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GCSE Physics > Paper 2 Overview > Flashcards

Paper 2 Overview Flashcards

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1
Q

SP8a - What is work done?

A

The energy transferred by a force as it moves an object in the direction of a force.

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2
Q

SP8a - What is the equation for work done?

A

E = F x d

(Energy = Force x distance moved)

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3
Q

SP8a - What is the equation for Power?

A

P = E ÷ t

(Power = Energy ÷ time)

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4
Q

SP8a - What is the unit for power?

A

W - Watts

(Equivalent to J/s - Joules per second)

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5
Q

SP9a - What do you call forces between objects that are touching?

A

Contact forces

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6
Q

SP9a - What is the name for the regular upward force form the ground when you’re standing?

A

Normal contact force

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7
Q

SP9a - What are the three non-contact forces?

A
  • Gravitational fields
  • Static electricity
  • Magnetism
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8
Q

SP9a - What do all objects that produce a non-contact forces have?

A

A force field.

An area around an object in which another object could experience a force.

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9
Q

SP9a - Describe how the gravitational pull between the earth and the moon are action-reaction forces.

A
  • Force is a vector quantity.
  • The force of the moon on the earth is the same size as the earth on the moon but they are in opposite directions.
  • Neither objects move in the direction of the force.
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10
Q

SP9c - What is the formula for a moment?

A

Moment (N m)

=

Force (N) x distance perpendicular to the pivot (m)

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11
Q

SP9c - What could you say when weights around a pivot are balanced?

A

It is in equilibrium

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12
Q

SP9c - What is the principle of moments?

A

The some of clockwise moments = the sum of anti-clockwise moments

[When a system is in equilibrium]

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13
Q

SP9b - How do you work out the direction and size of the resultant force using the component forces?

A

The Parallelogram method:

  • (If the start of a diagram hasn’t already been provided, draw to the two forces using a scale)
  • Draw another pair of dashed-lines parallel to the forces
  • This should form a parallelogram
  • Draw a line from the object to the vertically opposite corner
  • Measure this line and use the scale to work out the size
  • If required, measure the angle to show the direction
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14
Q

SP9b - How do you resolve the component forces using the resultant force?

A

The Rectangle method:

  • Draw faint horizontal and vertical lines fom the object
  • Measure the angle from the horizontal/vertical that the object is at
  • Using a scale, draw a line the represent this force
  • Draw lines down and across from where this line ends to the horizontal and vertical respectively
  • Measure out the length from the object to each of these poitns
  • Use the scale to work out the size
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15
Q

SP9c - Explain why using two different sized gears in a car may be beneficial.

A
  • The first smaller gear can be connected to the motor where it recieves the moment
  • This passes on an equal force to the second larger gear
  • Since the second gear is larger, it will have a larger radius.
  • This means that its the distance from the pivot will be greate
  • Therefore it will have a larger moment (turnign force) as M = F x d
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16
Q

SP9c - Why is a longer lever more effective?

A
  • The formula for a moment (the turning force) is M = F x d
  • Thus, by increasing the distance form the pivot, you will either:
  1. Increase the turning force
  2. Decrease the force required to produce the same turning force
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17
Q

SP10a - Describe the structure of an atom including features of the sub-atomic particles.

A
  • Proton and neutron in the nucelus, each with a relative mass of 1.
  • Protons have a charge of +1.
  • Electrons orbit in energy levels each with a charge of -1 and a relative mass of 1/1835 (negligible)
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18
Q

SP10a - Descirbe what a potential difference is.

A

The force that pushes the electrons to flow around the circuit.

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19
Q

SP10a - What is conventional current?

A

What we refer to as the direciton of current from positive to negative. Opposite to the flow of electrons.

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20
Q

SP10a - What are the two types of circuits?

A
  • Series: everything connected in one route
  • Parallel: many options for different routes.
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21
Q

SP10a - Why may parallel circuits be more beneficial?

A
  • If the circuit becomes incomplete along one path, the rest of the circuit can still continue to function. (e.g - Switches can be connected to different parts meaning lights in parallel to each other can be switched in and off individually)
  • If a bulb goes off, the rest of the circuit in parallel to this can still continue to function
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22
Q

SP10b - What is the unit for current and how can it be measured?

A

Amps (Amperes). Measured using an ammeter which is attached in series to the circuit

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23
Q

SP10b - What is the unit for potential difference and how can it be measured?

A

Volts. Measured using a voltmeter which is attached in parallel to the component you are measuring the potential difference of.

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24
Q

SP10b - How does total current differ in parallel and series circuits?

A
  • S: The total current is the same at all points throughout the circuit
  • P: The total current gets split between the branches of the circuit, inversely proportionate to the resistance of the components in those branches.
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25
Q

SP10b - How does potential difference differ in parallel and series circuits?

A
  • S: The p.d is different across different components, directly proportionate to the resistance of that component
  • P: The p.d is tha same at all points across the circuit
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26
Q

SP10c - What is current?

A
  • The flow of electrons
  • The rate of flow of charge
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27
Q

SP10c - What is the unit for charge?

A

C - Coulombs

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28
Q

SP10c - What is the equation linking charge and current?

A

Q = I x t

(Charge = Current x time)

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29
Q

SP10c - What equation links energy and charge and how can this be changed to link energy to current?

A

E = Q x V (Energy = Charge x p.d)

since Q = I x t, this means that

E = I x t x V (Energy = Current x time x p.d)

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30
Q

SP10d - What is Ohm’s law?

A

V = I x R

(p.d (V) = Current (A) x Resistance (Ω))

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31
Q

SP10d - What is resistance?

A

The force pushing back against p.d opposing and reducing the current.

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32
Q

SP10d - How do you calculate the resistance in series and parallel circuits?

A
  • Series: Add up the resistance of all the components
  • Parallel: 1/RT = 1/R1 + 1/R2 + ………..
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33
Q

SP10d - What is key to remember about the size of the total resistance in series and parallel and series circuits?

A
  • S: It is greater than any of the individual resistances
  • P: It is smaller than all of the individual resistances
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34
Q

SP10e - What does a IV graph for fixed resistor look like and why?

A
  • It is a straight diagonal line showing direct proportion.
  • This is because resistors are ohmic conductors.
  • The voltage is directly proportionate to the current.
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35
Q

SP10e - What is an ohmic conductor?

A

A component in a circuit that follows Ohm’s rule of V=IxR

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36
Q

SP10e - What does the gradient of an IV graph represent?

A

The inverse of the resistance (1/R)

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37
Q

SP10e - What does a IV graph for diode look like and why?

A
  • A line that is nearly on the x-axis till it shoots up.
  • This is because a diode has an infinitely high resistance till a point where it has an infinitely low resistance
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38
Q

SP10e - What does a IV graph for filament lamp look like and why?

A
  • An S shaped ‘curve’.
  • This is because the resistance of a lamp increases due to the temperature increase as it conducts electricity at a higher voltage
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39
Q

SP10e - Describe what a graph for resistance of a thermistor would look like and why.

A
  • The x-axis would be temperature (°C) and the y-axis would be resistance (Ω)
  • As the temperature increases, the resistance decreases. This forms a negative curve in an L shape
  • This can be used to reduce the current in lower temperatures.
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40
Q

SP10e - Describe what a graph for resistance of an LDR (Light-dependant resistor) would look like and why.

A
  • The x-axis would be light intensity (lux) and the y-axis would be resistance (Ω)
  • As the light intensity increases, the resistance decreases. This forms a negative curve in an L shape
  • This is used for lit up signs outside. In darker conditions (lower light intensity) bulbs don’t need to be as bright.
  • Thus, the resistance is higher to reduce the current and brightness
  • Resistance is high against the dark side #Starwars
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41
Q

SP10e CP - Describe your set-up for an experiment to compare the relationship of V=IxR in a resistor, and a filament lamp in parallel/series.

A
  • Set up a series circuit with a power pack, an ammeter, a fixed resistor and a voltmeter in parallel to this.
  • Provide different voltages from the power pack.
  • For each voltage provided, note down the current - Replace the fixed resistor with a lamp and repeat
  • Set up the circuit from here so that there is a voltmeter attached in parallel to this.
  • Attach another lamp to the circuit with another voltmeter in parallel to this
  • Measure out the voltages and currents when different voltages are supplied
  • Move one of the bulbs with its voltmeter to a new branch forming a parallel circuit
  • Add an ammeter to each branch of the circuit
  • Now measure the voltage and current depending on the voltage provided
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42
Q

SP10f - What is the heating effect?

A
  • The heating effect is when a circuit warms up due to the resistance in its wires.
  • Work is done against the resistance and so energy is transferred.
  • This is in the form of heating and dissipates into the surroundings
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43
Q

SP10f - Where is the heating effect useful?

A
  • In appliances such as electric heaters and kettles where the aim is to use thermal energy, the heating effect is incredibly useful.
  • In these circuits, resistance tends to be high.
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44
Q

SP10f - Describe what resistance is in terms of a metal’s structure.

A
  • Current is the flow of electrons.
  • A metal is made of electrons flowing around positive metal ions
  • When the electrons are moving in the circuit, they can collide into these posistive metal ions.
  • These collisions are resistance and they transfer energy
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45
Q

SP10f - How can resistance be reduced in a circuit?

A
  • Choosing a metal with a lower resistance
  • Using a thicker wire (more space for electrons to flow)
  • Using a shorter wire (less distance in which they can collide)
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46
Q

SP10f - What formula links energy, time and voltage?

A

E = I x t x V

Energy = Current x time x Voltage

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47
Q

SP10g - What are the four formulae for power?

A
  • P = E/t
  • P = I x V
  • P = I² x R
  • P = V² ÷ R
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48
Q

SP10g - How do you form the the equations that link Power and Resistance?

A
  • We know that P = I x V and that V = I x R
  • If we substitue the V in the first equation we get P = I x I x R or P = I² x R
  • If we rearrange V = I x R we get I = V ÷ R
  • So if we substitute this in we get P = V x V ÷ I or P = V² ÷ R
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49
Q

SP10h - What the voltage and frequency of and type of electricity that comes through mains supply?

A
  • 230V
  • 50Hz (changes diretion 50 times per second)
  • a.c
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50
Q

SP10h - What are the differences between d.c and a.c?

A

d.c:

  • Only one direction (positive to negative)
  • Electrons loose energy as they travel from negative to positive
  • A graph showing the direction will only ever be on one side of the x-axis

a.c:

  • Constantly switching direction (this is their frequency)
  • Electrons vibrate and pass on energy
  • A graph showing direction will contantly cross zero and over the x-axis

A̶C̶/̶D̶C̶ ̶a̶r̶e̶ ̶a̶n̶ ̶A̶u̶s̶t̶r̶a̶l̶i̶a̶n̶ ̶r̶o̶c̶k̶ ̶b̶a̶n̶d̶ ̶f̶o̶r̶m̶e̶d̶ ̶i̶n̶ ̶S̶y̶d̶n̶e̶y̶ ̶i̶n̶ ̶1̶9̶7̶3̶ ̶b̶y̶ ̶b̶r̶o̶t̶h̶e̶r̶s̶ ̶M̶a̶l̶c̶o̶l̶m̶ ̶a̶n̶d̶ ̶A̶n̶g̶u̶s̶ ̶Y̶o̶u̶n̶g̶.̶

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51
Q

SP10i - Describe the five features of a 3-pin plug.

A
  • Live wire: Connects the appliance to the generators at the power station providing 230V
  • Neutral wire: The return path to the power station and will be at 0V if circuit is correctly connected
  • Earth wire: Connects the metal parts of the appliance to a large spike of metal that pushes down and connects to the ground. Will be at 0V unless the circuit is incorrectly connected
  • Fuse: A Safety device usually 3, 5 or 13 A
  • Plastic casing: This electrical insulator allows you to safely hold the plug
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52
Q

SP10i - How does an earth wire make an appliance safer?

A
  • If a wire comes loose and touches the metal part of the appliance, the electricity will beable to flow through this.
  • When a person touches it, the electricity can pass through the person to the ground.
  • This would give them an electric shock.
  • However the earth wire provides an easier way to travel to the ground.
  • As electrcity always takes the past of least resistance, it goes this way and the person doesn’t get an electric shock
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53
Q

SP10i - How does a fuse provide safety? (Describe this though it’s structure)

A
  • A fuse is a glass tubing with a thin metal wiring that the electricity passes through.
  • A faulty appliance may draw too much current which would heat up and cause a fire.
  • However depending on the value of the fuse, it will melt once the current has reached a certain level and cause the circuit to be incomplete meaning current stops flowing through it
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54
Q

SP10i - How do you choose the best value for a fuse?

A
  • Fuses are typically found in 3A, 5A, and 13A.
  • You want to pick one that has a current higher than what the current of the appliance is but not to high.
  • This way it will stop a fualty appliance but not a properly functioning one.
  • If an appliance has a current of 3A, you would pick a 5A fuse. 3A would be too low and 13A would be too high
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55
Q

SP10i - What are circuit breakers and how do they work?

A
  • Circuit breakers are automatic swtiches that detect a rise in current and automatically switch off the supply safely.
  • They are an alternate to fuses.
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56
Q

SP10i - Why are circuit breakers more advantageous than fuses?

A
  • They can just be turned back on rather than having to buy a new fuse
  • They work quicker.
  • You elliminate the risk of an accident occuring while the fuse is melting
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57
Q

SP10i - What are the colours of the earth, neutral and live wires?

A
  • Earth wire: Green and yellow
  • Neutral wire: Blue
  • Live wire: Brown
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58
Q

SP10i - Why may fuses be more advantageous than circuit breakers?

A
  • Fuses are cheaper
  • More practical for small scale uses (e.g. small appliances)
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59
Q

SP11a - Describe the movement of electrons and the charges involved when you rub an acetate rod with a cloth.

A
  • Both objects start off as neutral.
  • Electrons move from the acetate rod to the cloth so the acetate rod ends up positive and the cloth ends up negative.
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60
Q

SP11a - Describe the movement of electrons and the charges involved when you rub an polythene rod with a cloth.

A
  • Both objects start off as neutral.
  • Electrons move to the polythene rod from the cloth so the polythene rod ends up negative and the cloth ends up positive.
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61
Q

SP11a - Describe what will happen when you hang two rods next to each other with:

  • Positive and positive charges
  • Positive and negative charges
  • Negative and negative charges
A
  • Repel
  • Attract
  • Repel
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62
Q

SP11a - Explain how charging with induction works. (Use a balloon a jumper and a wall as an example)

A
  • If you rub a balloon against a jumper, the friction causes electrons to transfer from the jumper to the balloon.
  • The balloon now has a negative charge
  • When brought close to a wall, the negative charge of the balloon repels the electrons in the wall
  • The protons are brought closer to the surface of the wall as they are attracted to the balloons negative charge
  • The balloon is attracted to the positive charge on the surface of the wall causing it to stick
  • The wall has an induced charge
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63
Q

SP11b - How might you become charged while walking along a carpet?

A

Friction between your feet and the floor and slight friction between you and the air builds up charges.

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64
Q

SP11b - After gathering charge, how may you become discharged?

A
  • By touching something made of conducting material, the electrons will jump to the object and head to the ground.
  • You may experience a small electric shock
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65
Q

SP11b - Explain how lightning occurs.

A
  • Static electricity builds up in clouds due to friction between ice and water particles in air currents.
  • The negatively charged particle move towards the bottom of the cloud.
  • As the ground is neutral, it is relatively positive to the cloud and so when the charge in the clouds is too great, they jump to the ground to discharge.
  • This produces a spark which is lightning.
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66
Q

SP11b - How may a tall building protects an area from lightning.

A
  • A tall building may install a lightning conductor.
  • This would be a metal structure that would be the tallest structure in an area that runs through the centre of the building to the ground.
  • This means that a cloud will discharge through this which wont affect the surrounding areas.
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67
Q

SP11b - Explain the safety feature that protects airline tankers and aircrafts.

A
  • As high amounts of fuel pass through the nozzle at a fast rate, this build up friction which charges the fuel droplets.
  • Once they have built up a great charge they want to discharge.
  • This would create a spark which would light the fuel causing an explosion.
  • The bonding line is attached which earths the aircraft so that the charge flows through easily to the ground without any spark.
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68
Q

SP11b - Why don’t cars need a bonding line at petrol stations.

A

The pipes and the car’s tyres earth the car already.

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69
Q

SP11b - Name some uses of static electricity.

A
  • Electrostatic sprays:
    • Spray paint
    • Pesticide
  • Printers
  • Electrostatic precipitators
70
Q

SP11b - How do electrostatic sprays work?

A

The nozzle contains electrodes which negatively charge the spray droplets. This leads to two things:

  1. The like charge between all droplets spread them out
  2. The negative charge attracts to the relatively positive object/crop and then charges it by induction to stick
71
Q

SP11b - Name some advantages of electrostatic sprays

A
  • Since they spread out there is wide coverage
  • Since they attach through static induction there is even coverage
  • Since all the droplets attach, less spray is wasted
72
Q

SP11c - What is a force field, and what is an electrostatic field?

A
  • A force field is the area around an object in which an object will experience a force and so…
  • An electrostatic field is the area around an object where a charged object will experience a force
73
Q

SP11c - What does a negative and a positive point charge diagram look like

A
  • Both are a dot with equally spaced lines originating form the centre.
  • In a positive one there are arrows away and in a negative one they are towards
74
Q

SP11c - What will be the difference between two field diagrams if one has a stronger charge

A

There will be more lines as they will be closer together

75
Q

SP11c - How do you know where the field is strongest?

A

Where the lines are closest together

76
Q

SP11c - What are the four rules about field lines?

A
  • Lines never cross
  • The closer the lines are is where the field is strongest
  • Start on the positive charge and end on the negative charge
  • Shows the direction of force on an object
77
Q

SP11c - What do two oppositely charged parallel plates form?

A

A uniform parallel electrostatic field

78
Q

SP11c - If an alpha particle is placed into a uniform parallel field where will it move?

A

Towards the negatively charged plate.

79
Q

SP13a - Explain how a loop of wire can gain an induced current using a magnet.

A
  • A magnet has a magnetic field around it.
  • Once it moves throughout the wire, the field induces a P.d. in the wire which creates a magnetic field opposite to original change.
80
Q

SP13a - How does an alternator work?

A
  • A coil of wire wrapped around an iron core is rotated inside a magnetic field
  • Wires from the coil are connected to slip rings on the axle of the coil
  • The slip rings make electrical contact through carbon brushes
  • This produces an alternating current
81
Q

SP13a - How does a dynamo work?

A

Same concept as an alternator except:

  • The wires are connected to a split ring commutator
  • The commutator is connected to the carbon brushes
  • Every half-turn the connections are swapped
  • Thus, this produces a direct current
82
Q

SP13a - How do microphones work?

A
  • (The opposite to loudspeakers)
  • Sound waves cause vibrations in air pressure
  • The pressure causes a diaphragm to move back and forth
  • The diaphragm moves a coil of wire back and forth
  • This causes the coil which is wrapped around a permanent magnet to gain an induced voltage and current
  • The amplitude of the wave affects the volume
  • The frequency affects the pitch
  • Converting sound energy into electrical energy
83
Q

SP13a - How do loudspeakers work?

A
  • (The opposite to microphones)
  • An a.c. voltage passes througha coil
  • This moves the coil along a permanent magnet
  • The coil hits the diaphram causing it to vibrate
  • This creates soundwaves
  • The higher the current, the larger the frequency and amplitude
  • And so the volume and pitch is higher
  • Converting electrical energy into sound energy
84
Q

SP13b - What is the national grid?

A

The system that connects power stations to homes to provide electricity nationally

85
Q

SP13b - What are transformers, both step-up and step-down?

A

Transformers are (not robots in disguise) devices that alter the voltage and current of electricity.

  • SU increase voltage; decrease current
  • SD decrease voltage; increase current
86
Q

SP13b - Describe the process of transferring energy from power stations to houses and factories.

A
  • Electricity is generated at the power station (11kV)
  • Stepped up (400kV) for transmission lines
  • Stepped down (33kV) Where some is used in large factories
  • Some is stepped down further (11kV) for small factories
  • Rest is stepped down instead (230V) to be used in houses shops etc.
87
Q

SP13b - Why is electricity stepped up before transmission?

A
  • A higher voltage means a lower current.
  • A higher current would mean a higher power loss (P = I²xR).
  • So the lowest possible current is attained so that the least amount of energy is lost by heating.
  • Low resistance wires are also used (thicker).
88
Q

SP13b - What is the structure of a transformer?

A

A primary coil (connected to an a.c supply) and a secondary coil with differing amounts of turns, wrapped around an iron core.

89
Q

SP13b - How do transformers work?

A
  • Changing a.c current supplied
  • This produces a changing magnetic field in primary coil
  • The iron core is induced and carries this changing magnetic field
  • This creates a changing magnetic field in the secondary coil
  • This induces a changing a.c voltage in the wires connected to the secondary coil.
90
Q

SP13c - What is the voltage current transformer equation and what does it assume?

A

V(p) x I(p) = V(s) x I(s)

[assuming that the transformer is 100% efficient]

91
Q

SP13b - Which equation links voltage and turns across coils?

A

V(p)/V(s) = T(p)/T(s)

V = Voltage across coil

T = Turns in coil

92
Q

SP13c - What are the equations for power and energy?

A
  • P = I x V
  • E = P x t , so
  • E = I x t x V
93
Q

SP14a - What does kinetic theory state?

A

Everything is made of tiny particles

94
Q

SP14a - Describe the properties of a solid

A
  • Rigid
  • Fixed shape
  • Fixed volume
  • Cannot be compressed
95
Q

SP14a - Describe the properties of a liquid

A
  • Not Rigid
  • No fixed shape
  • Fixed volume
  • Cannot be compressed(ish)
96
Q

SP14a - Describe the properties of a gas

A
  • Not Rigid
  • No fixed shape
  • No fixed volume
  • Can be compressed
97
Q

SP14a - What happens when a substance changes state? (In terms of particles)

A
  • The particles change their arrangement
  • This leads to a change in density
  • The mass is conserved as the amount of particles remains
  • This is a physical change as it can be reversed and no new substances are formed
98
Q

SP14a - How does the density of a substance change between states and what is the exception?

A
  • Generally, as substances go from solid → liquid → gas, they become less dense
  • This is because the particles become more spread out meaning there are less in a certain volume
  • Water is the exception to this as ice is less dense than liquid water
99
Q

SP14a - What is density inc. formula?

A

Density is a measure of how many particles are packed in a space

Density(g/cm³) = mass(g) ÷ volume(cm³)

(ρ = m x V)

100
Q

SP14a CP - How do you find the density of an irregularly shaped object?

A
  • Set an electronic balance to 0 then place the object on it and record the mass
  • Set up a displacement can leading into an empty measuring cylinder and fill the can with water
  • Place the object in the can. If it floats, then push it down till it is just under the surface of the water
  • Read the value for the volume of water in the measuring cylinder (from the bottom of the meniscus)
  • This is the volume of the object. Do mass/volume to find the density
101
Q

SP14b - What is thermal energy?

A

The energy stored in the movement of particles that has been transferred to the system by heating

102
Q

SP14b - What is temperature?

A

A measure of the average speed/movement of the particles in a substance

103
Q

SP14b - What is specific heat capacity?

A

The amount of energy required to increase the temperature of 1 kg of a substance by 1°C (The diagonal lines of a heating curve)

104
Q

SP14c - What is the formula for specific heat capacity?

A

ΔQ = m x c x Δø

Change in energy(J) =

mass(kg) x specific heat capacity(J/kg°C) x change in temperature(°C)

105
Q

SP14b - What is specific latent heat?

A
  • The amount of energy required to change the state of 1kg of a substance (The horizontal parts of a heating curve)
  • This energy is given out when the doing the opposite state changes are equal to how much it takes
  • (energy needed for evaporating = energy released form condensing)
106
Q

SP14c - What is the formula for specific latent heat?

A

Q = m x L

Energy = mass x Specific latent heat

107
Q

SP14b - Describe the appearance of a heating curve describing what is happening

A
  • Time on x-axis temperature on y-axis
  • There will be a diagonal line going up steadily upwards
  • Eventually it will plateau and be a horizontal line for a bit
  • It will then continue to rise diagonally then plateau and then rise once more
  • The diagonal lines are where energy is transferred and stored as thermal energy and increasing the temperature
  • During the plateaus, the energy is being used to overcome the forces that hold the molecules together resulting in changes of state
108
Q

SP14d - What is the temperature of a gas and how can it increase?

A
  • A measure of the average kinetic enegry of the particles in the gas
  • By heating it up (providing thermal energy) the particles will start to move faster meaning a higher temperature
109
Q

SP14d - Why does an increase in temperature lead to an increase in gass pressure (for a fixed mass of gas)?

A
  • A higher temperatures means that the particles in the gas are moving fatser.
  • This means that they will have more frequent collisions with the walls of their container.
  • This means that the force exerted on the container is higher leading to a higher temperature.
110
Q

SP14d - What is the unit for pressure?

A

pascals (Pa)

[where 1 Pa = 1 N/m²]

111
Q

SP14d - What is absolute zero?

A
  • Once the temperature of a gas has reduced to -273°C (or 0K) then the particles in the gas have a pressure of 0 meaning they aren’t moving.
  • This is only theoretical as gases would normally condense to a liquid once reaching this low a temperture
112
Q

SP14d - What is the kelvin scale and how do you convert between celcius to kelvin v.v?

A
  • The kelvin scale has the same intervals as celcius but 0 K is equal to absolute zero (-273°C)
  • To convert K - °C - 273 and °C - K + 273
113
Q

SP14d - Describe the relationship between kelvin and the avergae kinetic energy of gas

A

Directly proportional

114
Q

SP14e - What is gas pressure?

A

When gas particles hit a surface, they produce a net force acting at right angles to the surface. We detect this as gas pressure

115
Q

SP14e - Why does decreasing the volume of gas (at a fixed mass and temperature) increase the pressure?

A
  • Inside a container, the pressure acts at right angles to the walls
  • If the same number of particles are in a smaller space, they will hit the walls of the container more often
  • This means the force on the walls increases. We detect this as a higher pressure
116
Q

SP14e - What equation links pressure and volume for a fixed mass and temperature?

A
  • P1 x V1 = P2 x V2
  • This means that an increase in pressure or volume will cause a decrease of the other by the same proportion
  • They are inversely proportionate
117
Q

SP14e - Why does pumping a bike tyre up increase the pressure of the pump?

A
  • More air is forced into the typre when you pump it
  • This increases the number of gas particles in a fixed volume
  • As a result, there is an increase in the frequency of collisions between gas particles and the (inner) surface of the tyre
  • This leads to more force exerted on and thus an increased pressure in the tyre
118
Q

SP14e - Why does the temperature of a tyre increase as you pump it?

A
  • Each time you push the pump handle, the force is transferring energy to the gas inside the pump (This is work done)
  • As the piston of the bike pump moves, the speed (KE) of any particles inside the particles increases as they bounce off it
  • This means that the average speed of the particles has increased and we detect this as an increase in temperature
119
Q

SP15a - What are the three things a force can do to an object?

A
  • Change shape(/size)
  • Change direction
  • Accelerate (Decelerate)
120
Q

SP15a - What is the name for a force changing the shape of an object and what is required for it to occur?

A

It is called deformation and requires two forces rather than just one.

121
Q

SP15a - What does it mean if an object elastically deforms?

A

The forces change the object’s shape but it returns back to its original shape when forces are removed. (e.g spring, diving board, and archer’s bow.)

122
Q

SP15a - What does it mean if an object inelastically deforms?

A

The forces change the object’s shape and it doesn’t return back to its original shape when forces are removed. (e.g Clay, Blu-tac, and spoons.)

123
Q

SP15a - How may some objects behave elastically and inelastically?

A

Some objects (like springs for example) will behave elastically. However, when the forces exceed a certain amount, they will become permanently deformed, behaving inelastically and keeping its new shape.

[Life Lesson #44: Don’t overextend yourself]

124
Q

SP15a - What is the extension of a spring?

A

The change in length of a spring when a force is applied

New length - old length = extension

125
Q

SP15a - How would you describe the relationship between force and length of a spring

A
  • It is a linear relationship (straight line) as long as the spring behaves elastically.
  • Once it is permanently deformed, the relationship is non-linear (curved).
126
Q

SP15a - What is the relationship between extension and force of a spring and rubber band?

A
  • Spring: They are directly proportional as it would be a straight line through the origin.
  • Elastic band: It behaves completely inelastically with a non-linear relationship
127
Q

SP15b - What is a spring constant?

A

The force (N) required to produce and extension of 1 metre

128
Q

SP15b - What is the equation linking force and spring constant?

A

F = k × x

Force (N) = Spring constant (N/m) × Extension (m)

129
Q

SP15b - What is the relationship between force and extension?

A

F ∝ x(Directly proportional)

130
Q

SP15b - What does the gradient of a Force/extension graph show you?

A

Sign gradient is Δy÷Δx it would be force/extension which will give you the spring constant of a spring

131
Q

SP15b - How may you be able to tell that a spring has a higher spring constant by holding it?

A

Stiffer springs have a higher spring constant (As they require more force to extend)

132
Q

SP15b - How do you calculate the work done when stretching a spring?

A

E = 1/2 × k × x²

Energy transferred by stretching (J) = 1/2 × Spring constant × Extension²

133
Q

SP15b CP - Describe how to find the spring constants of different springs.

A
  • Set up your equipment as shown
  • Measure the length of the spring without any weights at eye-level
  • Add 1 newton (100g) weights one at a time, measuring the new length at eye level each time
  • Take away the original length from all your values to get the extension
  • Repeat a few times and take the average of your results for reliability
  • Plot a graph of force/extension and calculate the gradient of the line. This will be the spring constant
  • If you want to find the work done for a particular extension, square that extension, divide by 2 and then multiply by the spring constant
134
Q

SP15c - What is the formula for pressure?

A

P = F ÷ A

Pressure (Pa) =

Force [normal to surface] (N) ÷ Area of that surface (m²)

135
Q

SP15c - What are the units for pressure?

A

Pa - Pascals, which is equivalent to N/m²

(however the m in N/m² can be changed to any other metric length value but won’t be equal to 1 Pa)

136
Q

SP15c - What are fluids?

A

Liquids or gases

(Because they f̶l̶o̶o̶o̶d̶ flow)

137
Q

SP15c - What is atmospheric pressure?

A

The pressure exerted perpendicular to any surface by the air at all times. It is highest at sea level around 100,000 Pa (1 atm)

138
Q

SP15c - What two things affect the pressure exerted by a fluid?

A
  • Depth of the fluid: The more particles above you, the higher pressure you will experience as more particles can produce a higher force. This is why pressure is highest at sea level and reduces as you increase altitude
  • Density of fluid: The denser the fluid you are in, the more particles there are in a fixed volume, the more particles can produce a force. This is why water pressure is higher than air pressure
139
Q

SP15c - When calculating total pressure when underwater, what must you do?

A

Find the pressure exerted by the water and add 100,000 Pa of air pressure

140
Q

SP15c - Why does a bag of crisps sealed at sea level expand when at higher altitudes?

A
  • When sealed at sea level, the air inside the bag will around 100,000 Pa
  • When taken to a higher altitude, the pressure outside the bag decreases
  • As the pressure inside the bag (acting outwards) is greater than outside the bag (acting inwards), the bag expands
141
Q

SP15d - What formula calculates the pressure due to a column of liquid?

A

P = h × ρ × g

Pressure [due to column] (Pa) =

height of column (m) × density of fluid (kg/m) × gravitational field strength (N/kg)

142
Q

SP15d - What is upthrust?

A

The upward force exerted on the bottom of an object in a liquid.

143
Q

SP15d - How do you calculate upthrust?

A

Difference in pressure between top and bottom of the object multiplied by the surface area of the bottom of the object

[Upthrust = Δh × ρ × g × surface area (m²)]

OR

Upthrust is the weight (in Newtons) of the liquid displaced when an object is placed in the liquid

144
Q

SP15d - If an object is floating what does this mean?

A

The density of the object is less than the liquid it is in. The lower the density, the better it floats (more will be above the liquid surface)

145
Q

SP12a - What is a permanent magnet?

A

A magnet that always has a magnetic field

146
Q

SP12a - What is a temporary magnet?

A

A magnet material that only has a magnetic field when in the field of another magnet.

147
Q

SP12a -When a temporary magnet enter a magnetic field and becomes magnetised, what can you say it is?

A

It is now an induced magnet

148
Q

SP12a - What are the four magnetic materials?

A
  • Iron
  • Steel
  • Nickel
  • Cobalt
149
Q

SP12a - What piece of equipment can be used to find the magnetic field of a bar magnet?

A

A plotting compass

150
Q

SP12a - What do two opposite parallel magnetic plates create?

A

A uniform parallel magntic field

151
Q

SP12a - What do the field lines aorund a bar magnet look?

A
  • They are going form north to south, increasingly spaced out the further away from the magnet.
  • They go in curves around the outside
152
Q

SP12a - How do we know that the earth has a magnetic core?

A
  • It has field lines similar to that of a bar magnet around it.
  • We can see this through compasses.
  • It is a core made of nickel and iron.
153
Q

SP12a - What is the key thing to remember about the earth’s poles?

A

Its geographic north pole is its magnetic south pole and vice versa

154
Q

SP12b - What does the direction of the magnetic field around a wire depend on?

A

The direction of the current

155
Q

SP12b - What can we use to figure out the direction of the current and how can this be done?

A
  • Curl your right hand into a fist and stick out your thumb.
  • Point your thumb in the direction of the current and the direction your finger curl aorund is the direction of the magnetic field?
156
Q

SP12b - When a magnetic field is shown what does a cross or a dot represent?

A
  • Cross means that the current is haeding away from you
  • Dot means the current is going towards you
157
Q

SP12b - What is he shape of a magnetic field around a wire?

A

Circular

158
Q

SP12b - When you coil a wire, what is it called?

A

A solenoid

159
Q

SP12b - The magnetic field of a solenoid is similar to that of _______

A

A bar magnet

160
Q

SP12b - What is the magnetic fieldat the centre of the solenoid similar to?

A

A uniform parallel field

161
Q

SP12b - What do you call a solenoid with a current flowing thorugh it?

A

An electromagnet

162
Q

SP12b - What are the ways you can make an electromagnet stronger?

A
  • Adding an iron core (a temporary magnet)
  • Increasing the current
163
Q

SP12b - What is the strength of the magnetic field around a wire dependant on?

A
  • The strength of the current (Stronger when higher)
  • The distance from the wire (stronger when closer)
164
Q

SP12c - When does the motor effect occur?

A

When a wire carrying a current enters a uniform parallel magnetic field

165
Q

SP12c - Why does the motor effect occur and what does it produce?

A

The magnetic field from the wire acting against the magnetic field from the uniform parallel field produces a force that acts on the wire.

166
Q

SP12c - What can be used to work out the direction of the force in the motor effect?

A

The left hand rule:

  • Set your hand so your thumb is up and your first and second fingers are at right angles.
  • Your first finger represents the direction of the field.
  • Your second finger represents the direction of the current.
  • Once these are lined up, the way your thumb is pointing will be direction of the force
167
Q

SP12c - How do you calculate the force exerted on a wire in the motor effect.

A

F = B I L

Force (N) =

Magnetic field strength (T) x Current (A) x Length of wire inside the UP field (m)

168
Q

SP12c - What are the two units and the alternate name for magnetic field strength?

A

Magnetic flux density:

  • T - Telsa
  • N/Am - Newton per amp metre
169
Q

SP12c - How do motors spin?

A
  • The motor effect is set up so that the wire returns back to where is started.
  • This means there are two sections of the wire inside the UP field with current travelling in different directions in each.
  • This means that the direction of force on one will be up and down on the other.
  • The wires are centered around a pivot which allows these forces to cause a turning motion.
  • This is the motor effect.
170
Q

SP12c - What is a split - ring commutator used for?

A
  • Once the side of the motor’s wire that is moving upwards has made a half turn it will be on the other side but still experiencing an upward force.
  • This would mean that the motor keeps spinning back and forth around that point without ever making a full turn.
  • The SR commutator means that once it has made a half turn the current will be ‘reset’ and change direction so the wire that was previously having a current going forward will now have it going back.
  • So the wire experiencing an upward force will now experience a downward force and vice versa.

GCSE Physics (17 decks)

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