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physics > Things You Got Arong Gcse Revision > Flashcards

Things You Got Arong Gcse Revision Flashcards

1
Q

What does flat line represent on velocity time graph. State two meanings

A

Constant velocity.
No acceleration

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2
Q

What does a curved line represent on distance time graph

A

Acceleration (speed is changing)

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3
Q

Give examples of 8 types of forces

A

-air resistance
-friction
-upthrust
-gravitional
-electrostatic
-compression (squeezing together)
-tension(stretching)
-reaction force

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4
Q

What three effects do forces have

A

Change speed
Change direction
Change shape

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5
Q

Icy rod conditions,travelling fast, worn out tyres all affect stopping distance.
Name one more feature that can affect stopping distance

A

Vehicle mass

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6
Q

What does a negative resultant force mean

A

Acts in opppostion to objects motion and so therefore slows them down

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7
Q

Small mass means….. acceleration because ….

A

More
Because mass is inversely promotional to acceleration

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8
Q

What three things can an unbalanced force do to an object

A

Causes it to accelerate so can,
-slow down
-speed up
-change direction

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9
Q

As speed of an object increase increases why does its air resistance increase

A

Because there is friction between the objects motion, and collisions with the air particles
So the air particles try to slow it down, called air resistance

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10
Q

Explain why when opening a parachute, velocity begins to decrease until a terminal velocity is reached

A

-air resistance is greater than weight
-this causes an upwards resultant force
-this causes deceleration, so the velocity begins to decrease (slows down)
-when velocity decreases, air resistance also decreases
-therefore air resistance and weight are now equal
-and object has reached terminal velocity

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11
Q

State the equation for hooks law, and state what hooks law is

A

F=Kx
That the force applied to an object is directly proportional to its extension, UP UNTIL THE LIMIT OF PROPORTIONALITY

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12
Q

How do you calculate the extension of a spring

A

New reading on ruler- reference point(intitial reading)

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13
Q

Describe the experiment for hooks law

A

1) set up a clamp and stand, and attach a spring without any masses to it
2)place a ruler next to it, MAKE SURE TO MEASURE AT EYE LEVEL TO AVOID PARRALEX ERROR, and measure intitial length of spring
CAN IMPROVE ACCURACY USES A FIDUCIAL MARKER
3)Add one mass at a time, and measure the new length of spring
4)calculate extension by doing new length- original length
5)repeat for increasing masses
6)then repeat whole experiment again three times and take an average
7)plot a graph to show with force on y axis and extension on x axis

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14
Q

Give a statement sthat links momentum and force

A

Force is the rate of change of momentum

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15
Q

What is a moment

A

The turning effect of a force, about a pivot

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16
Q

Principle of moments

A

If an object is balanced, the total clockwise moments equals the total anti clockwise moments about a pivot

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17
Q

Explain how a freely suspended object swings, in terms of moments and centre of gravity

A

-the objects weight acts at a distance from the pivot, which is the suspension point
-this creates a moment
-which causes it to swing
-and so the centre of gravity will now be directly vertically below the suspension point

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18
Q

Explain how to find the centre of gravity for an irregular shaped object

A

1)draw the point of suspension and suspend from that point, and suspend a plumb line for the same point, and wait until it stops moving
2)draw a line down the plumb line
3)suspend from another point with a plumb line and draw another line
4)the centre of gravity will be where the both lines intersect

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19
Q

What is the centre of gravity

A

The point through which the weight of the object acts

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20
Q

On a distance time graph, if a gradient becomes steeper this means,…
And if a gradient becomes less steep this means,…

A

Speed increases
Speed decreases

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21
Q

What does constant acceleration mean

A

That the velocity increases at a constant rate

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22
Q

If the driving force is the same of a car, state two reasons why the car could still experience a change in acceleration

A

Air resistance increases
Friction increases

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23
Q

Describe the difference between average speed and instantaneous speed

A

Average speed= total distance/total time, assumes that speed is constant and no acceleration

Instantaneous speed= speed at a particular moment. Can vary between two different parts of a ramp bc may have accelerated

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24
Q

Explain the difference in method between calculating the average speed of a car on a ramp
And calculating the speed at the bottom of the ramp

A

Average speed= measure time it leaves the top and the time it reaches the bottom
Then do distance divided by time

Speed at the bottom of the ramp is done using light gates, with a card on the car to detect it, connected to a computer. So light gates measure the time at the particular moment that it reaches the bottom
Then speed equals total distance divided by that time

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25
Q

What does a low terminal velocity suggest about the rate that an object falls at

A

It means that it falls at a much slower rate than an object that has a high terminal velocity
Because this means that it reaches constant speed much quicker than the one with high terminal velocity
So spends less time accelerating downwards

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26
Q

give the colours in a ring main circuit and what each one represents

A

blue, neutral wire
green yellow, earth wire
brown, live wire

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27
Q

if double insulation is present, is earthing required or not and explain why

A

double insulation means all parts of the wire are insulated,
therefore the earth wire would not be able to conduct a current, and so would not be needed.

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28
Q

explain how a fuse works, and give advantages and disadvantages of circuit breakers.

A

fuse contains a thin metal wire which melts when current is too high due to its low boiling point. this stops the current and so user can’t conduct an electric shock.

circuit breakers, doesn’t have to be replaced, more sensitive to changes

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29
Q

Explain how fueling aircraft can be dangerous and how this can be tackled

A

When aircraft is flying, friction with the air causes a charge to build up
So if a lot of charge has build up, it can escape to the earth and cause a spark to built up
And when refueling this spark can cause an explosion
Therefore earthing can be done which provides an alternative pathway the ground, and so removes the excess charge from the aircraft

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30
Q

Explain how a photocopier works

A

An image of the document is reflected onto the turning drum
The turning drum is positively charged, and is an insulator in dark area, and a conductor in light areas
So the area that is light gets discharged, and the dark area on the paper remain negatively charged
This then passes through to a toner which is positively charged, and so black powder sticks to this area
The image is then transferred to white paper
And is heated so that the toner sticks to the paper

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31
Q

Explain how to use an oscilloscope to measure the speed of sound in air

A

1) set a set frequency on a signal generator
2)attach two microphones to an oscilloscope which are equal distance away from each other
3)keep moving one microphone back until the waves for each microphone on the oscilloscope are synchronized, (because this is one wave length)
4)measure the distance between the two microphones
5) use equation V=FH

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32
Q

Explain how optical fibres work in endoscopes

A

Endoscopes contains a bundle of fibres
Light enters from an angle of incidence that is greater than the critical angle,
So it is totally internally reflected throughout the tube each time it hits the edge

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33
Q

Give two reasons why optical fibres are more useful in telecommunication rather than copper wires

A

Because they are thin so can transfer more information
They use less energy than copper

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34
Q

Give four ways to improve accuracy when doung the glass block experiment for refraction

A

-use a set square to ensure that the normal is completely perpendicular
-when drawing angles use a protractor with a higher resolution
-to ensure accurate values plot a graph for sin i against sin r
-take a mean value

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35
Q

What is the range of human hearing

A

20-20000HZ

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36
Q

Why can light waves not travel through a vaccum but sound waves can

A

Light waves need a medium to propagate through but sound waves do not

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37
Q

Give 4 properties of em waves

A

All transverse waves
All can be refracted and reflected
Can travel at speed of light in a vacuum
All transfer energy

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38
Q

Explain in terms of the Doppler effect what happens when a sound is heard from near by

A

The wavefronts are more squashed together
Therefore the wave length decreases
And so the frequency also decreases

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39
Q

Give some uses of radio waves and why
Give some uses of microwaves and why

A

Radio; radio and broadcasting communication. Bc can be reflected from earths atmosphere
Microwaves; cooking and satellite communication; bc can penetrate earths atmopshere

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40
Q

Give a hazard of microwaves
Give a hazard of visible light

A

Microwaves can penetrate human body tissue
Visible light can cause blindness if too bright

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41
Q

What is magnetic induction

A

When a magnetic material is placed in a magnetic field it will induce magnetism

42
Q

What is a permanent magnet, and what is a magnetically hard material

A

Permanent magnet produces its own magnetic field, and will not lose its magnetism
A magnetically hard material retain its INDUCED magnetism even after the magnetic field is removed from it
(So rmeber that a magnetic hard material only becomes a magnet after magnetism is induced in it, but permanent magnets are always magnets anyway)

43
Q

What three things do magnetic field lines show

A

-the shape of a magnetic field
-the size of magnetic field
-the direction of the magnetic field

44
Q

What is electromagnetism

A

When a current carrying wire produces a magnetic field around it

45
Q

Explain the magnetic field of a
1)circular current carrying wire
2)And of a solenoid

A

1)centre is that of a bar magnet, so goes from north to south, but around it there are concentric circles. You can use Fleming right hand rule to figure it out
2)centre is strong and uniform. The rest is like that of a bar magnet

46
Q

What is the motor effect

A

When a current carrying wire is placed into a magnetic field it experiences a force, due to the interaction between its own magnetic field and the other magnetic field

47
Q

Explain how a motor works;

A

1)the current carrying wire is perpendicular to the magnetic field and so each side of the wire experiences forces in opposite directions
2)this causes the wire to rotate
3)when the wire is in a vertical position, the split ring commutator reverses the direction of the current, and so the direction of the forces also change and the loop spins in oppsite direction
3)the split ring will be reverse direction of the current after every half turn to ensure that it continues to spin in one continuous direction

48
Q

Explain how a loud speaker works

A

-a coil of wire is wrapped around a circular permanent magnet, and an alternating current is passed through this coil which creates a changing magnetic field
-the permanent magent also exerts a magnetic field, so there is thus an interaction between the two fields
-this creates a force which causes the cone to move direction
-and because there is an alternating current supplied, the direction of the force will keep changing and so the cone will move backwards and forwards
-this movement causes the cone to oscillate, creating compressions and rare fractions and so producing sound

49
Q

What is electromagnetic induction

A

The creation of a voltage or current in a wire when it experiences a change in magnetic field (due to the cutting of field lines)

50
Q

Give four ways to increase the potential difference in terms of electromagnetic induction and explain how this happens

A

-increase the number of coils, because each filed line will be cut to produce pd and so more field lines cut, more pd produced
-increase the size of the cois, bc this means a larger surface area, which means more area of the coil will be cut so more pd
-increase the strength of magnetic field
-increase the speed, because field lines will be cut at a faster rate so more pd

51
Q

What does a step up transformer do and why
What does a step down transformer do and why

A

Step up transformer increases the voltage, does this bc electricity released from power stations can be released more efficiently, bc higher voltage means less current, and so less heat will be lost form the wires.

Step down transformer decreases voltage, does this because electricity released to homes needs to be transmitted safely, so lower voltage is more safe

52
Q

What keeps planets in orbit

A

Gravitational force
(Diff to gravitioanl field strength)

53
Q

What two factors affect gravitational field strength of a planet

A

Mass
Radius

54
Q

What is a galaxy
A universe
A solar system

A

Galaxy, collection of billions of stars
Universe, collection of billions of galaxies
Solar system, collection of planets that orbit a sun

55
Q

What is the orbit of a
Comet
Planet
Moon

A

Very elliptical
Slightly elipictal, mostly circular
Slightly elipctal, mostly circular

56
Q

A stars colour is dépendant upon…

A

Their surface temperature

57
Q

What are three ways that you can measure star brightness, and explain what they are

A

Absolute- brightness of a star from a fixed distance away
Apparent
Lumonsoty

58
Q

Explain life cycle of a star same size as sun

A

Nebula- clouds of hydrogen and dust are pulled together by gravitiaonl forces to form a nebula
Proton star- as more material is gathered, Grav forces increase, temp and pressure increases
Main sequence- these temps cause hydrogen fusion reactions to begin, this causes star to expand, so eventually out wards and inwards balance each other
Red giant- hydrogen nuclei run out so fusion stops, grav forces are largest and cause star to compress, temp increases. Now helium fusion begins, and star begins to expand and cool
White dwarf- outer layer is cast off, grav forces are largest, star compresses and temp increases.

59
Q

Explain life cycle of a star larger than the sun

A

Nebula- clouds of hydrogen and dust are pulled together by gravitiaonl forces to form a nebula
Proton star- as more material is gathered, Grav forces increase, temp and pressure increases
Main sequence- these temps cause hydrogen fusion reactions to begin, this causes star to expand, so eventually out wards and inwards balance each other
Large red super giant- fusion rections stop, grav forces are largest, compress the star. Temp increases, now helium fusion begins and causes the star to expand
Supernovae;fusion reactions stop, grav forces strongest, cause star to compress and it explodes
Neutron star; remaining matter forms a dense neutron star
Or black hole; if stars mass is massive enough, then it collapses into a black hole

60
Q

Label hertsprung russel diagram

A

Students answers

61
Q

Give 8 energy stores

A

-electriC
-kinetic
-geothermal
-magnetic
-elastic
-nuclear
-thermal
-electrostatic

62
Q

Give four ways of transferring energy

A

Through heating
Through radiation
Electrically
Mechanically

63
Q

Explain how convection currents form

A

Fluid is heated, so particles push apart, and expand
SoHot fluid becomes less dense than surroundings and rises
Cool fluid takes it’s place
Hot fluid eventually cools and contracts and sinks
This is called convection current

64
Q

What is the principle of conservation of energy

A

That energy is neither created or destroyed. And that the amount of energy in a closed system remains constant

65
Q

All objects emit thermal radiation, but the intensity of it depends upon;

A

Colour
Surface area
Temperature

66
Q

When heating different colourless beakers, which way is heat lost

A

Lost through all of them through convection and conduction,
However differences are due to thermal radiation, because there have different colours

67
Q

State four methods of reducing heat loss in home

A

Cavity wall insulation
Loft insulation
Reflective foil
Double glazing

68
Q

What are two definitions for power

A

The rate at which energy is transferred
The rate at which work is done

69
Q

Out of all the resources of energy, which two do not utilize a turbine to turn a generator

A

Wind energy
Solar energy

70
Q

State the energy transfers of all the 9 energy resources

A

Fossil— chemical, thermal, kinetic, electric
Nuclear—nuclear, thermal, kinetic,electric
Biofuel—chemical,thermal, electric
Wind—kinetic, electric
Water waves—kinetic,kinetic,electric
Tidal—kinetic,kinetic,electric
Hydroelectric—GPE,kinetic,electric
Geothermal—thermal,kineic,electric
Solar—-nuclear,thermal,electric

71
Q

Give some disadvantages of;
Tidal energy
Water waves energy
Hydroelectric energy;

A

Tidal—can disrupt shipping, few suitable locations
Water waves-unreliable bc relies upon wind, hazard tp boats
Hydroelectric-can increase flooding, harmful for wildlife

72
Q

Give disadvantages of
Wind
Solar
Geothermal
Biofuel

A

Wind- unattractive, unreliable
Solar-expensive, not reliable
Geothermal-can produce toxic gases from earth, few places are suitable
Biofuel- can use land that would be needed for other purposes eg food production

73
Q

Explain the pressure in a fluid

A

In a liquid or gas, the particles exert a force which is equal in all directions, and perpendicular to the surface

74
Q

Explain the relationship between temperture and pressure

A

Directly proportional relationship, assuming that volume is constant.
So when temperture increases,
The average kinetic energy store of the particles increases,
Therefore there are more frequent collision against the wall per second
So a larger force exerted per unit area
So pressure increases

75
Q

Explain relationship between volume and pressure

A

Assuming temp is constant, they are inversely proportional.
Bc when volume increases, the partciles are more spread out
Therefore there are fewer collision per second against the walls
Therefore a smaller force exerted per unit of area
So pressure decreases

76
Q

Explain how to investigate the specific heat capacity of a solid

A

1)Place two holes inside it and measure its mass
2)place a thermometer through it and measure the initial temperature
3)place an immersion heater though it and connect it to a joulmeter and power supply
4)wrap in insulating foam to reduce hea loss
5)once the temperture has reached its highest, record this and then record the energy shown on the joule meter.
6)use the equation e=mct

77
Q

What is absolute zero.
And describe how many degrees this is equal to

A

The temperature at which particles have 0 kinetic energy
Therefore do not exert any force per unit of area
So do not exert a pressure

0k= -273 degrees

78
Q

What is alternating current.

A

Current that continuously
changes direction
from positive to negative

79
Q

Which direction does current flow in?
Draw the circuit symbol for alternating current

A

Positive to negative
Look online

80
Q

Three advantges and two disadvantages of hydroelectric energy

A

Can respond to increased changes demand
Not weather dépendant
Large energy output for installation

May require a mountainous region
Flooding

81
Q

Which types of energy resources involve transfer of thermal energy

A

Bio fuels
Fossil fuels
Geothermal
Nuclear
Solar

82
Q

Explain how redshift gives evidence for the Big Bang

A

Distant galaxies have a larger red shift, which means that their observed wave length increases
This means that more distant galaxies are moving away faster than closer ones
The speed and distance are directly proportional, which supports the idea that the universe is expanding.
Supports ides of big band, where the universe began from a small hot and dense region and expanded into the universe

83
Q

What is the big band theory

A

That the universe began from a small hot dense region which began to expand into the universe

84
Q

What is cosmic background wave radiation and how does it give evidence for the Big Bang

A

It is the remains of thermal energy found in all directions as a result of the Big Bang,
Which Italy began as short wave gamma radiation, but has stretched out over time to become microwave radiation.
So this supports the idea of the big bang as it is suggested that it began form a small hot and dense region that expanded

85
Q

in speed of sound in air experiment, how much distance should u stand apart minimum

A

100m

86
Q

Purpose of a commutator in a dc motor

A

1)switches the contacts with the coil by swapping the negative and positive connections every half turn
2)this reverse the direction of the current
3) so the forces continue to act in the same direction
4)and so the coil continues to rotate in the same direction aswell

87
Q

Relative masses,
And relative charge of three main types of radiation

A

Alpha mass-4
Beta mass- 1/1800, virtually none
Gamma mass-0
Alpha charge-2+
Beta charge-1_
Gamma charge-0

88
Q

How is beta formed

A

Produced in the nuclei when tit splits into a proton and fast moving electron

89
Q

In the beta decay equation, what happens to the mass number and what happens to he atomic number and why

A

Atomic number increases because one proton is gained
Mass number stays the same because a neutron is also effectively lost so number balances out

90
Q

Apart from carbon-14, and food, give two other sources of naturally occurring radiation and explain how

A

Cosmic rays from space;
-sun emits protons which enter at high speeds into the atmosphere, these collide with molecules in the atmosphere and form gamma rays
Radon gas;
-uranium a radioactive material decays to produce radon gas which is an alpha emmiter

91
Q

Give three sources of man made radiation

A

-nuclear fallout(residue from nuclear explosion0
-nuclear accident
-medical equipment

92
Q

Defintion of contamination
Defintion of irradiation

A

Contamination-the unwanted presence of a radioactive material on another material, where the material itself becomes radioactive
Irradiation-when a source is exposed to radiation, but the source itself does not become radioactive

93
Q

Definition of activity

A

The number of decays per second in the unstable nuclei of a source

94
Q

Inside a thickness gauge, what happens when the paper is thick

A

More beta is absorbed, therefore less is penetrated through to be detected by the detector

95
Q

What type of radiation would a radioactive tracer use and why, and what would it not use

A

Would use gamma because it is hihgly penetrating so can penetrate through tissue.
Would not use alpha howver bc strongly ionizing could mutate cells.

96
Q

What type of radiation could u use for external radiotehrapy and why
What type could u use for internal radiotherapy and why

A

External, use gamma, bc highly penetrating
Internal use beta, less penetrating

97
Q

What is the first step of nuclear fission

A

A slow moving electron is fired and absorbed by an unstable nucleus causing it to become more unstable and thus splitting into two daughter nuclei.

98
Q

Three products released from nuclear fission

A

Energy
Two or three protons
Gamma rays

99
Q

Function of;
Moderator
Control rod
Fuel rod
Coolant

A

Moderator-slows done neutrons so that they can be better absorbed
Control rod-absorbs neutrons to limit the rate of fission
Fuel rod-made of uranium or plutonium and is where fission occurs
Coolant-absorbs excess heat energy which can then be used to convert e water to steam, turbine, generator

100
Q

Range of human hearing

A

20Hz to 20,000Hz (or 20Khz)

101
Q

How to measure specific heat capacity using a voltmeter and ammeter

A

Place the beaker on the digital balance and press ‘tare’
Add approximately 250 ml of water and record the mass of the water using the digital balance
Place the immersion heater and thermometer in the water
Connect up the circuit as shown in the diagram, with the ammeter in series with the power supply and immersion heater, and the voltmeter in parallel with the immersion heater
Record the initial temperature of the water at time 0 s
Turn on the power supply, set it at approximately 10 V, and start the stopwatch
Record the voltage from the voltmeter and the current from the ammeter
Continue to record the temperature, voltage and current every 60 seconds
Until final temperature reached
Use P=IV and E=PT
And then C= E/MQ

102
Q

Nuclear fusion dienfiton according to markscheme

A

The creation of a larger nucleus from smaller nuclei
Resulting in a loss of mass
And energy being released

physics (10 decks)

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