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IB PHYSICS
Higher
273
Physics
Not Applicable
03/31/2012

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Term
Adiabatic
Definition
Delta Q = 0
Term
Isothermal in IDEAL GAS
Definition
T = constant
Delta U = 0
Term
State the law of conservation of charge
Definition
Charge is neither created not destroyed. Charge is always conserved
Term
Electrical property of insulator
Definition
Non metals TH electrons are tightly bound.
Term
Electrical conductivity of a conductor
Definition
Metals
Delocalised electrons
Term
State coulombs law
Definition
The force between two charges is directly proportional to the product of their charges and indirectly proportional to the square of the distance between them.
Term
Electrical field strength
Definition
Force per unit charge experienced by a small positive test charge in that electrical field
Term
Two assumptions for coulomb's law
Definition
1. Two point charges
2. Separation is large
Term
Newton's law of gravitation
Definition
Force between two point masses is directly proportional to the product of their masses and indirectly proportional to the square of the distance between them. Given the distance is large in comparison with their radii
Term
Gravitational field strength
Definition
Force per unit mass experienced by a small point mass in that field.
Term
Gravitational potential energy
Definition
Work done per unit mass in moving a point mass from infinity to point P in a gravitational field
Term
Electric potential
Definition
Work done in moving a small positive test charge
Term
Electrical potential energy
Definition
Work done in moving a small positive test charge from infinity to a point p in the electrical field
Term
Newton's First Law
Definition
In the absence of external forces a body at constant velocity or at rest will remain at constant velocity.
Term
Displacement
Definition
Distance moved in a particular direction
Term
Velocity
Definition
Rate of change of displacement
Term
Speed
Definition
Rate of change of distance
Term
Acceleration
Definition
Rate of change of velocity
Term
Instantaneous
Definition
At a given point in time
Term
Average
Definition
Total divided by total no
Term
Outline conditions under which uniformly accelerated motion may be applied.
Definition
Constant acceleration
Term
Air resistance on falling objects
Definition
Decreases velocity
Term
Terminal speed
Definition
Constant velocity when force of air resistance = force of gravity
Term
Newton's Second law of motion
Definition
Force is directly proportional to the product of the mass and the acceleration. Force is directly proportional to the rate of change of momentum
Term
Translational equilibrium
Definition
No net force
Term
Newtons Third law of motion
Definition
For every action there is an equal and opposite reaction.
Term
Momentum
Definition
Product of mass and velocity
Term
Impulse
Definition
Change in momentum
Term
Law of conservation of linear momentum
Definition
Total momentum is constant in the absence of external forces.
Term
Work
Definition
Directly proportional to the product of the force and displacement
Term
Kinetic energy
Definition
Directly proportional to the product of the mass and the square of the velocity
Term
Gravitational potential energy
Definition
Directly proportional to the product of the mass and change in height.
Term
Principle of conservation of energy
Definition
Energy cannot be created nor destroyed. Energy can only be transferred.
Term
Gravitational potential
Definition
Work per unit mass required to move a point mass from infinity to point P in the gravitational field
Term
Power
Definition
Rate of change of energy transferred
Term
Gravitational potential energy
Definition
Work done in moving a point mass from infinity to a point P in the gravitational field
Term
Relationship between equipotential surfaces and gravitational field lines
Definition
Perpendicular
Term
Internal energy
Definition
Total potential energy
Term
1 Celsius to kelvin =
Definition
Add 273 to Celsius therefore 274
Term
Specific latent heat
Definition
The specific latent heat of a substance is the energy required to change the phase of 1 kg of a substance
Term
Pressure
Definition
Force per-unit area
Term
State the assumptions of the kinetic model of an ideal gas (six)
Definition
1. Spherical
2. Elastic collisions
3. Volume of molecules are very small in comparison to the volume of the gasp
4. No forces of attraction between molecules/ atoms
5. Time of collision much less than time between collisions.
6. Newtons laws apply
7. No gravitational effect
8. Random motion
9.
Term
Temperature
Definition
Average random kinetic energy of the molecules of an ideal gas
Term
Ideal gas versus real gas
Definition
An ideal gas cannot be liquefied
Term
Absolute Zero - ke of particles and entropy =
Definition
Kinetic energy of molecules are zero and no entropy
Term
First law of thermodynamics
Definition
Energy is neither created nor destroyed it can only be transferred
Term
Isochoric
Definition
Change in volume = zero
Work done = 0
Change in internal energy = change in energy transfer
Term
Isobaric
Definition
Change in pressure = 0
change in internal energy = change in energy transfer change in the work done
Term
Isothermal
Definition
For an ideal gas isothermal = 0 change in internal energy
Change in energy transferred = – change in the work done
Term
Adiabatic
Definition
Change in energy transfer = 0
Change in internal energy = change in the work done
Term
Second law of thermodynamics
Definition
Entropy of the universe will always increase
Term
Entropy
Definition
Degree of disorder in the system
Term
Displacement (waves)
Definition
Distance of any point from equilibrium position
Term
Amplitude
Definition
Maximum displacement from equilibrium position
Term
Frequency
Definition
Number of cycles per second (hertz)
Term
Period
Definition
Time taken to complete one cycle
Term
Phase difference
Definition
Fraction of a cycle by which one source moves behind the other
Term
Simple harmonic motion
Definition
Motion where the acceleration is directly proportional to the displacement but in the opposite direction
Term
Damping
Definition
Force that is always in the opposite direction to the direction of the motion of the oscillating particle. The force is the dissipative force.
Term
Natural frequency of vibration
Definition
Frequency at which an object or particle will oscillate at in the absence of external forces
Term
Forced oscillations
Definition
forced to go at a frequency other than its natural frequency of vibration
Term
Resonance
Definition
Natural frequency of oscillation = driving frequency causing the maximum amplitude
Term
Degraded energy
Definition
THERMAL energy that is lost to the surroundings and is no longer available to perform useful work
Term
Energy density
Definition
Energy released per unit mass
Term
Four possible reasons (models) for global warming
Definition
Greenhouse gases
Solar activity
Volcanic activity
Earth orbit
Term
Evidence that links global warming and increased amount of greenhouse gases
Definition
International ice core research - notably ice cores drilled from
Vostok in 1998 relate temperature change to CO2
Term
Albedo
Definition
Ratio of the power of radiation reflected to the total power incident on the body.
Term
Factors that determine albedo 3
Definition
Time of year, latitude, environment: desert land, forests , water
Term
Greenhouse Effect
Definition
Warming of the earth caused by infrared radiation emitted by the earth surface, which is absorbed by various gases in the earth's atmosphere. Primary gases responsible are water vapour, carbon dioxide, methane and nitrous oxide
Term
Black body
Definition
A theoretical body that is a perfect emitter
Term
Increase the temperature of a blackbody will increase...
Definition
The emissivity
Term
Stefan – Boltzman Law
Definition
The power (energy per second) is directly proportional to the product of the surface area, absolute temperature tk the fourth power and the properties of the surface.
Term
Surface heat capacity
Definition
Energy required to raise the temperature of one unit area of the planets surface by 1°
Term
Convert 29 to binary
Definition
11101
Term
LSB
Definition
Right hand side
Term
MSB
Definition
Left hand side
Term
LP's (Long Playing Record)
Definition
Sound is a vibration of particles across a medium.
The vibration of sound vibrates the needle. The needle makes grooves in the record.
Upon playback the needle retraces the grooves.
Vibrations are amplified and then fed-into a reader.
Term
CD (5Points essential)
Definition
Sequence imprinted onto a CD. Covered in a continuous spiral of PITS and lands. LASER light is used - MONOCHROMATIC. Light hits a pit or land directly then all the light reflects back and there is no change. Where between the edge of the pit and land the light had to travel y/2 more as the depth of the pit is (Y/4)! Therefore out of phase and causes DESTRUCTIVE INTERFERENCE(1)
Term
Digital advantages
Definition
Retrieval speed, reproducibility, portability, manipulation of data
Term
Implications for society of increasing capability of data storage.
Definition
Data can be retrieved by criminals easily - data has the potential to harm in the wrong hands.
Term
Capacitance
Definition
The charge per-unit potential difference that can accumulate on a conductor.
Term
CCD.
Definition
Charged coupled devices. Stores and displays images. Silicon chip (semiconductor) divided into millions of small areas known as pixels. Each pixel behaves as a capacitor. When light is incident on a pixel an electron is released. The number of electrons released depends upon the intensity of light. More intense light releases more electrons and thus has a greater negative charge.
Each pixel has a coordinate which is read out and digitalised by discharging each pixel.
Term
Image retrieved on
CCD
Definition
The charge is transferred across the CCD a row at a time. Before the next row arrives, the charge is moved to the readout pixel one pixel at a time. The charge is converted to a potential difference which is then stored in binary form. A potential difference is applied to move the next row down.
Term
Quantum efficiency
Definition
Ratio of the number of photo electrons emitted to the number of photons incident on the pixel
Term
Magnification
Definition
The ratio of the length of the image on the CCD to the length of the object
Term
Just resolved on a CCD
Definition
Images of the points are at least two pixels apart
Term
CCD advantages
Definition
image capturing in a large range of the electromagnetic spectrum.
Also good in low intensity light
Term
CCD to image.
Definition
Electrodes measure the pd developed across each pixel. This is then converted into a digital signal. Pixel position is also stored
Term
Magnetic flux
Definition
Product of the normal component of the magnetic field strength and the area that it links.
=BAcos(•)
Term
Evidence for nuclear model of the atom
Definition
Geiger – Mardsen experiment
Term
Limitation of the simple model of the nuclear atom
Definition
Electrons travelling in orbits which are therefore accelerating should emit EM radiation as accelerating charges emit electromagnetic radiation. This would lead to a loss of energy, resulting in their electrons spiralling in words, towards the nucleus.
Term
Nuclide
Definition
Nuclei with differing number of protons
Term
Forces inside a nucleus
Definition
Positive protons repel (coulomb interaction).
Strong nuclear force is an attractive force between nucleons (short range nuclear interaction).
Term
BETA
Definition
Proton electron = neutron
BUT NO ELECTRON IN
NUCLEUS SO...
Proton = neutron (opposite electron)
Proton = neutron positron neutrino
Term
Beta-
Definition
Neutron = proton electron antineutrino
Term
Biological effects of ionising radiation
Definition
High dose: death, loss of coordination
Med: damages stomach
Term
Nucleus stability
Definition
Dependent on the ratio of neutrons to protons
Term
Radioactive decay
Definition
Random and spontaneous. Rate of decay decreases exponentially time
Term
Radioactive half life
Definition
Time taken for undecayed nuclei to halve
Term
Decay constant
Definition
Probability that the nucleus will decay at any second
Term
Explain what artificial (induced) transmutation is and give an example.
Definition
Atoms of one element are transferred into atoms of other elements by inducing nuclear reactions.
By Bombing target material with high-energy particles
Eg in a tokamak - hydrogen converted to plasma
Term
Unified atomic mass unit
Definition
Equal to 1/12 of the mass of an atom of carbon 12
Term
Mass defect
Definition
Difference between mass of nucleus and total mass of nucleons
Term
Binding energy
Definition
Energy required to separate nucleons in a nucleus or the energy released when nucleons come together to form the nucleus
Term
Nuclear fission
Definition
One large nuclei split into two smaller nuclei. Required high-temperature, high-pressure, control rods
Term
Nuclear fusion definition and conditions
Definition
Two small nuclei join to form one big nuclei. High-temperature, high-pressure and magnetic fields.
Term
Photoelectric effect
Definition
Electromagnetic radiation is incident on a metal surface. If the light is of a sufficient frequency, a photon is absorbed which in turn releases a valence electron. 1 absorbed photon = 1 electron. Showed light is particle like.
Term
Milikan's experiment
Definition
Piece of metal and collecting plate placed in a vacuum (atoms do not interfere with photon electron path) - with a gap between the two. Collecting plate is connected to the negative negative terminal of the battery. Light of a specific wavelength is shone onto metal. Only electrons with sufficient kinetic energy can collect on the plate. Apply a stopping potential on the negative terminal - high pd jar causes the current to fall as the electrons do not have sufficent energy to overcome the pd. the last electrons to leave have the max kinetic energy. Therefore the voltmeter reads the
Max ke of the electrons. Plot max ke against photon freq
Term
Photoelectric effect dispelled wave theory
Definition
1. No time delay
2. Increasing intensity does not have impact - only increasing frequency.
3.
Term
De Broglie hypothesis
Definition
All matter and radiation have a wave particle duality
Term
Davison – Germer experiment
Definition
Test the duality of matter.
To everyone electrons were always the fundamental particles.
Shooting electrons at crystal surface which resulted in diffraction patterns
Term
Outline laboratory procedure for producing and observing atomic spectra
Definition
Emission in a prism. Absorption in spectrometer.
Term
Electron in the box model
Definition
The model assumes that, if an electron confined to move in a one dimension by a box, the De Broglie waves associated with the electron will be standing waves. Wavelength = 2L/N
Term
Schrodinger model of hydrogen atom
Definition
Assumes electrons and atoms can be described by wave functions. Only certain wavelengths that lead to standing waves are allowed. Electrons = undefined position.
Amplitude of wave function SQUARED = probability of finding electron
Term
Heisenberg uncertainty principle
Definition
Cannot know the position and momentum
Or time and energy
Term
Estimating radii of nuclei
Definition
Time = 0
Term
Brain bridge mass spectrometer
Definition
Draw schematic diagram
Term
Evidence for existence of nuclear energy levels
Definition
Alpha particles have discrete energies as do gamma ray Spectra.
Term
Beta energy Spectra
Definition
Continuous therefore neutrinos were postulated to account for the spectra
Term
Measuring long half lives
Definition
Mass has to be determined at t=0. After some time t, the undecayed nuclei are separated and the mass determined. Using M=moe-yt. From this the half life is calculated.
Term
How to measure short-term half life?
Definition
Number of decays that occur in a specific time interval are unmeasured and graphed against time
Term
Smaller wavelength on CD = advantages (4)
Definition
More layers on Bly ray dial.
Wavelength smaller therefore higher resolution
Track separation can be smaller
Pit spacing can be smaller
More information stored
Term
Diagram of Geiger
Mardsen.
Definition
1. Radon lead box.
2. Thin gold foil
3. Vacuum
4. Detector
Term
Critical damping
Definition
Returns to equilibrium without performing oscillations
Term
Overdamping
Definition
Same as critical damping (ie no oscillation)
Takes much longer to stop
Term
Longitudinal
Definition
Disturbance that travels parallel the direction of energy transfer. Transfer of energy by means of vibrations.
Term
Transverse
Definition
Disturbance that moves perpendicular to the direction of energy transfer
Term
Crest
Definition
Point of maximum amplitude
Term
Trough
Definition
Point of the minimum amplitude
Term
Compression
Definition
Higher than normal density
Term
Rarefaction
Definition
Lower than normal density
Term
Intensity (wave)
Definition
Energy transferred by wave over the product of the area and time
Term
Intensity is proportional to…
Definition
Amplitude squared
Term
Where resonance is useful
Definition
Microwave generators, quartz oscillators
Term
Examples where resonance is dangerous
Definition
Bridges collapse
Term
Wave pulse
Definition
Disturbance
Wave profile
Term
Can transverse waves propagate through gases?
Definition
Not in the way gases do. It prefers a vacuum
Term
Ray wavefront
Definition
Rays are perpendicular to wavefronts
Term
Electromagnetic wave speed in free space and orders of mag of wavelengths.
Definition
Travel at same speed (3*10^8)
Look at pix
Term
Law of reflection
Definition
Angle of incidence = angle of reflection.
Term
Snell's law
Definition
Ratio of the sin(incidence angle) to the sin(refracted angle) equals the ratio of the velocity in medium 1 to the Velocity in the second medium.
Term
Refractive index
Definition
Speed of light in a vacuum (c=3*10...) / speed of light in that medium
Term
Principle of superposition
Definition
When two waves pass through the same region of space at the same time the resultant displacement is the sum of their separate displacements.
Term
Nature of standing waves (3things)
Definition
No net energy transfer
Every point on the wave has a different amplitude.
In phase between two nodes.
Term
How do you form a standing wave
Definition
Two waves of the same amplitude and frequency travelling in opposite direction must pass through each other.
Term
Modes of vibration (open)
Definition
First/ fundamental harmonic: 1 node
Term
Modes of vibration (closed)
Definition
1 antinode
Term
What is meant by the Doppler Effect
Definition
Apparent change in frequency when 1. A wave source is moving and there is an apparent change in wavelength of wave.
2. An observer is moving resulting in an apparent change in wave speed.
Term
Describe doppler effect for when source is moving
Definition
A source moving at constant speed towards an observer emits a constant frequency. As the source moves towards the observer there is an apparent change in wavelength according to the observer. Increasing the frequency. VISA VERSA FOT SOURCE MOVING AWAY FROM OBSERVER FREQUENCY DECREASES.
Term
Describe doppler effect when observer is moving toward source
Definition
Stationary source emitting at a constant frequency. Observer moves towards the source at a constant velocity. Observer can claim he is at rest and source is approaching him at speed = speed of wave speed of obsever. This results in an apparent change in wavespeed.
Term
When the Doppler effect applies to light...
Definition
As speed of light is soooooo large compared to speed of observer or source the equation is simplified to this approximation.
Term
Used of Doppler effect
Definition
Measuring vehicle speeds. Measurement of blood flow.
Term
Polarised light
Definition
Light only oscillates in one plane
Term
Polarisation by reflection
Definition
When unpolarised light reflects off a non metallic surface- the reflected ray is partially polarised. Plane of polarisation is perpendicular to the reflecting surface THEREFORE resultant light is parallel to the reflecting surface
Term
Electron microscope
Definition
In order for objects to be resolved angular separation must be greater than 1.22y/b. minimum. The light used to resolve the object must be the same size or
smaller than the object.
Term
Brewster angle
Definition
The angle of incidence that causes the reflected ray to be 100% polarised and therefore the angle at which the angle between the reflected and refracted ray is 90
Term
Polariser
Definition
Polariser reduces light intensity by 50% to produce polarised light where light only oscillates in one plane.
Term
Analyser
Definition
determines if light is polarised.
Term
Optically active substance
Definition
Rotates the plane of polarisation
Term
Relationship between the concentration of a solution and polarisation of light
Definition
Increasing the concentration of solution increases the angle by which the plane of polarisation is rotated.
Term
How may polarisation be used in stress analysis?
Definition
Materials not normally optically active become so under stress. The degree of optical activation is proportional to the stress.
Term
LCD
Definition
Surface of pixels. Each pixel has liquid crystals between two glass plates. Thin slits on first glass plate so molecules align. Second glass plate same slits but perpendicular to slits in glass 1.
When voltage applied molecules align with electric field and pixel will be dark. No pd then bright.
Term
Electric potential difference
Definition
Work done per unit charge to move a small positive test charge between two points.
Term
Electronvolt
Definition
Work done when a charge equal to one electron charge is taken across a potential difference of one volt.
Term
Electric current
Definition
Rate of flow of charge.
Force per unit length between parallel current - carrying conductors.
Term
Resistance
Definition
Ratio of potential difference to current
Term
Ohms law
Definition
States that the voltage is directly proportional to the current
Term
EMF
Definition
Total work done in moving a unit charge completely around the circuit.
Term
Internal resistance
Definition
Material of a cell causes resistance. Not perfect conductor. As the atoms vibrate energy loss in form of heat. Converted from electrical to heat
Term
Ideal ammeters
Definition
Measures current therefore no resistance
Term
Ideal voltmeter
Definition
Voltmeter measures voltage therefore in order to measure you need all the volts therefore to use all volts therefore very high resistance
Term
Potential divider. Giving ratio of v(out) to v(in)
Definition
Used to switch on and off secondary circuits as environmental conditions change.
Two non ohmic resistors connected in series.
Current through each resistor is equal. Secondary circuit is connected before and after the first resistor. Second resistor acts as a variable resistor. R1/R1 R2
Term
Potential divider r2 decreases then...
Definition
V out increases
Term
Resistance increases on r2 in potential divider.
Definition
Then v out decreases
Term
LDR's
Increase in light = ... In resistance
Definition
Decreases
Term
Thermistor
Increase in temp = ... in resistance
Definition
Decrease
Term
Derive P=IV
Definition
P=W/T
W=VQ
P=VQ/T
Q/T=I
Therefore
P=IV
Term
Neutrons in nuclear reactors
Definition
Sustain nuclear reactions.
Chain reaction.
U235 can only capture slow neutrons.
Term
Critical mass
Definition
In order for reaction to occur need a certain minimum mass of uranium 235 otherwise neutrons escape without causing further reactions.
Term
Controlled nuclear production v uncontrolled.
Definition
Controlled Nuclear fission = power production
Uncontrolled nuclear fission = nuclear weapons
Term
Fuel enrichment
Definition
Increases the percentage of u235 to 3% or more
Term
Main energy transformations in nuclear
Definition
Nuclear - kinetic - thermal - kinetic - electrical
Term
Role of moderator
Definition
Material surrounding fuel rods
Reduces speed of neutrons by colliding with neutrons. so that chance of initiating fission is higher.
Material = graphite/ water
Term
Control rods
Definition
Absorb excess neutrons( too many can lead to excess energy released). Can be removed and reinserted upon need.
Term
Role of heat exchanger (nuclear)
Definition
Heat exchanger turns water to steam at high temp and pressure.


Steam used to turn turbines
Term
Describe how some reactors are used to produce plutonium
Definition
Uranium 238 (92) absorbs neutron = uranium 239 (92)
(Beta - decay)*2
To give Pu(239-94)
SHOET VERSION:
U238 present - most abundant
U238 absorbs fast proton to produce plutonium
Term
Why is uranium to plutonium important ?
Definition
1. U238 = non fissionable
Term
Safety issues
Definition
Products = highly reactive, long half lives
Term
Problems associated with nuclear fusion
Definition
Maintaining and controlling a high temp and high density plasma environment.
Term
Outline what happens in nuclear fusion
Definition
Deuterium and tritium = helium
Term
State the meaning of Q
Definition
Energy transferred to or from the system
Term
State the meaning of W
Definition
Work done by or on gas.
Term
Malus's law
Definition
Calculates intensity of polarised light given angle of polariser and maximum intensity
Term
Hooke's law
Definition
States that the force exerted on a spring is directly proportion to the displacement.
F = -kx
Term
Period is equal to
Definition
2pi/w
W= angular frequency of motion
Term
Is the period of an oscillation affected by its amplitude?
Definition
No. T = 2pi/2
T= root (length of string/ g) * 2pi
Term
Voltage in series.
Definition
Voltage is potential difference therefore in order to calculate must be between two points. PD is not same across circuit.
In series v total= I(r1 r2 etc).
Term
Current in series
Definition
Same across whole of circuit - rate does not change.
I= Vtotal/ R total
Term
Voltage in parallel
Definition
Voltage is same across whole of circuit. Do not add voltage etc
Term
Current in parallel
Definition
Current = total current in parallel =
Current in series.
Term
Describe inducing of an emf by relative motion between a conductor and a magnetic field.
Definition
Picture mag field going into page.
Wire is moved down horizontally along page.
Therefore force is to right and electrons are pushed to right - electrons moving to right = current moving to left.
Current is induced therefore emf is induced
Term
Derive formula for emf induced in a straight conductor moving in a magnetic field.
Definition
Emf=work done per unit charge
W= f*l
F=qvb
W= qvbl
E= qvbl/q
=blv
Term
Magnetic flux: intuitive and IB def
Definition
Intuitive: no of field lines ( which do not exist) passing through an area
IBdef: product of normal component of magnetic field strength and area of loop
Term
Magnetic flux linkage:
Definition
product of normal component of magnetic field strength, area of loop and number of turns of wire in loop
Term
State faraday's law
Definition
= induced emf is equal to the negative rate of change of magnetic flux.
Term
Lenz's law
Definition
Induced emf will be in direction that opposes change in magnetic flux that created the current
Term
Emf induced in a coil rotating within a uniform magnetic field is... If rotation is at constan speed
Definition
Sinusoidal
Term
What is meant by root mean squared value of an alternating current or voltage?
Definition
The value of the direct current or voltage that dissipates power in a resistor at the same rate.
Term
The rms value is also known as the...
Definition
Rating
Term
Possible risks of living and working near power lines.
Definition
Current evidence suggest low freq radiation does not harm genetic material.
Not fully understood.
Risks are dependent upon current, frequency and length of exposure.
Term
Efficiency of modern natural gas power station
Definition
50%
Term
What increases the current registered by galvanometer connected to loop of wire exposed to changing magnetic flux.
Definition
- increase speed of magnet
- increase number of turns of wire
- increase area of loop of wire
- magnet moves perpendicular to plane of loop
Term
How do you determine direction of magnetic field in solenoid?
Definition
Use right hand thumb rule. Direction of magnetic field is the same as the direction of the current.
Term
In order for two variables to be proportional
Definition
Must be -linear
- go through 0,0
Term
Doubling the frequency of ac generator does what...
Definition
Doubles peak voltage and doubles frequency of current/voltage
Term
Thermal energy may be completely converted to work in a single process BUT
Definition
Continuous conversion is a cyclic process - some energy will be transferred to surroundings.
Term
Photovoltaic cell - describe energy transfers and uses of device
Definition
Converts sunlight to electricity.
Use semiconductors
Valence electrons - charge - current created
Used in calculators, now solar power
Term
Solar heating panel
Definition
Sunlight used to heat water or air for use in house .
Term
Percentage of energy sources: coal
Definition
39%
Term
Percentage of energy sources: gas
Definition
19%
Term
Percentage of energy sources: nuclear
Definition
17
Term
Percentage of energy sources: hydro
Definition
16
Term
Percentage of energy sources: oil
Definition
7
Term
Efficiency of oil power station
Definition
40%
Term
Efficiency of gas power station
Definition
59-80%
Term
Outline historical and geographical reasons for the widespread use of fossil fuels.
Definition
Industrialisation = higher rate of energy use
As coal has a much higher energy density than coal.
Started to use coal - widespread use was there because hard to mine.
Built industry near fossil fuels - minimise cost of transportation .
Term
Adv and disadvantage of transportation and storage of fossil fuels.
Definition
Disadvantages: expensive to transports as large masses, need
Extensive storage facilities as high volume. Oil leaks
Advantages: coal is inert - will not react.
Term
Environmental problems associated with recovery of fossil fuels.
Definition
Produces large no of toxic substances. High in sulphur content - ( acid deposition).
Traces of heavy metals = eutrophication.
Term
Neutrons used in nuclear fission are of what energy
Definition
~1ev
Low energy
Term
Reasons for seasonal and regional variations in the solar power per unit area of earth's surface.
Definition
Earth not constant distance from earth and power output not constant.
Due to latitudes - higher latitudes energy is spread over a greater area.
Term
Name different hydroelectric schemes and outline how they work.
Definition
Water storage in lakes - as high elevation as possible to maximise pe.
Pump storage system: water that flows to lower heights is pumped back by generators of plant.
Tidal storage: flow of water during a tide turn turbines - producing electricity.
Term
Main energy transformations in hep
Definition
Potential to kinetic to electrical
Term
Basic features of a
Wind generator and main energy transformations
Definition
Wind turns blades.
Turns turbine = electrical energy.
Solar - kinetic - kinetic rotation - electrical
Term
Determine power that may be delivered by a wind generator assuming that the wind kinetic energy is completely converted into mechanical energy. Is this possible and why?
Definition
Use power and ke formula.
Input mass of wind - rem cylinder shape.
Term
Describe principle of operation of an oscillating water column.
Definition
As wave approaches air rises and pushes air - air passes through turbine and turns it.
As trough of wave falls draws air from atmosphere - turns turbine as air moves back down to fill vacuum.
Term
When determining power per unit length of wavefront what equation and under what assumptions.
Definition
power per unit length = (A*2pgv)/2
rectangular wave profile
Term
Idea behind energy balance
Definition
Earth is like a black body as constant average temperature so energy in must equal energy out.
Term
Write energy balance equation
And understand it
Definition
P= (1-a)IA
Term
Emissivity
Definition
Ratio of power emitted by a black body to power emitted if it were a black body.
Term
Relationship between gravitational field strength and gravitational potential
Definition
Field strength =
Negative gradient of potential
Term
Significance of resolution in development of CD/DVDs
Definition
Increased resolution = smaller wavelength needed as angular separation needed gets smaller.
Smaller wavelength = smaller pot depth = fit more
Term
Significance of resolution in radio telescopes.
Definition
Since wavelength of radio telescopes is very large to get good resolution need large slit width = large aperture. Need large dish like receivers.
Term
Significance of resolution in electron microscope
Definition
Wavelength of light must be very small or same order of magnitude as object.
Term
Power dissipated in conductor
Definition
=IV
used to perform work or lost as thermal energy
Term
When calculating activity / half life etc. time is in....
Definition
just use same units of time all the way through. Therefore all seconds or all minutes etc
Term
Explain how greenhouse gas causes global warming?
Definition
1. GG will absorb infrared radiation because infrared frequency is = natural frequency of oscillation therefore resonance occurs.
2. Re radiate energy in RANDOM directions which prevents energy escaping into space.
Term
Magnitude of mass of earth
Definition
10^50
Term
Relationship between emf induced and magnetic flux:
Definition
Emf: gradient of flux
Term
Why does a photon have momentum
Definition
P = h/wavelength.
They have momentum
No rest mass but have momentum
Term
Energy transformations in oscillating water and column
Definition
Initial = kinetic
Then potential = vacuum
Then kinetic.
Term
Energy to electrical
Definition
Must mention electrical generator
Term
What is meant by a pixel
Definition
Small area on a
Semiconductor chip. Smallest part of the chip that can detect a photon.
Term
How does light incident on CCD
Cause electric signal
Definition
Photons = emission of electron
= Change in potential difference
Potential difference correspond to light intensity.
Term
Advantages of CCD
Definition
Greater quantum efficiency. Sensitive to wider range of em spectrum. Processing time of image = shorter.
Term
State why only average kinetic energy of molecules of an ideal gas is related to the internal energy of the gas.
Definition
Potential energy not used.
No forces between molecules in an ideal gas.
Gas speeds vary so need to take an average.
Term
Pv diagrams constant temp = what type of line and q = 0 what line
Definition
= curved
= straight
Term
Stanley diagram how do you calculate efficiency
Definition
Using width not area
Term
Mass of sun
Definition
10^30
Term
Mass of earth
Definition
10^24
Term
Age of universe
Definition
10^17 s
Term
Distance of solar system
Definition
10^13m
Term
Radius of earth
Definition
10^7m
Term
Size of cell
Definition
10^-5 m
Term
Size of hydrogen atom
Definition
10^-10m
Term
Size of nucleus
Definition
10^-15m
Term
Size of proton
Definition
10^-17m
Term
Magnitude of magnitude of electric field between two plates.
Definition
Constant.
Term
Increasing distance between slit and screen - increases / decreases distance between central maxi and first minimum
Definition
Increases
Term
Capacitance
Definition
Q/v
Term
Electromotive force
Definition
Work done per unit charge supplied by the supply
Term
Travelling / progressive wave
Definition
A wave that transfers energy between two points in medium.
Term
Right hand rule for...
Definition
Ions
Term
Two wires same direction of current will...why?
Definition
Attract.
Current in one wire produces mag field in region of adjacent turn.
Thus gives force - and attraction occurs.
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