Paper 1 Hard Stuff Flashcards
(86 cards)
1
Q
Waves
A
transfer energy and information without transferring matter
2
Q
Longitudinal vs Transverse
A
Longitudinal: oscillates parallel to direction of energy travel
Transverse: oscillates perpendicular to direction of energy travel
3
Q
Frequency vs Time Period
A
Frequency: number of waves passing a particular point per second (Hz)
Time Period: time it takes for one complete wave to pass a particular point
4
Q
Current
A
rate of flow of charge
5
Q
Alternating Current vs Direct Current
A
Alternating: constantly changing direction
6
Q
What are the factors that affect gravitational field strength of an object?
A
- Mass
- Planet with larger radius has a weaker gravitational field strength at surface as it is further away from the centre
7
Q
Comet is made up of
A
balls of rock and ice
8
Q
Galaxy
A
A large collection of billions of stars
9
Q
Universe
A
A large collection of billions of galaxies
10
Q
Magnetically Hard vs Magnetically Soft
A
Magnetically Hard: permanently magnetised, e.g. steel, cobalt, nickel
Magnetically Soft: lose magnetism once no longer exposed to magnetic field, temporary
11
Q
Electric current in a conductor
A
Produces a circular magnetic field around it (right hand grip rule)
12
Q
Principle of Conservation of Energy
A
Energy is never created nor destroyed
13
Q
Conduction
A
- Transfer of thermal energy by the vibration of atoms within a substance
- Metals are good conductors (electrons that can move easily)
14
Q
Convection
A
- Liquid/gas expand when heated, particles take up more volume
- Particles remain the same size but are further apart
- Hot liquid/gas is less dense (rise)
- Cold liquid/gas is denser (falls)
- Convection current: transfers heat from place to place
15
Q
Radiation
A
- Transfer by infrared waves
- Quick travel in straight lines
16
Q
Light and Shiny
A
- Good reflector
- Poor absorption
- Emits less infrared radiation than dark at same temperature
17
Q
Dark and Matte
A
- Poor reflector
- Good absorption
- Better at emitting infrared radiation
18
Q
Next to a heat source…
A
dark object heats up faster
19
Q
What does hotter temperature mean for emission?
A
- Emits greater infrared radiation
- Frequency of EM radiation emitted increases
20
Q
How do you reduce unwanted energy transfer?
A
- Use an insulator (e.g. foam, feathers)
- Traps air, prevents heat transfer by conduction, prevents convection currents
21
Q
How do you investigate thermal conduction?
A
- Copper rod, steel rod
- Drawing pins stuck to metal rods with petroleum jelly
- Shows how heat is transferred along metal rods from middle to cool ends
- Drops off in sequence (copper better)
- Controls: rod same diameter, drawing pin same distance from store
22
Q
How to determine density of irregular object?
A
- Mass: a balance
- Irregular object: eureka can, measured displaced volume
23
Q
Similarities of waves in EM spectrum
A
- Transfer energy
- Travel at speed of light in a vacuum
- Transverse waves
- Can be reflected and refracted
24
Q
Red vs Blue (wavelength and frequency)
A
- Red: longer wavelength, lower frequency
- Blue: shorter wavelength, longer frequency
25
Law of Reflectioin
angle of incidence = angle of reflection
26
Angle to measure is
between ray and normal
27
Experiment to investigate the refraction of light
- Glass block, shine light through
- Use x to mark path
- Connect with ruler
- Draw normal where ray enters
- Measure angle i and angle r
- Repeat different angles and materials
28
Incident ray bending towards normal
- Denser material
- Slower
29
Incident ray bending away from normal
- Less dense material
- Faster
30
Doppler Effect
- Sound is constant when stationary
- As moving towards, wavefronts in front are compressed, wavelength smaller, higher frequency (higher in pitch)
- As moving away, wavefronts spread out behind, wavelength greater, lower frequency (lower in pitch)
31
Factors that affect thinking distance and braking distance
- Thinking Distance: tiredness, speed of car, drugs, alcohol
- Braking distance: car mass, car speed, brake conditions, tyre conditions, road conditions
32
Hooke's Law
Extension is directly proportional to force applied
33
Terminal Velocity
- Weight is acting upon
- Decelerates less as drag increases as it hits more air particles
- Downwards force gets smaller
- Until drag = weight, no acceleration = no resultant force = terminal velocity
34
Advantages of Parallel and Series
Parallel: components switch off independently, if one component breaks, current can still flow, bulbs have similar brightness
- Series: cheaper, one switch turns all on, lower power consumption
35
Ohmic Resistor IV graph
Linear, directly proportional
36
Filament Lamp IV graph
S shape
37
Diode IV graph
Along x-axis and shoots up on positive side
38
Current is __ across components in series
same
39
Current is __ across components in parallel
shared
40
Voltage is __ across components in series
shared
41
Voltage is __ across components in parallel
same
42
Pressure at a point in gas or liquid which is at rest is...
equal in all directions
43
Gas Laws
- Rapid, random motion
- Hits the walls, exerts force
- pressure = force/area
44
Celsius convert to Kelvin
+ 273
45
Same no. of particles in a container in smaller volume...
hits walls more often, more collisions per second, larger force, increases total pressure
46
Temperature Law
Pressure directly proportional to temperature, linear (as long as fixed mass of gas at constant volume)
47
Boyle's Law
Pressure inversely proportional to volume, non-linear (as long as fixed mass at constant temperature)
48
How to increase force on a current-carrying conductor?
- Increase magnitude of current
- Increase magnet strength
49
Voltage
Energy transferred per unit charge
50
Motor Effect
- Current flows through wire
- Magnetic field created around
- Interaction between field induced and field from permanent magnet
- Produces force on wire
- Split ring commutator changes direction of current every half turn
51
Loudspeaker
- Alternating current from source passes through coils in speaker
- Current constantly changes direction
- Current creates magnetic field around coil
- Interaction between field induced and field from permanent magnet
- Produces constantly changing force on coil
- Coil vibrates in and out, moving the cone
- Cone causes vibrations we hear as sound waves
52
Sources of Background Radiation
- Cosmic rays
- Medical equipment
- Rock and soil
- Radon in air
- Food and drink
53
Half-Life
The time it takes for the remaining number of radioactive nuclei to halve
54
Contamination
Material containing radioactive atoms is deposited on materials, skin and clothing, making the object radioactive
55
Irradiation
Object exposed to radiation, but the object itself does not become radioactive
56
Uses of radioactivity
- Medical tracer
- Radiotherapy
- Pipe tracers
- Sterilisation
- Carbon dating
57
Ionisation
Losing/gaining electrons
58
Alpha
- Strong ionising power
- A few cm in air
- Stopped by paper
- From helium nucleus
59
Beta
- Moderate ionising power
- Around 1m in air
- Stopped by 5mm aluminium
- From fast moving electron
- Neutron converted to proton and electron (+1 atomic number)
60
Gamma
- Very weak ionising power
- At least 1km in air
- Stopped by 10cm lead
- From electromagnetic wave
61
Critical Angle
Produces of angle of refraction of 90 degrees, along the boundary of the surface, must be from denser to less dense medium
62
Incidence > Critical
total internal reflection
63
Where is total internal reflection used?
Transmitting signals along optical fibres in prisms
64
Fission
Heavy atoms split into smaller, lighter atoms, releases energy
65
Fusion
Lighter atoms are forced to join together to make heavier atoms, releases energy
66
Radioactive decay
Radioactive isotopes of elements provide large proportion of heat within the sun through radioactive decay
67
How can the nucleus of U-235 be split?
- Collision with neutron
- Releases two daughter nuclei, some neutrons, gamma radiaiton
68
How can a chain reaction be set up?
- Neutrons released may hit others
69
What are control rods?
- Boron/cadmium
- Absorb neutrons
- Adjust rate of fission
70
What is a moderator?
- Absorbs some KE of neutrons to slow it down
- More easily absorbed by 235 nuclei
71
What is shielding?
- Reactor vessel made of steel, surrounded by 5m thick, concrete later
- Prevents radiation/neutrons from escapting
72
Fusion in Sun
- Isotopes of hydrogen colliding at high speeds, creating large nuclei: helium
73
What are the conditions that fusion has to happen at?
- Very high temperature and very high pressure
- Overcome repulsive forces between positively charged nuclei, increase chance of fusion
74
How does generator work?
- Coil rotating within field
- Cuts magnetic field lines while turning
- Voltage induced
- Connects to existing circuit
- KE turns to electrical energy
75
Star Colours
(hottest, brightest blue) OBAFGKM (coldest, dimmer red)
76
Sequence of Star Evolution (similar mass to sun)
- Nebula
- Main Sequence
- Red Giant
- Planetary Nebula
- White Dwarf
77
Sequence of Star Evolution (larger mass than sun)
- Nebula
- Main Sequence
- Red Supergiant
- Supernova
- Neutron Star/Black Hole
78
Nebula
- Large clouds of dust and gas particles
- Drawn together by gravitational forces over millions of years
- Particles so close that temperature and pressure increases
- So large that nuclear fusion of hydrogen and helium nuclei occur
- Releases massive amounts of energy in the form of light and heat
79
Main Sequence
- Fusion produces forces that make the star expand outwards
- Gravitational force pulls particles within inwards
- Two opposing forces balanced = stable = constant size and temperature
80
Red Giant/Red Supergiant
- Hydrogen fusion stops as star runs out of fuel
- Gravitational force > fusion
- Collapses inwards and compresses
- Even higher temperature
- Fusion of Helium Nuclei
- Increased power output = expansion
- Larger = cooler surface = red
- RS: produces all elements up to iron
81
Planetary Nebula/Supernova
- Occurs when red giant unstable
- Expels outer layer of gas and dust into space
- SN: Exploding star, throws gas and dust into space so another nebula forms
82
White Dwarf
- Fusion stops as star runs out of helium
- Gravitational force collapses inwards and compresses again
- Heat increases, emits white light
- Squashed very small, very desne
- When cools down becomes black
83
Neutron Star
- Made entirely of neutrons
- Dense core remains
84
Black Hole
- Large enough to compress further
- Gravity so strong no light can escpae
85
Air is
a good insulator
86
What is a fuel rod?
Provides material for fusion
