Physics — A-Level

Physics 9702 — specification explorer

All 303 specification statements from the official Cambridge International specification, as printed.

Paper/unit applicability has not been derived for this course yet — the statements below are the parsed specification, as printed.

1. Physical quantities and units

1. Physical quantities

1.1.1understand that all physical quantities consist of a numerical magnitude and a unit
1.1.2make reasonable estimates of physical quantities included within the syllabus

2. SI units

1.2.1recall the following SI base quantities and their units: mass (kg), length (m), time (s), current (A), temperature (K)
1.2.2express derived units as products or quotients of the SI base units and use the derived units for quantities listed in this syllabus as appropriate
1.2.3use SI base units to check the homogeneity of physical equations
1.2.4recall and use the following prefixes and their symbols to indicate decimal submultiples or multiples of both base and derived units: pico (p), nano (n), micro ( μ ), milli (m), centi (c), deci (d), kilo (k), mega (M), giga (G), tera (T)

3. Errors and uncertainties

1.3.1understand and explain the effects of systematic errors (including zero errors) and random errors in measurements
1.3.2understand the distinction between precision and accuracy
1.3.3assess the uncertainty in a derived quantity by simple addition of absolute or percentage uncertainties

4. Scalars and vectors

1.4.1understand the difference between scalar and vector quantities and give examples of scalar and vector quantities included in the syllabus
1.4.2add and subtract coplanar vectors
1.4.3represent a vector as two perpendicular components

2. Kinematics

1. Equations of motion

2.1.1define and use distance, displacement, speed, velocity and acceleration
2.1.2use graphical methods to represent distance, displacement, speed, velocity and acceleration
2.1.3determine displacement from the area under a velocity–time graph
2.1.4determine velocity using the gradient of a displacement–time graph
2.1.5determine acceleration using the gradient of a velocity–time graph
2.1.6derive, from the definitions of velocity and acceleration, equations that represent uniformly accelerated motion in a straight line
2.1.7solve problems using equations that represent uniformly accelerated motion in a straight line, including the motion of bodies falling in a uniform gravitational field without air resistance
2.1.8describe an experiment to determine the acceleration of free fall using a falling object
2.1.9describe and explain motion due to a uniform velocity in one direction and a uniform acceleration in a perpendicular direction

3. Dynamics

1. Momentum and Newton’s laws of motion

3.1.1understand that mass is the property of an object that resists change in motion
3.1.2recall F = ma and solve problems using it, understanding that acceleration and resultant force are always in the same direction
3.1.3define and use linear momentum as the product of mass and velocity
3.1.4define and use force as rate of change of momentum
3.1.5state and apply each of Newton’s laws of motion
3.1.6describe and use the concept of weight as the effect of a gravitational field on a mass and recall that the weight of an object is equal to the product of its mass and the acceleration of free fall

2. Non-uniform motion

3.2.1show a qualitative understanding of frictional forces and viscous/drag forces including air resistance (no treatment of the coefficients of friction and viscosity is required, and a simple model of drag force increasing as speed increases is sufficient)
3.2.2describe and explain qualitatively the motion of objects in a uniform gravitational field with air resistance
3.2.3understand that objects moving against a resistive force may reach a terminal (constant) velocity

3. Linear momentum and its conservation

3.3.1state the principle of conservation of momentum
3.3.2apply the principle of conservation of momentum to solve simple problems, including elastic and inelastic interactions between objects in both one and two dimensions (knowledge of the concept of coefficient of restitution is not required)
3.3.3recall that, for an elastic collision, total kinetic energy is conserved and the relative speed of approach is equal to the relative speed of separation
3.3.4understand that, while momentum of a system is always conserved in interactions between objects, some change in kinetic energy may take place

4. Forces, density and pressure

1. Turning effects of forces

4.1.1understand that the weight of an object may be taken as acting at a single point known as its centre of gravity
4.1.2define and apply the moment of a force
4.1.3understand that a couple is a pair of forces that acts to produce rotation only
4.1.4define and apply the torque of a couple

2. Equilibrium of forces

4.2.1state and apply the principle of moments
4.2.2understand that, when there is no resultant force and no resultant torque, a system is in equilibrium
4.2.3use a vector triangle to represent coplanar forces in equilibrium

3. Density and pressure

4.3.1define and use density
4.3.2define and use pressure
4.3.3derive, from the definitions of pressure and density, the equation for hydrostatic pressure ∆ p = ρ g ∆ h
4.3.4use the equation ∆ p = ρ g ∆ h
4.3.5understand that the upthrust acting on an object in a fluid is due to a difference in hydrostatic pressure
4.3.6calculate the upthrust acting on an object in a fluid using the equation F = ρ gV (Archimedes’ principle)

5. Work, energy and power

1. Energy conservation

5.1.1understand the concept of work, and recall and use work done = force × displacement in the direction of the force
5.1.2recall and apply the principle of conservation of energy
5.1.3recall and understand that the efficiency of a system is the ratio of useful energy output from the system to the total energy input
5.1.4use the concept of efficiency to solve problems
5.1.5define power as work done per unit time
5.1.6solve problems using P = W / t
5.1.7derive P = Fv and use it to solve problems

2. Gravitational potential energy and kinetic energy

5.2.1derive, using W = Fs , the formula ∆ E = mg ∆ h for gravitational potential energy changes in a uniform gravitational field
5.2.1amv 2 3 derive, using the equations of motion, the formula for kinetic energy E = 2
5.2.1bmv 2 4 recall and use E = 2
5.2.2recall and use the formula ∆ E = mg ∆ h for gravitational potential energy changes in a uniform gravitational field

6. Deformation of solids

1. Stress and strain

6.1.1understand that deformation is caused by tensile or compressive forces (forces and deformations will be assumed to be in one dimension only)
6.1.2understand and use the terms load, extension, compression and limit of proportionality
6.1.3recall and use Hooke’s law
6.1.4recall and use the formula for the spring constant k = F / x
6.1.5define and use the terms stress, strain and the Young modulus
6.1.6describe an experiment to determine the Young modulus of a metal in the form of a wire

2. Elastic and plastic behaviour

6.2.1understand and use the terms elastic deformation, plastic deformation and elastic limit
6.2.1a1 2 4 recall and use E = 2 Fx = 2 kx for a material deformed within its limit of proportionality
6.2.2understand that the area under the force–extension graph represents the work done
6.2.3determine the elastic potential energy of a material deformed within its limit of proportionality from the area under the force–extension graph

7. Waves

1. Progressive waves

7.1.1describe what is meant by wave motion as illustrated by vibration in ropes, springs and ripple tanks
7.1.2understand and use the terms displacement, amplitude, phase difference, period, frequency, wavelength and speed
7.1.3understand the use of the time-base and y -gain of a cathode-ray oscilloscope (CRO) to determine frequency and amplitude
7.1.4derive, using the definitions of speed, frequency and wavelength, the wave equation v = f λ
7.1.5recall and use v = f λ
7.1.6understand that energy is transferred by a progressive wave
7.1.7recall and use intensity = power/area and intensity ∝ ( amplitude ) for a progressive wave

2. Transverse and longitudinal waves

7.2.1compare transverse and longitudinal waves
7.2.2analyse and interpret graphical representations of transverse and longitudinal waves

3. Doppler effect for sound waves

7.3.1understand that when a source of sound waves moves relative to a stationary observer, the observed frequency is different from the source frequency (understanding of the Doppler effect for a stationary source and a moving observer is not required)
7.3.2use the expression f = f v / ( v ± v ) for the observed frequency when a source of sound waves moves relative to a stationary observer

4. Electromagnetic spectrum

7.4.1state that all electromagnetic waves are transverse waves that travel with the same speed c in free space
7.4.2recall the approximate range of wavelengths in free space of the principal regions of the electromagnetic spectrum from radio waves to γ -rays
7.4.3recall that wavelengths in the range 400–700 nm in free space are visible to the human eye

5. Polarisation

7.5.1understand that polarisation is a phenomenon associated with transverse waves
7.5.2recall and use Malus’s law ( I = I cos θ ) to calculate the intensity of a plane-polarised electromagnetic wave after transmission through a polarising filter or a series of polarising filters (calculation of the effect of a polarising filter on the intensity of an unpolarised wave is not required)

8. Superposition

1. Stationary waves

8.1.1explain and use the principle of superposition
8.1.2show an understanding of experiments that demonstrate stationary waves using microwaves, stretched strings and air columns (it will be assumed that end corrections are negligible; knowledge of the concept of end corrections is not required)
8.1.3explain the formation of a stationary wave using a graphical method, and identify nodes and antinodes
8.1.4understand how wavelength may be determined from the positions of nodes or antinodes of a stationary wave

2. Diffraction

8.2.1explain the meaning of the term diffraction
8.2.2show an understanding of experiments that demonstrate diffraction including the qualitative effect of the gap width relative to the wavelength of the wave; for example diffraction of water waves in a ripple tank

3. Interference

8.3.1understand the terms interference and coherence
8.3.2show an understanding of experiments that demonstrate two-source interference using water waves in a ripple tank, sound, light and microwaves
8.3.3understand the conditions required if two-source interference fringes are to be observed
8.3.4recall and use λ = ax / D for double-slit interference using light

4. The diffraction grating

8.4.1recall and use d sin θ = n λ
8.4.2describe the use of a diffraction grating to determine the wavelength of light (the structure and use of the spectrometer are not included)

9. Electricity

1. Electric current

9.1.1understand that an electric current is a flow of charge carriers
9.1.2understand that the charge on charge carriers is quantised
9.1.3recall and use Q = I t
9.1.4use, for a current-carrying conductor, the expression I = Anvq , where n is the number density of charge carriers

2. Potential difference and power

9.2.1define the potential difference across a component as the energy transferred per unit charge
9.2.2recall and use V = W / Q
9.2.3recall and use P = V I , P = I R and P = V / R

3. Resistance and resistivity

9.3.1define resistance
9.3.2recall and use V = I R
9.3.3sketch the I – V characteristics of a metallic conductor at constant temperature, a semiconductor diode and a filament lamp
9.3.4explain that the resistance of a filament lamp increases as current increases because its temperature increases
9.3.5state Ohm’s law
9.3.6recall and use R = ρ L / A
9.3.7understand that the resistance of a light-dependent resistor (LDR) decreases as the light intensity increases
9.3.8understand that the resistance of a thermistor decreases as the temperature increases (it will be assumed that thermistors have a negative temperature coefficient)

10. D.C. circuits

1. Practical circuits

10.1.1recall and use the circuit symbols shown in section 6 of this syllabus
10.1.2draw and interpret circuit diagrams containing the circuit symbols shown in section 6 of this syllabus
10.1.3define and use the electromotive force (e.m.f.) of a source as energy transferred per unit charge in driving charge around a complete circuit
10.1.4distinguish between e.m.f. and potential difference (p.d.) in terms of energy considerations
10.1.5understand the effects of the internal resistance of a source of e.m.f. on the terminal potential difference

2. Kirchhoff’s laws

10.2.1recall Kirchhoff’s first law and understand that it is a consequence of conservation of charge
10.2.2recall Kirchhoff’s second law and understand that it is a consequence of conservation of energy
10.2.3derive, using Kirchhoff’s laws, a formula for the combined resistance of two or more resistors in series
10.2.4use the formula for the combined resistance of two or more resistors in series
10.2.5derive, using Kirchhoff’s laws, a formula for the combined resistance of two or more resistors in parallel
10.2.6use the formula for the combined resistance of two or more resistors in parallel
10.2.7use Kirchhoff’s laws to solve simple circuit problems

3. Potential dividers

10.3.1understand the principle of a potential divider circuit
10.3.2recall and use the principle of the potentiometer as a means of comparing potential differences
10.3.3understand the use of a galvanometer in null methods
10.3.4explain the use of thermistors and light-dependent resistors in potential dividers to provide a potential difference that is dependent on temperature and light intensity

11. Particle physics

1. Atoms, nuclei and radiation

11.1.1infer from the results of the α -particle scattering experiment the existence and small size of the nucleus
11.1.2describe a simple model for the nuclear atom to include protons, neutrons and orbital electrons
11.1.3distinguish between nucleon number and proton number
11.1.4understand that isotopes are forms of the same element with different numbers of neutrons in their nuclei
11.1.5understand and use the notation X for the representation of nuclides
11.1.6
understand that nucleon number and charge are conserved in nuclear processes:
- +
11.1.7describe the composition, mass and charge of α -, β - and γ -radiations (both β (electrons) and β (positrons) are included)
11.1.8understand that an antiparticle has the same mass but opposite charge to the corresponding particle, and that a positron is the antiparticle of an electron
11.1.9state that (electron) antineutrinos are produced during β decay and (electron) neutrinos are produced during β decay
11.1.10understand that α -particles have discrete energies but that β -particles have a continuous range of energies because (anti)neutrinos are emitted in β -decay
11.1.11represent α - and β -decay by a radioactive decay equation of the form U " Th + α
11.1.12use the unified atomic mass unit (u) as a unit of mass

2. Fundamental particles

11.2.1understand that a quark is a fundamental particle and that there are six flavours (types) of quark: up, down, strange, charm, top and bottom
11.2.2recall and use the charge of each flavour of quark and understand that its respective antiquark has the opposite charge (no knowledge of any other properties of quarks is required)
11.2.3recall that protons and neutrons are not fundamental particles and describe protons and neutrons in terms of their quark composition
11.2.4
understand that a hadron may be either a baryon (consisting of three quarks) or a meson (consisting of one quark and one antiquark):
- +
11.2.5describe the changes to quark composition that take place during β and β decay
11.2.6recall that electrons and neutrinos are fundamental particles called leptons

12. Motion in a circle

1. Kinematics of uniform circular motion

12.1.1define the radian and express angular displacement in radians
12.1.2understand and use the concept of angular speed
12.1.3recall and use ω = 2 π / T and v = r ω

2. Centripetal acceleration

12.2.1understand that a force of constant magnitude that is always perpendicular to the direction of motion causes centripetal acceleration
12.2.2understand that centripetal acceleration causes circular motion with a constant angular speed
12.2.3recall and use a = r ω and a = v / r
12.2.4recall and use F = mr ω and F = mv / r

13. Gravitational fields

1. Gravitational field

13.1.1understand that a gravitational field is an example of a field of force and define gravitational field as force per unit mass
13.1.2represent a gravitational field by means of field lines

2. Gravitational force between point masses

13.2.1understand that, for a point outside a uniform sphere, the mass of the sphere may be considered to be a point mass at its centre
13.2.1a2 3 analyse circular orbits in gravitational fields by relating the gravitational force to the centripetal acceleration it causes 4 understand that a satellite in a geostationary orbit remains at the same point above the Earth’s surface, with an orbital period of 24 hours, orbiting from west to east, directly above the Equator
13.2.2recall and use Newton’s law of gravitation F = Gm m / r for the force between two point masses

3. Gravitational field of a point mass

13.3.1derive, from Newton’s law of gravitation and the definition of gravitational field, the equation g = GM / r for the gravitational field strength due to a point mass
13.3.2recall and use g = GM / r
13.3.3understand why g is approximately constant for small changes in height near the Earth’s surface

4. Gravitational potential

13.4.1define gravitational potential at a point as the work done per unit mass in bringing a small test mass from infinity to the point
13.4.2use ϕ = – GM / r for the gravitational potential in the field due to a point mass
13.4.3understand how the concept of gravitational potential leads to the gravitational potential energy of two point masses and use E = – GMm / r

14. Temperature

1. Thermal equilibrium

14.1.1understand that (thermal) energy is transferred from a region of higher temperature to a region of lower temperature
14.1.2understand that regions of equal temperature are in thermal equilibrium

2. Temperature scales

14.2.1understand that a physical property that varies with temperature may be used for the measurement of temperature and state examples of such properties, including the density of a liquid, volume of a gas at constant pressure, resistance of a metal, e.m.f. of a thermocouple
14.2.2understand that the scale of thermodynamic temperature does not depend on the property of any particular substance
14.2.3convert temperatures between kelvin and degrees Celsius and recall that T / K = θ / °C + 273.15
14.2.4understand that the lowest possible temperature is zero kelvin on the thermodynamic temperature scale and that this is known as absolute zero

3. Specific heat capacity and specific latent heat

14.3.1define and use specific heat capacity
14.3.2define and use specific latent heat and distinguish between specific latent heat of fusion and specific latent heat of vaporisation

15. Ideal gases

1. The mole

15.1.1understand that amount of substance is an SI base quantity with the base unit mol
15.1.2use molar quantities where one mole of any substance is the amount containing a number of particles of that substance equal to the Avogadro constant N

2. Equation of state

15.2.1understand that a gas obeying pV ∝ T , where T is the thermodynamic temperature, is known as an ideal gas
15.2.2recall and use the equation of state for an ideal gas expressed as pV = nRT , where n = amount of substance (number of moles) and as pV = NkT , where N = number of molecules
15.2.3recall that the Boltzmann constant k is given by k = R / N

3. Kinetic theory of gases

15.3.1state the basic assumptions of the kinetic theory of gases
15.3.1aNm 2 2 relationship pV = 3 < c >, where < c > is the mean-square speed (a simple model considering
15.3.1b< 2 2 one-dimensional collisions and then extending to three dimensions using 3 c > = < c > is sufficient) 3 understand that the root-mean-square speed c is given by < c >
15.3.1cNm 2 4 compare pV = 3 < c > with pV = NkT to deduce that the average translational kinetic energy of a molecule is 2 kT , and recall and use this expression
15.3.2explain how molecular movement causes the pressure exerted by a gas and derive and use the

16. Thermodynamics

1. Internal energy

16.1.1understand that internal energy is determined by the state of the system and that it can be expressed as the sum of a random distribution of kinetic and potential energies associated with the molecules of a system
16.1.2relate a rise in temperature of an object to an increase in its internal energy

2. The first law of thermodynamics

16.2.1recall and use W = p ∆ V for the work done when the volume of a gas changes at constant pressure and understand the difference between the work done by the gas and the work done on the gas
16.2.2recall and use the first law of thermodynamics ∆ U = q + W expressed in terms of the increase in internal energy, the heating of the system (energy transferred to the system by heating) and the work done on the system

17. Oscillations

1. Simple harmonic oscillations

17.1.1understand and use the terms displacement, amplitude, period, frequency, angular frequency and phase difference in the context of oscillations, and express the period in terms of both frequency and angular frequency
17.1.2understand that simple harmonic motion occurs when acceleration is proportional to displacement from a fixed point and in the opposite direction
17.1.3use a = – ω x and recall and use, as a solution to this equation, x = x sin ω t
17.1.4use the equations v = v cos ω t and v = ± ω ( x − x )
17.1.5analyse and interpret graphical representations of the variations of displacement, velocity and acceleration for simple harmonic motion

2. Energy in simple harmonic motion

17.2.1describe the interchange between kinetic and potential energy during simple harmonic motion
17.2.1am 2 2
17.2.2recall and use E = 2 ω x for the total energy of a system undergoing simple harmonic motion

3. Damped and forced oscillations, resonance

17.3.1understand that a resistive force acting on an oscillating system causes damping
17.3.2understand and use the terms light, critical and heavy damping and sketch displacement–time graphs illustrating these types of damping
17.3.3understand that resonance involves a maximum amplitude of oscillations and that this occurs when an oscillating system is forced to oscillate at its natural frequency

18. Electric fields

1. Electric fields and field lines

18.1.1understand that an electric field is an example of a field of force and define electric field as force per unit positive charge
18.1.2recall and use F = qE for the force on a charge in an electric field
18.1.3represent an electric field by means of field lines

2. Uniform electric fields

18.2.1recall and use E = ∆ V / ∆ d to calculate the field strength of the uniform field between charged parallel plates
18.2.2describe the effect of a uniform electric field on the motion of charged particles

3. Electric force between point charges

18.3.1understand that, for a point outside a spherical conductor, the charge on the sphere may be considered to be a point charge at its centre
18.3.1a2 0
18.3.2recall and use Coulomb’s law F = Q Q / (4 π ε r ) for the force between two point charges in free space

4. Electric field of a point charge

18.4.1recall and use E = Q / (4 π ε r ) for the electric field strength due to a point charge in free space

5. Electric potential

18.5.1define electric potential at a point as the work done per unit positive charge in bringing a small test charge from infinity to the point
18.5.2recall and use the fact that the electric field at a point is equal to the negative of potential gradient at that point
18.5.3use V = Q / (4 π ε r ) for the electric potential in the field due to a point charge
18.5.4understand how the concept of electric potential leads to the electric potential energy of two point charges and use E = Qq / (4 π ε r )

19. Capacitance

1. Capacitors and capacitance

19.1.1define capacitance, as applied to both isolated spherical conductors and to parallel plate capacitors
19.1.2recall and use C = Q / V
19.1.3derive, using C = Q / V , formulae for the combined capacitance of capacitors in series and in parallel
19.1.4use the capacitance formulae for capacitors in series and in parallel

2. Energy stored in a capacitor

19.2.1determine the electric potential energy stored in a capacitor from the area under the potential–charge graph
19.2.1aQV 1 CV 2
19.2.2recall and use W = 2 = 2

3. Discharging a capacitor

19.3.1analyse graphs of the variation with time of potential difference, charge and current for a capacitor discharging through a resistor
19.3.2recall and use τ = RC for the time constant for a capacitor discharging through a resistor
19.3.3use equations of the form x = x e where x could represent current, charge or potential difference for a capacitor discharging through a resistor

20. Magnetic fields

1. Concept of a magnetic field

20.1.1understand that a magnetic field is an example of a field of force produced either by moving charges or by permanent magnets
20.1.2represent a magnetic field by field lines

2. Force on a current-carrying conductor

20.2.1understand that a force might act on a current-carrying conductor placed in a magnetic field
20.2.2recall and use the equation F = B I L sin θ , with directions as interpreted by Fleming’s left-hand rule
20.2.3define magnetic flux density as the force acting per unit current per unit length on a wire placed at right- angles to the magnetic field

3. Force on a moving charge

20.3.1determine the direction of the force on a charge moving in a magnetic field
20.3.2recall and use F = BQv sin θ
20.3.3understand the origin of the Hall voltage and derive and use the expression V = B I / ( ntq ), where t = thickness
20.3.4understand the use of a Hall probe to measure magnetic flux density
20.3.5describe the motion of a charged particle moving in a uniform magnetic field perpendicular to the direction of motion of the particle
20.3.6explain how electric and magnetic fields can be used in velocity selection

4. Magnetic fields due to currents

20.4.1sketch magnetic field patterns due to the currents in a long straight wire, a flat circular coil and a long solenoid
20.4.2understand that the magnetic field due to the current in a solenoid is increased by a ferrous core
20.4.3explain the origin of the forces between current-carrying conductors and determine the direction of the forces

5. Electromagnetic induction

20.5.1define magnetic flux as the product of the magnetic flux density and the cross-sectional area perpendicular to the direction of the magnetic flux density
20.5.2recall and use Φ = BA
20.5.3understand and use the concept of magnetic flux linkage
20.5.4
understand and explain experiments that demonstrate:
- that a changing magnetic flux can induce an e.m.f. in a circuit
- that the induced e.m.f. is in such a direction as to oppose the change producing it
- the factors affecting the magnitude of the induced e.m.f.
20.5.5recall and use Faraday’s and Lenz’s laws of electromagnetic induction

21. Alternating currents

1. Characteristics of alternating currents

21.1.1understand and use the terms period, frequency and peak value as applied to an alternating current or voltage
21.1.2use equations of the form x = x sin ω t representing a sinusoidally alternating current or voltage
21.1.3recall and use the fact that the mean power in a resistive load is half the maximum power for a sinusoidal alternating current
21.1.4distinguish between root-mean-square (r.m.s.) and peak values and recall and use I = I / 2 and V = V / 2 for a sinusoidal alternating current

2. Rectification and smoothing

21.2.1distinguish graphically between half-wave and full-wave rectification
21.2.2explain the use of a single diode for the half-wave rectification of an alternating current
21.2.3explain the use of four diodes (bridge rectifier) for the full-wave rectification of an alternating current
21.2.4analyse the effect of a single capacitor in smoothing, including the effect of the values of capacitance and the load resistance

22. Quantum physics

1. Energy and momentum of a photon

22.1.1understand that electromagnetic radiation has a particulate nature
22.1.2understand that a photon is a quantum of electromagnetic energy
22.1.3recall and use E = hf
22.1.4use the electronvolt (eV) as a unit of energy
22.1.5understand that a photon has momentum and that the momentum is given by p = E / c

2. Photoelectric effect

22.2.1understand that photoelectrons may be emitted from a metal surface when it is illuminated by electromagnetic radiation
22.2.1amv 2 4 recall and use hf = Φ + 2 max 5 explain why the maximum kinetic energy of photoelectrons is independent of intensity, whereas the photoelectric current is proportional to intensity
22.2.2understand and use the terms threshold frequency and threshold wavelength
22.2.3explain photoelectric emission in terms of photon energy and work function energy

3. Wave-particle duality

22.3.1understand that the photoelectric effect provides evidence for a particulate nature of electromagnetic radiation while phenomena such as interference and diffraction provide evidence for a wave nature
22.3.2describe and interpret qualitatively the evidence provided by electron diffraction for the wave nature of particles
22.3.3understand the de Broglie wavelength as the wavelength associated with a moving particle
22.3.4recall and use λ = h / p

4. Energy levels in atoms and line spectra

22.4.1understand that there are discrete electron energy levels in isolated atoms (e.g. atomic hydrogen)
22.4.1a2
22.4.2understand the appearance and formation of emission and absorption line spectra
22.4.3recall and use hf = E – E

23. Nuclear physics

1. Mass defect and nuclear binding energy

23.1.1understand the equivalence between energy and mass as represented by E = mc and recall and use this equation
23.1.2represent simple nuclear reactions by nuclear equations of the form N + He " O + H
23.1.3define and use the terms mass defect and binding energy
23.1.4sketch the variation of binding energy per nucleon with nucleon number
23.1.5explain what is meant by nuclear fusion and nuclear fission
23.1.6explain the relevance of binding energy per nucleon to nuclear reactions, including nuclear fusion and nuclear fission
23.1.7calculate the energy released in nuclear reactions using E = c ∆ m

2. Radioactive decay

23.2.1understand that fluctuations in count rate provide evidence for the random nature of radioactive decay
23.2.2understand that radioactive decay is both spontaneous and random
23.2.3define activity and decay constant, and recall and use A = λ N
23.2.4define half-life
23.2.5
use λ = 0.693 / t 1:
- λ t
23.2.6understand the exponential nature of radioactive decay, and sketch and use the relationship x = x e , where x could represent activity, number of undecayed nuclei or received count rate

24. Medical physics

1. Production and use of ultrasound

24.1.1understand that a piezo-electric crystal changes shape when a p.d. is applied across it and that the crystal generates an e.m.f. when its shape changes
24.1.2understand how ultrasound waves are generated and detected by a piezoelectric transducer
24.1.3understand how the reflection of pulses of ultrasound at boundaries between tissues can be used to obtain diagnostic information about internal structures
24.1.4define the specific acoustic impedance of a medium as Z = ρ c , where c is the speed of sound in the medium
24.1.5
use I / I = ( Z – Z ) / ( Z + Z ) for the intensity reflection coefficient of a boundary between two media:
- μ x
24.1.6recall and use I = I e for the attenuation of ultrasound in matter

2. Production and use of X-rays

24.2.1explain that X-rays are produced by electron bombardment of a metal target and calculate the minimum wavelength of X-rays produced from the accelerating p.d.
24.2.2
understand the use of X-rays in imaging internal body structures, including an understanding of the term contrast in X-ray imaging:
- μ x
24.2.3recall and use I = I e for the attenuation of X-rays in matter
24.2.4understand that computed tomography (CT) scanning produces a 3D image of an internal structure by first combining multiple X-ray images taken in the same section from different angles to obtain a 2D image of the section, then repeating this process along an axis and combining 2D images of multiple sections

3. PET scanning

24.3.1understand that a tracer is a substance containing radioactive nuclei that can be introduced into the body and is then absorbed by the tissue being studied
24.3.2recall that a tracer that decays by β decay is used in positron emission tomography (PET scanning)
24.3.3understand that annihilation occurs when a particle interacts with its antiparticle and that mass–energy and momentum are conserved in the process
24.3.4explain that, in PET scanning, positrons emitted by the decay of the tracer annihilate when they interact with electrons in the tissue, producing a pair of gamma-ray photons travelling in opposite directions
24.3.5calculate the energy of the gamma-ray photons emitted during the annihilation of an electron-positron pair
24.3.6understand that the gamma-ray photons from an annihilation event travel outside the body and can be detected, and an image of the tracer concentration in the tissue can be created by processing the arrival times of the gamma-ray photons

25. Astronomy and cosmology

1. Standard candles

25.1.1understand the term luminosity as the total power of radiation emitted by a star
25.1.2recall and use the inverse square law for radiant flux intensity F in terms of the luminosity L of the source
25.1.3understand that an object of known luminosity is called a standard candle
25.1.4understand the use of standard candles to determine distances to galaxies

2. Stellar radii

25.2.1recall and use Wien’s displacement law λ ∝ 1 / T to estimate the peak surface temperature of a star max
25.2.24 2 use the Stefan–Boltzmann law L = 4 π σ r T
25.2.3use Wien’s displacement law and the Stefan–Boltzmann law to estimate the radius of a star

3. Hubble’s law and the Big Bang theory

25.3.1understand that the lines in the emission and absorption spectra from distant objects show an increase in wavelength from their known values
25.3.2use ∆ λ / λ . ∆ f / f . v / c for the redshift of electromagnetic radiation from a source moving relative to an observer
25.3.3explain why redshift leads to the idea that the Universe is expanding
25.3.4recall and use Hubble’s law v . H d and explain how this leads to the Big Bang theory (candidates will only be required to use SI units)