# Shared Flashcard Set

## Details

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

Term
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
 MetalsDelocalised 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 collisions3. Volume of molecules are very small in comparison to the volume of the gasp4. 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 = zeroWork done = 0Change 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 energyChange in energy transferred = – change in the work done
Term
Definition
 Change in energy transfer = 0Change 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
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 gasesSolar 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 fromVostok 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
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 onCCD
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
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 = neutronBUT NO ELECTRON INNUCLEUS SO...Proton = neutron (opposite electron)Proton = neutron positron neutrino
Term
 Beta-
Definition
 Neutron = proton electron antineutrino
Term
Definition
 High dose: death, loss of coordination Med: damages stomach
Term
 Nucleus stability
Definition
 Dependent on the ratio of neutrons to protons
Term
Definition
 Random and spontaneous. Rate of decay decreases exponentially time
Term
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 particlesEg 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 theMax 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
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 smallerMore information stored
Term
 Diagram of GeigerMardsen.
Definition
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 orsmaller 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/TW=VQP=VQ/TQ/T=ITherefore 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 productionUncontrolled 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/2T= 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 chargeW= f*lF=qvbW= qvblE= 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
Definition
 product of normal component of magnetic field strength, area of loop and number of turns of wire in loop
Term
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
Definition
 Disadvantages: expensive to transports as large masses, needExtensive storage facilities as high volume. Oil leaksAdvantages: 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 aWind 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)/2rectangular 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 equationAnd 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
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 aSemiconductor chip. Smallest part of the chip that can detect a photon.
Term
 How does light incident on CCDCause electric signal
Definition
 Photons = emission of electron = Change in potential difference Potential difference correspond to light intensity.
Term
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
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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