SecondaryCode 5054
Physics
63 topics and 270 objectives, each one something you should be able to do.
Written by Kindred in its own plain words. Your syllabus is still the official list, so check it for anything exact.
What this subject asks you to be able to do
1.1Physical quantities and measurement techniques8 objectives
- outline the method for taking a range of length readings to a suitable precision with tapes, rulers and micrometers, including how to read the scale of an analogue micrometer
- describe the procedure for using a measuring cylinder to find a liquid's volume, and for finding a solid's volume through displacement
- outline the procedure for measuring an assortment of time intervals by means of clocks and digital timers
- Determine the average of a small distance, and of a short time interval, by measuring many of them together (including a pendulum's period of oscillation)
- Understand that a scalar quantity is described by its magnitude (size) only, but a vector quantity needs both magnitude and direction
- know that distance, speed, time, mass, energy and temperature are scalars
- Know that each of these is a vector quantity: displacement, force, weight, velocity, acceleration, momentum, electric field strength and gravitational field strength
- work out the resultant of a pair of vectors at right angles, by calculation or graphically
1.2Motion13 objectives
- Define speed as how far something travels in each unit of time, and define velocity as how much its displacement changes in each unit of time
- Recall the equation speed = distance / time and use it in calculations
- Recall average speed = total distance travelled / total time taken and use this equation when calculating
- Define acceleration as the change in velocity in each unit of time; recall acceleration = change in velocity / time taken and use this equation
- Give the meaning of uniform acceleration and of non-uniform acceleration, and outline instances of each
- Know that deceleration means a negative acceleration, and apply this idea when calculating
- Draw sketches and plots of distance–time and speed–time graphs, and interpret them
- Determine, from the way a distance–time graph is shaped, the times at which an object is (a) stationary (b) travelling at a constant speed (c) accelerating (d) decelerating
- Determine, from the way a speed–time graph is shaped, the times at which an object is (a) stationary (b) travelling at a constant speed (c) travelling with a constant acceleration (d) travelling with an acceleration that changes
- State that, close to the Earth's surface, the acceleration of free fall g of an object stays roughly constant, at about 9.8m/ s2
- Calculate an object's speed by finding the gradient of its distance–time graph
- Work out the distance travelled, by finding the area under a speed–time graph, for motion at constant speed or with constant acceleration
- Find acceleration by way of the gradient of a speed–time graph
1.3Mass and weight7 objectives
- State that mass gives a measure of how much matter an object contains when it is at rest relative to an observer
- State that an object's mass opposes any change in its state of motion or rest (inertia)
- Know that a beam balance or an equal-arm balance can be used to compare weights, and so also masses
- Describe the procedure for working out mass by means of an electronic balance
- Describe how a force meter is used to measure weight
- Define gravitational field strength as the force on each unit of mass; recall gravitational field strength = weight / mass and use it, and know that it equals the acceleration of free fall
- State that a gravitational field is a space in which a mass is acted on by a force arising from gravitational attraction.
1.4Density2 objectives
- define density as the mass contained in each unit of volume; state and apply the equation density = mass / volume
- Describe how to find the density of three things, a liquid, a solid with a regular shape and a solid with an irregular shape that sinks in a liquid (finding its volume by displacement), including the calculations needed
1.5.1Balanced and unbalanced forces8 objectives
- Identify the various kinds of force and use them, including contact force, friction, drag, air resistance, weight (gravitational force), thrust (driving force), tension (elastic force), magnetic force and electrostatic force
- Identify the forces that act upon a body, and sketch free-body diagram(s) showing them
- State Newton’s first law: unless a resultant force acts on it, an object stays at rest or keeps moving at constant speed in a straight line
- State that a force can change an object's velocity, either by changing the direction in which it moves or by changing its speed
- Determine the resultant when several forces (two or more) act along one straight line
- Recall resultant force = mass × acceleration and use this equation in calculations
- State Newton’s third law: whenever object A applies a force to object B, object B applies a force to object A that is equal in size and opposite in direction
- Know that Newton’s third law deals with forces that come in pairs, where both forces are the same type but act on different objects
1.5.2Friction5 objectives
- Describe friction as a force that can resist motion and can cause heating
- Understand how objects move under an unchanging weight or driving force, both with and without drag, including air resistance or resistance in a liquid
- Account for how an object comes to reach terminal velocity
- Define, for a vehicle in motion, its thinking distance, its braking distance and its stopping distance
- Explain the ways in which thinking distance and braking distance can be altered by a range of factors, including speed, tiredness, alcohol, drugs, load, tyre surface and road conditions
1.5.3Elastic deformation4 objectives
- Know that forces can alter the dimensions and form of an object.
- Define the spring constant as the force for each unit of extension; recall spring constant = force / extension and use it in calculations
- Plot and sketch load–extension graphs of an elastic solid and interpret them, and describe the experimental procedures used to produce them
- Define the limit of proportionality of a load–extension graph, use the term, and identify where this point lies on the graph (you do not need to understand the elastic limit)
1.5.4Circular motion1 objective
- Describe, in qualitative terms, how a body moves along a circular path when a force perpendicular to its direction of motion acts on it, covering: (a) the speed rising as the force grows, provided mass and radius are fixed; (b) the radius shrinking as the force grows, provided mass and speed are fixed; (c) a larger mass needing a bigger force so that speed and radius stay unchanged
1.5.5Turning effect of forces4 objectives
- Describe a force's moment as a way of measuring its turning effect, and give examples from everyday life
- Define a force's moment by moment = force × perpendicular distance to the pivot; recall this equation and use it in calculations
- State the principle of moments and apply it whenever an object is in equilibrium
- Describe an experiment that checks whether the principle of moments holds
1.5.6Centre of gravity3 objectives
- give the meaning of the term centre of gravity
- outline the procedure for locating, with a plumb line, the point at which the centre of gravity sits in a plane lamina
- outline qualitatively how the location of the centre of gravity influences how stable simple objects are
1.6Momentum4 objectives
- Define momentum by the product mass × velocity; recall p = mv and use this equation
- Define impulse as force × the length of time over which the force acts; remember and make use of the equation impulse = FΔt = Δ(mv)
- Apply conservation of momentum to tackle straightforward questions confined to one dimension
- Define resultant force as how much momentum changes in each unit of time; recall resultant force = change in momentum / time taken F = ∆p / ∆t and use this equation
1.7.1Energy5 objectives
- State that energy can be held in kinetic, gravitational potential, chemical, elastic (strain) and nuclear stores, and also in electrostatic and internal (thermal) stores
- Describe how energy passes from store to store across events and processes, including cases of transfer through forces (mechanical work done), electrical currents (electrical work done), heating, and through electromagnetic, sound and other waves
- Know the principle of conservation of energy, and apply it whenever energy passes from one store to another in an event or process
- Recall the kinetic energy equation Ek = 1/2 mv² and use it in calculations
- Recall ΔEp = mgΔh, which gives the change in gravitational potential energy, and use it in calculations
1.7.2Work1 objective
- Recall and apply the equation for work: work done = force × distance covered in the same direction as the force, W = Fd
1.7.3Energy resources3 objectives
- Name the renewable and non-renewable sources of energy
- Describe how useful energy can be extracted, or electricity generated, using each of these: (a) the chemical energy held in fossil fuels; (b) the chemical energy held in biofuels; (c) hydroelectric resources; (d) solar radiation; (e) nuclear fuel; (f) geothermal resources; (g) wind; (h) tides; (i) sea waves, including mention of a boiler, turbine and generator wherever each is used
- Describe, for each method, its advantages and disadvantages, limited to whether it is renewable, whether and when it is available, and what impact it has on the environment
1.7.4Efficiency1 objective
- Define efficiency as a percentage, (a) in terms of energy, (%) efficiency = (useful energy output) / (total input energy) × 100%, and (b) in terms of power, (%) efficiency = (useful power output) / (total power input) × 100%; recall these two equations and use them in calculations
1.7.5Power1 objective
- Define power in two ways, as the work done in each unit of time and as the energy transferred in each unit of time; recall the equations (a) power = work done / time taken P = W / t and (b) power = energy transferred / time taken P = ∆E / t, and use them
1.8Pressure6 objectives
- Define pressure as the force acting per unit area; remember and apply the relationship pressure = force / area p = F / A
- Describe the manner in which pressure depends on force and area, drawing on everyday examples
- State that the force from pressure at a surface always acts at right angles to that surface, and describe an experiment that shows this
- Describe how a liquid barometer can be used to find atmospheric pressure from the height reached by its liquid column
- Describe in quantitative terms how the pressure below the surface of a liquid varies according to its depth and the liquid's density
- Recall the equation for how pressure changes below the surface of a liquid, pressure change = density × gravitational field strength × height change, or ∆p = ρg∆h, and use it
2.1.1States of matter2 objectives
- Understand what sets solids, liquids and gases apart from one another
- Know the names given to the transitions of state among solids, liquids and gases (changes going straight from gas to solid or from solid to gas are not required)
2.1.2Particle model5 objectives
- Describe, qualitatively, how the particles in solids, liquids and gases are arranged, linking each state's properties to the forces between its particles, the distances between them and the way they move (atoms, molecules, ions and electrons)
- Describe how the motion of particles is related to temperature, including the idea of a lowest possible temperature (−273°C), called absolute zero, at which particles have the least kinetic energy
- Describe how a gas creates pressure, and how that pressure changes, through the forces produced when particles strike surfaces, giving a force per unit area
- Explain qualitatively, using particles, the link between: (a) pressure and temperature when volume is constant; (b) volume and temperature when pressure is constant; (c) pressure and volume when temperature is constant
- Recall and use the equation p1 / V1 = p2 / V2, including a graph that displays how pressure and volume of a gas relate when its temperature is constant
2.2.1Thermal expansion of solids, liquids and gases3 objectives
- Explain how thermal expansion is put to use and what it leads to in everyday settings, including the liquid-in-glass thermometer
- Account for the thermal expansion of solids, liquids and gases using the movement and layout of their particles, and state how the amount of expansion compares across solids, liquids and gases
- Convert a temperature from kelvin to degrees Celsius, and the reverse; state and apply the relationship T (in K) = θ (in °C) + 273
2.2.2Specific heat capacity4 objectives
- Know that a rise in an object's temperature makes its internal energy go up
- Describe a rise in an object's temperature as a rise in the average kinetic energy of all the particles it contains
- Define specific heat capacity as the energy needed to raise the temperature of each unit of mass by one unit; recall specific heat capacity = energy change / (mass × temperature change), c = ∆E / (m∆θ), and use it
- Describe experiments that measure a solid's specific heat capacity and also a liquid's
2.2.3Melting, boiling and evaporation7 objectives
- Describe melting, solidification, boiling and condensation as processes in which energy is transferred without the temperature changing
- Know the temperatures at which water melts and boils under standard atmospheric pressure
- Outline the ways in which boiling and evaporation differ
- Describe evaporation in terms of more energetic particles making their escape from a liquid's surface
- Outline how the temperature, the surface area and the movement of air across a surface influence evaporation
- Account for evaporation producing a cooling effect
- Describe latent heat as the energy a substance needs in order to change state, and explain it using how particles behave and the forces between them
2.3.1Conduction2 objectives
- Describe experiments that set apart good thermal conductors from poor ones
- Describe how heat is conducted through every solid in terms of vibrations of atoms or molecules in the lattice, and also in terms of free (delocalised) electrons moving through metallic conductors
2.3.2Convection1 objective
- account for convection in liquids and gases through changes in density, and describe experiments that demonstrate it
2.3.3Radiation5 objectives
- Describe how thermal energy is transferred by infrared radiation, and understand that such transfer does not need a medium.
- Describe how the colour of a surface (black or white) and its texture (dull or shiny) affect how much infrared radiation it emits, absorbs and reflects
- Describe how an object's surface temperature and surface area affect the rate at which it emits radiation
- Describe experiments that distinguish good emitters of infrared radiation from bad ones.
- Describe experiments that distinguish good absorbers of infrared radiation from bad ones.
2.3.4Consequences of thermal energy transfer1 objective
- Explain how everyday situations draw on conduction, convection and radiation, including: (a) warming items such as kitchen pans (b) warming a room through convection (c) taking temperature readings with an infrared thermometer (d) employing thermal insulation to keep a liquid at a steady temperature and to lessen the thermal energy transfer taking place in buildings
3.1General properties of waves11 objectives
- Know that the transfer of energy by waves happens without any transfer of matter
- Describe what wave motion means, using the examples of ropes and springs that vibrate and experiments with water waves
- Describe a wave's characteristics by reference to wavefront, wavelength, frequency, crest (peak), trough, amplitude and wave speed
- Define these terms: (a) frequency, the number of wavelengths passing a given point in each unit of time (b) wavelength, the distance from one point on a wave to the next identical point, such as from one crest to the next (c) amplitude, the greatest distance from the mean position
- Recall wave speed = frequency × wavelength, written v = f λ, and use this equation
- Know that in a transverse wave the vibrations are at right angles to the direction in which energy is transferred, and give examples such as electromagnetic radiation, water-surface waves and seismic S-waves (secondary)
- Understand that in a longitudinal wave the vibration is parallel to the direction in which energy is transferred, and state examples such as sound waves and seismic P-waves (primary)
- Describe the ways in which waves may be subject to: (a) reflection off a plane surface (b) refraction caused by a change in speed (c) diffraction when passing through a gap
- Outline the influence that wavelength and the size of a gap have on diffraction through that gap
- Describe how a ripple tank can be used to show: (a) waves reflecting off a plane surface (b) waves refracting where a change in depth changes their speed (c) waves diffracting through a gap (d) waves diffracting at an edge
- Outline the effect that wavelength has on diffraction at an edge
3.2.1Reflection of light4 objectives
- Define the normal, the angle of incidence and the angle of reflection, and use each of these terms
- Describe a practical investigation that demonstrates the law of reflection
- Describe an experiment to find where a plane mirror forms an optical image and what the image's characteristics are (the same size as the object, as far from the mirror as the object is, and virtual)
- State that when light is reflected the angle of incidence equals the angle of reflection, and apply this to constructions, measurements and calculations
3.2.2Refraction of light6 objectives
- Define normal, angle of incidence and angle of refraction, then apply these terms
- Define refractive index n by the equation n = sin i / sin r; recall this equation and use it
- Describe an experiment showing how light is refracted by transparent blocks of various shapes
- Define what is meant by the critical angle and by total internal reflection; recall n = 1 / sin c and apply this equation in calculations
- Describe experiments in which both internal reflection and total internal reflection can be seen
- Describe what optical fibres are used for, especially in telecommunications, and state the benefits they bring in each case
3.2.3Thin lenses7 objectives
- Describe how a parallel light beam is affected by a converging thin lens and by a diverging thin lens
- Define the focal length, the principal axis and the principal focus (focal point), and use these terms
- Draw ray diagrams to show a converging lens producing real and virtual images, and know that a real image comes from rays that converge while a virtual image comes from rays that diverge
- Define linear magnification as an image's length divided by the object's length; recall linear magnification = length of image / length of object and use this equation
- Outline the way in which a single lens serves as a magnifying glass
- Draw ray diagrams showing how images are formed in a normal eye, in a short-sighted eye and in a long-sighted eye
- Describe how long-sightedness is corrected with a converging lens and short-sightedness with a diverging lens
3.2.4Dispersion of light2 objectives
- Describe the dispersion of light, taking as an example what happens when white light is refracted by a prism made of glass
- Know the seven traditional colours of the visible spectrum ordered by frequency and also by wavelength
3.3Electromagnetic spectrum4 objectives
- Know the main regions of the electromagnetic spectrum, ordered both by frequency and by wavelength
- Know that all electromagnetic waves travel at 3.0 × 108 m/s in (a) a vacuum, and that in (b) air this speed is roughly equal to the vacuum value
- Describe the part each of the following regions plays in the applications given: (a) radio waves – communicating by radio and television, and astronomy (b) microwaves – microwave ovens, Bluetooth, mobile (cell) phones, television by satellite (c) infrared – thermal imaging, intruder alarms, remote controllers, optical fibres, electrical appliances in the home (d) visible light – seeing, and photography (e) ultraviolet – sterilising water, marking for security, spotting counterfeit bank notes (f) X-rays – imaging for medical purposes in hospitals, security scanners, killing cancerous cells, engineering uses such as finding cracks in metal (g) gamma rays – medical treatment that detects and kills cancerous cells, sterilising food and medical equipment, engineering uses such as finding cracks in metal
- Describe the harm electromagnetic radiation can do, including: (a) too much exposure heating soft tissues and causing burns (b) the ionising effects of ultraviolet, which can lead to skin cancer and cataracts, and of X-rays and gamma rays, which can lead to cell mutation and cancer
3.4Sound13 objectives
- Outline how vibrating sources generate sound
- Describe the longitudinal character of sound waves, along with the compressions and rarefactions they contain
- Give the approximate band of frequencies humans can hear, from 20Hz to 20000Hz
- Explain why a vacuum cannot carry sound waves, and describe an experiment showing that this is so
- Outline how altering the amplitude and frequency of sound waves changes their loudness and pitch
- Outline how different sound sources give rise to sound waves of differing qualities (timbres), as revealed by the shapes of oscilloscope traces
- Describe an echo as a sound wave that has been reflected
- Outline simple experiments that demonstrate the reflection of sound waves
- Describe a method that uses measurements of distance and time to find the speed at which sound travels through air
- Know that sound travels through air at a speed of roughly 330–350 m/s.
- Know that, generally, sound moves more quickly through solids than liquids, and more quickly through liquids than gases.
- Define ultrasound: sound whose frequency lies above 20kHz.
- Describe how ultrasound is put to use in cleaning, prenatal and other medical scanning, and in sonar (including working out depth or distance using time and wave speed)
4.1Simple magnetism and magnetic fields10 objectives
- Describe how magnetic poles exert forces on one another, and how magnets exert forces on magnetic materials, including using the terms N pole (north pole), S pole (south pole), attraction, repulsion, magnetised and unmagnetised
- Describe induced magnetism
- State how magnetic materials differ from non-magnetic ones
- State the ways in which temporary magnets, formed from soft iron, differ from permanent magnets, which are formed from steel.
- Describe a magnetic field as a region of space in which magnetic poles have forces exerted on them
- Describe how magnetic field lines are plotted using iron filings or a compass, and how a compass is used to find the direction of the magnetic field
- Draw the magnetic field lines that surround a bar magnet, showing both their pattern and their direction
- State that, at any point, the magnetic field points in the same direction as the force felt by the N pole of a magnet placed there
- Understand that the strength of a magnetic field, relative to others, is shown by how closely the magnetic field lines are spaced.
- Describe the ways in which permanent magnets and electromagnets are put to use.
4.2.1Electrical charge10 objectives
- State that two kinds of charge exist, positive and negative, and that coulombs are the unit used to measure charge.
- State that like charges repel each other, while unlike charges attract each other
- Describe experiments showing that friction can cause electrostatic charging
- Explain that when solids are charged by friction, the only thing transferred is negative charge (electrons).
- Describe an electric field as a region of space in which electric charges have forces exerted on them
- State that, at any point, an electric field line points in the direction of the force that a positive charge would feel there
- Describe simple patterns of electric field, including which way the field points: (a) near a point charge (b) near a charged conducting sphere (c) in the space between two parallel conducting plates with opposite charges (end effects will not be tested)
- State instances of conductors and insulators of electricity.
- Describe an experiment that allows conductors and insulators to be told apart.
- Recall and apply a simple electron model to account for how conductors differ from insulators.
4.2.2Electrical current6 objectives
- Define electric current as the amount of charge that flows past a point in each unit of time; recall electric current = charge / time, I = Q / t, and use this equation
- Describe how metals conduct electricity through the movement of free electrons
- Know that the unit for current is the amp (amperes), and that an amp corresponds to one coulomb per second (C/s)
- understand what separates direct current (d.c.) from alternating current (a.c.)
- State that conventional current runs from the positive terminal to the negative one, whereas free electrons move from negative towards positive
- outline how analogue and digital ammeters are used when they have different ranges
4.2.3Electromotive force and potential difference6 objectives
- Define e.m.f. (electromotive force) as the electrical work a source does to move a unit charge all the way round a complete circuit; recall e.m.f. = work done (by a source) / charge, E = W / Q, and use this equation
- Define p.d. (potential difference) as the work done by each unit of charge as it passes through a component; recall p.d. = work done (on a component) / charge, V = W / Q, and use this equation
- Know that the volt is the unit of both e.m.f. and p.d., and that one volt is one joule per coulomb (J/C)
- Outline how analogue and digital voltmeters, which cover different ranges, are employed
- Work out the overall e.m.f. when a number of sources are connected in series
- State that when identical sources are linked in parallel, their e.m.f. is the same as the e.m.f. of a single source
4.2.4Resistance6 objectives
- Recall resistance = p.d. / current, R = V / I, and use this equation
- Describe an experiment in which a voltmeter and an ammeter are used to find resistance, then carry out the suitable calculations
- Recall that a wire's resistance is directly proportional to its length and inversely proportional to its cross-sectional area, and use these relationships
- Give Ohm's law, including the requirement that temperature stays constant
- Sketch, and account for, the current–voltage graphs of a resistor whose resistance stays constant, a filament lamp and a diode
- Describe how raising the temperature of a resistor, such as the filament of a filament lamp, affects its resistance
4.3.1Circuit diagrams and circuit components1 objective
- Draw and interpret circuit diagrams that use any of these components: cells, batteries, power supplies and generators; switches, relays and fuses; resistors (fixed and variable), thermistors (NTC only), light-dependent resistors (LDRs) and potential dividers; diodes and light-emitting diodes (LEDs); lamps, heaters, motors and magnetising coils; transformers; ammeters, voltmeters and oscilloscopes; and know what each component does in a circuit
4.3.2Series and parallel circuits4 objectives
- Recall and use the following facts in calculations: (a) the current is identical at every position in a series circuit (b) the currents flowing into a junction in a parallel circuit add up to the same total as the currents flowing out of it (c) in a series circuit, the overall p.d. across the components equals the total of the separate p.d.s across each component (d) the p.d. across a set of resistances connected in parallel matches the p.d. across any single branch of that set
- Calculate, for two or more resistors in series, their combined resistance
- Calculate, for two resistors connected in parallel, their combined resistance
- Work out the current, voltage and resistance for sections of a circuit or for the complete circuit
4.3.3Action and use of circuit components3 objectives
- Describe how light-dependent resistors and negative temperature coefficient (NTC) thermistors work, and explain how they are used as input sensors
- outline how a variable potential divider operates
- Recall and apply the equation R1/R2 = V1/V2 for a pair of resistors acting as a potential divider
4.4.1Uses of electricity5 objectives
- Give everyday applications of electricity, including heating, lighting, charging batteries and running motors and electronic systems
- Give the benefits of wiring lamps in parallel within a lighting circuit
- Recall and apply the formula power = current × voltage, written as P = IV
- Recall and apply the expression energy = current × voltage × time, written in the form E = IVt
- Define the kilowatt-hour (kWh) and work out the cost of running electrical appliances when energy is given in kWh
4.4.2Electrical safety6 objectives
- State the hazards, when a mains supply is being used, of: (a) insulation that is damaged (b) cables that overheat (c) damp conditions (d) too much current caused by overloading plugs, extension leads, and single and multiple sockets
- Explain how trip switches and fuses work and what they are for, and select suitable values for the ratings of fuses and the settings of trip switches
- Explain what takes place when a live wire makes contact with an earthed metal casing
- Account for why an electrical appliance's outer casing has to be made non-conducting (double-insulated) or connected to earth
- Know that the three wires of a mains circuit are the live wire (or line wire), the neutral wire and the earth wire, and explain why the switch must sit in the live wire if the circuit is to be turned off safely
- Account for the reason fuses and circuit breakers are placed in the live wire
4.5.1Electromagnetic induction3 objectives
- Describe a practical investigation that shows electromagnetic induction in action
- State that an induced e.m.f. has a magnitude that depends on: (a) the rate at which the magnetic field changes or at which magnetic field lines are cut (b) how many turns the coil has
- State and use Lenz’s law: the current produced by an induced e.m.f. has an effect that opposes the change producing it; describe a way of demonstrating this law
4.5.2The a.c. generator2 objectives
- Describe a simple a.c. generator, of either the rotating-coil or the rotating-magnet type, and how slip rings and brushes are used where they are needed
- Draw and interpret plots showing e.m.f. varying with time in simple a.c. generators, and match the coil's orientation in the generator to the e.m.f. peaks, troughs and zeros.
4.5.3Magnetic effect of a current2 objectives
- Describe the magnetic field produced by a current in a straight wire and in a solenoid, giving its pattern and direction, and state how the field is affected when the current's magnitude or direction is changed
- Describe the way relays and loudspeakers make use of the magnetic effect of a current, and give examples of where they are applied
4.5.4Forces on a current-carrying conductor3 objectives
- Describe an experiment showing that a current-carrying conductor in a magnetic field has a force on it, including what happens when you reverse (a) the current (b) the field's direction
- Recall and use how the force, the magnetic field and the current are oriented relative to one another
- Describe the patterns of magnetic field between parallel conductors carrying currents, and relate them to the forces that act on those conductors (excluding the field of the Earth)
4.5.5The d.c. motor2 objectives
- Know that a coil carrying a current in a magnetic field can feel a turning effect, and that this turning effect becomes larger with: (a) more turns on the coil (b) a bigger current (c) a stronger magnetic field
- Describe the way an electric motor functions, including what the split-ring commutator and the brushes do
4.5.6The transformer4 objectives
- Describe how a simple iron-cored transformer is built and explain the principle that makes it work
- Apply the words primary and secondary, and step-up and step-down, to transformers
- Recall Vp/Vs = Np/Ns, in which P and S stand for primary and secondary, and use this equation
- Give the benefits of high-voltage transmission and account for why losses of power in cables fall as the voltage increases
4.6Uses of an oscilloscope2 objectives
- Describe what an oscilloscope is employed for when showing waveforms (its internal construction is not required)
- Describe the steps for taking readings of p.d. and short time intervals on an oscilloscope, making use of the Y-gain and the timebase
5.1.1The atom2 objectives
- Outline how an atom is built, with a positive nucleus at its centre and negative electrons circling around that nucleus
- Describe the evidence that alpha-particle scattering experiments give for: (a) a nucleus that is very small, with mostly empty space around it (b) a nucleus that holds most of the atom's mass (c) a nucleus with a positive charge
5.1.2The nucleus5 objectives
- Describe what the nucleus is built from, namely protons and neutrons
- Describe how an atom becomes a positive ion when it loses electrons, or a negative ion when it gains electrons
- Define two quantities, nucleon number (mass number) A and proton number (atomic number) Z, and use them to work out how many neutrons there are in a nucleus
- Explain what a nuclide is and apply the A ZX nuclide notation
- Explain the meaning of the word isotope, and state that it is possible for one element to have more than one isotope
5.2.1Detection of radioactivity5 objectives
- Describe how alpha particles (α-particles) are detected with a spark counter or a cloud chamber, and how beta particles (β-particles) (here β-particles means β−) and gamma radiation (γ-radiation) are detected with a Geiger-Müller tube and counter
- Apply count rates expressed either in counts / s or in counts /minute
- Understand the meaning of background radiation
- Know the sources that make up a significant part of background radiation, including: (a) radon, a gas found in the air (b) rocks in the ground, and building materials (c) what we eat and drink (d) cosmic rays
- Use background radiation measurements to work out a corrected count rate
5.2.2The three types of emission4 objectives
- Describe the emission of radiation by a nucleus as a spontaneous event whose direction is random
- Describe α-particles as helium nuclei, each made up of two protons together with two neutrons, β-particles as electrons that leave the nucleus at high speed, and γ-radiation as electromagnetic waves of high frequency
- Give, for α-particles, β-particles and γ-radiation: (a) the relative ionising effects each has (b) the relative penetrating powers each has
- Describe how α-particles, β-particles and γ-radiation are deflected in electric fields and in magnetic fields
5.2.3Radioactive decay2 objectives
- Know that in radioactive decay an unstable nucleus changes, which may lead to it emitting α-particles or β-particles and/or γ-radiation, and know that such changes happen spontaneously and at random
- apply decay equations written in nuclide notation to demonstrate the release of α-particles, β-particles and γ-radiation
5.2.4Fission and fusion3 objectives
- Describe fusion, in which two smaller nuclei unite to make one larger nucleus and give out energy, and recognise that fusion powers stars.
- Describe fission, the process in which a nucleus, such as uranium-235 (U-235), absorbs a neutron and then splits into daughter nuclei, giving off two or more neutrons and releasing energy
- Explain how the neutrons released in fission set up a chain reaction, and that in a nuclear reactor this reaction is kept under control, including what the coolant, moderators and control rods do
5.2.5Half-life3 objectives
- Define the half-life of a given isotope as the time needed for half of the nuclei in a sample of it, of any size, to decay; recall this definition and use it in calculations which may involve data from tables or decay curves
- Outline how carbon-14 (14C) is used to date objects
- Explain how the kind of radiation given out and the half-life of an isotope decide which isotope is chosen for uses including: (a) smoke alarms for fires in the home (b) irradiating food so that bacteria are killed (c) sterilising equipment with gamma rays (d) measuring and controlling how thick materials are, with the radiation chosen according to how it penetrates and is absorbed (e) diagnosing and treating cancer with gamma rays
5.2.6Safety precautions2 objectives
- Give the consequences that ionising nuclear radiations can have for living organisms, including cell death, mutations and cancer
- Explain how radioactive materials can be transported, handled and stored safely, referring to: (a) cutting down the time of exposure (b) raising the distance between the source and living tissue (c) using shielding to absorb radiation
6.1.1The Earth2 objectives
- Know that: (a) the Earth, which is a planet, goes round the Sun once in about 365 days (b) the Earth's orbit around the Sun is an ellipse that is nearly a circle (c) the Earth spins once on its tilted axis in about 24 hours (d) the Moon takes about one month to go round the Earth (e) light from the Sun takes about 500s to get to the Earth
- Define average orbital speed using v = 2πr / T, in which r stands for the orbit's average radius and T for the orbital period; recall this equation and use it
6.1.2The Solar System6 objectives
- Describe what the Solar System is made up of: (a) a single star, the Sun (b) each of the eight named planets, and the order in which they lie outward from the Sun (c) minor planets orbiting the Sun, including dwarf planets such as Pluto and the asteroids of the asteroid belt (d) moons, which orbit the planets (e) smaller bodies of the Solar System, including comets and natural satellites
- Analyse and interpret data on the planets' density, surface temperature, orbital period and orbital distance, and on the uniform gravitational field strength at each one's surface
- Know that gravitational field strength: (a) on a planet's surface relies on how massive the planet is (b) surrounding a planet falls off as one moves further from the planet
- Know that the majority of the Solar System's mass is held within the Sun, and that gravitational field strength on the Sun's surface exceeds that on the surfaces of the planets
- Know that it is the Sun's gravitational attraction that holds an object in orbit around it
- Know that the Sun's gravitational field gets weaker, and planets' orbital speeds drop, as distance from the Sun grows
6.2.1The Sun as a star2 objectives
- Know that the Sun is a medium-sized star composed largely of hydrogen and helium, giving off the greater part of its energy as radiation in the ultraviolet, visible and infrared parts of the electromagnetic spectrum
- Understand that nuclear reactions supply stars with their power, releasing energy, and that in stars which are stable the reactions join hydrogen nuclei together to form helium
6.2.2Stars2 objectives
- state that: (a) every galaxy consists of a huge number of stars, numbering in the billions (b) our star, the Sun, belongs to the Milky Way galaxy (c) the rest of the stars in the Milky Way lie at far greater distances from Earth than the Sun does (d) cosmic distances may be expressed in light-years, with a light-year being how far light moves through a vacuum in a single year
- Describe a star's life cycle: (a) stars form out of interstellar clouds of dust and gas containing hydrogen (b) a protostar is one of these clouds collapsing and heating up, pulled inward by its own gravitational attraction (c) once the outward force caused by the high temperature at its centre balances the inward force of gravity, the protostar has become a stable star (d) sooner or later every star runs short of the hydrogen that fuels its nuclear reaction (e) when most of the hydrogen at the centre has turned into helium, most stars swell into red giants, while stars of greater mass swell into red supergiants (f) a red giant that came from a lower-mass star becomes a planetary nebula, leaving a white dwarf in the middle (g) a red supergiant blows apart in a supernova explosion, producing a nebula of hydrogen together with newly formed heavier elements and leaving either a black hole or a neutron star in the middle (h) new stars, with planets orbiting them, may later form from the nebula a supernova leaves
6.2.3The Universe4 objectives
- Know that our galaxy, the Milky Way, is about 100000 light-years in diameter and is only one among many billions of galaxies in the Universe
- Describe redshift as the increase seen in the wavelength of electromagnetic radiation given out by stars and galaxies that are moving away
- Know that light from far-off galaxies displays redshift, and that the more remote a galaxy is, the larger its observed redshift and the greater its speed of movement away from the Earth.
- Describe, qualitatively, in what way redshift gives evidence backing the Big Bang theory.
Kindred builds your map from these, so you can see what you've covered and what's still to do.