
        
        Ionising ability: high
        
        Penetrating power: low
        
        Stopped by: paper
        
        Beta radiation:
        
        Symbol: β or β-
        
        Mass: 1/2000
        
        Charge: -1
        
        Speed: fast
        
        Ionising ability: medium
        
        Penetrating power: medium
        
        Stopped by: aluminium
        
        Gamma radiation:
        
        Symbol: γ
        
        Mass: 0
        
        Charge: 0
        
        Speed: very fast (speed of light)
        
        Ionising ability: 0
        
        Penetrating power: high
        
        Stopped by: lead
        
        Ionising power: means the ability to knock off electrons from other atoms
        
        Penetrating power: ability to pass through objects
        
        Gamma rays singularly is not dangerous as it passes straight through
        
        Lots of them however penetrate our DNA, changes it so it does not stop replicating and causes cancer
        
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- - - - Hazard: Heating of the resistance wire -> Consequence: Burns to the skin -> Control measures: Do not touch the resistance wire whilst the circuit is connected and allow time for the wire to cool.
        
        Required practical - investigate current - voltage graphs
        
        Aim of the experiment:
        
        To investigate the relationship between current and potential difference for a resistor, bulb and diode.
        
        Method:
        
        1) Connect the circuit as shown in the first diagram.
        
        2) Ensure that the power supply is set to zero at the start.
        
        3) Record the reading on the voltmeter and ammeter.
        
        4) Use the variable resistor to alter the potential difference.
        
        5) Record the new readings on the voltmeter and ammeter.
        
        6) Repeat steps three to four, each time increasing the potential difference slightly.
        
        7) Reverse the power supply connections and repeat steps two to six.
        
        8) Plot a graph of current against the potential difference for each component.
        
        9) Repeat the experiment but replace the fixed resistor with a filament bulb.
        
        Semiconductor diode - method:
        
        1) Connect the circuit as shown in the diagram having chosen a suitable protective resistor (between 100 Ω and 500 Ω).
        
        2) Set the variable resistor to give the lowest potential difference and record the readings on the voltmeter and milliammeter.
        
        3) Alter the variable resistor to increase the potential difference by 0.2 V.
        
        4) Record the new readings on the voltmeter and milliammeter.
        
        5) Repeat steps three to four, each time increasing the current slightly.
        
        6) Reverse the power supply connections and repeat steps two to six.
        
        7) Plot a graph of current against potential difference for the diode.
        
        Hazards - Heating of the resistance wire -> Consequence: Burns to the skin -> Control measures: Do not touch the resistance wire whilst the circuit is connected and allow time for the wire to cool.
        
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