International Baccalaureate


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Option A - Relativity  


The Core and Additional Higher Syllabus has topics in each of the four options.  You take one of the options.  If you are lucky enough to be in a centre with four physics groups, you may have the opportunity to choose the option you do.  In most schools and colleges,  the tutor will choose it for you.

Note:  The syllabus statements about the following have been omitted for space reasons:

  • Nature of Science;

  • International mindedness;

  • Theory of knowledge;

  • Utilisation;

  • Aims.

You can find these statements in the syllabus.

Guidance shown like this is extra guidance from me, not the syllabus.

In the exam, you are expected to understand:

Option A - Relativity

A.1  The Beginnings of Relativity (Core)




Equations Link

Reference frames;


Galilean relativity and Newton’s postulates concerning time and space;

Maxwell and the constancy of the speed of light;

Forces on a charge or current.

Using the Galilean transformation equations;

Determining whether a force on a charge or current is electric or magnetic in a given frame of reference;

Determining the nature of the fields observed by different observers.

Maxwell’s equations do not need to be described;


Qualitative treatment of electric and magnetic fields as measured by
observers in relative motion. Examples will include a charge moving in a
magnetic field or two charged particles moving with parallel velocities;

Students will be asked to analyse these motions from the point of view of
observers at rest with respect to the particles and observers at rest with
respect to the magnetic field.

Turning Points 5

(Basic relativity)


Turning Points 6

(Electric and magnetic fields)


Physics 6 Tutorial 1


A.2  The Lorentz Transformation (Core)

The two postulates of special relativity;


Clock synchronization;


The Lorentz transformations;


Velocity addition;


Invariant quantities (spacetime interval, proper time, proper length and rest mass);


Time dilation;


Length contraction;


The muon decay experiment.

Using the Lorentz transformations to describe how different measurements of space and time by two observers can be converted into the measurements observed in either frame of reference;

Using the Lorentz transformation equations to determine the position and time coordinates of various events;


Using the Lorentz transformation equations to show that if two events are simultaneous for one observer but happen at different points in space, then the events are not simultaneous for an observer in a different reference frame;


Solving problems involving velocity addition;


Deriving the time dilation and length contraction equations using the Lorentz equations;


Solving problems involving time dilation and length contraction;


Solving problems involving the muon decay experiment

Problems will be limited to one dimension;


Derivation of the Lorentz transformation equations will not be examined;


Muon decay experiments can be used as evidence for both time dilation and
length contraction

Turning Points 6

(Special Relativity)


A.3  Space-time Diagrams (Core)

Spacetime diagrams;




The twin paradox.

Representing events on a spacetime diagram as points;


Representing the positions of a moving particle on a spacetime diagram by a curve (the worldline);


Representing more than one inertial reference frame on the same spacetime diagram;


Determining the angle between a worldline for specific speed and the time axis on a spacetime diagram;


Solving problems on simultaneity and kinematics using spacetime diagrams;


Representing time dilation and length contraction on spacetime diagrams;


Describing the twin paradox;


Resolving of the twin paradox through spacetime diagrams.

Examination questions will refer to spacetime diagrams; these are also known as Minkowski diagrams;


Quantitative questions involving spacetime diagrams will be limited to
constant velocity;


Spacetime diagrams can have t or ct on the vertical axis;


Examination questions may use units in which c = 1.

Physics 6 Tutorial 1

(Spacetime Diagrams)


Physics 6 Tutorial 18

A.4  Relativistic Mechanics  (Additional Higher)




Equations Link

Total energy and rest energy;


Relativistic momentum;

Particle acceleration;

Electric charge as an invariant quantity;


MeV c–2 as the unit of mass and MeV c–1 as the unit of momentum.

Describing the laws of conservation of momentum and conservation of
energy within special relativity

Determining the potential difference necessary to accelerate a particle to a given speed or energy;

Solving problems involving relativistic energy and momentum conservation in collisions and particle decays.

Applications will involve relativistic decays such as calculating the
wavelengths of photons in the decay of a moving pion [ π0 -> 2γ ];


The symbol m0 refers to the invariant rest mass of a particle;

The concept of a relativistic mass that varies with speed will not be used;


Problems will be limited to one dimension

Particles 4



Physics 6 Tutorial 19

(Relativistic Mechanics)

A.5  General Relativity (Additional Higher)

The equivalence principle;


The bending of light;

Gravitational redshift and the Pound–Rebka–Snider experiment;

Schwarzschild black holes;

Event horizons;

Time dilation near a black hole

Applications of general relativity to the universe as a whole.

Using the equivalence principle to deduce and explain light bending near massive objects;


Using the equivalence principle to deduce and explain gravitational time dilation;


Calculating gravitational frequency shifts;


Describing an experiment in which gravitational redshift is observed
and measured;


Calculating the Schwarzschild radius of a black hole;


Applying the formula for gravitational time dilation near the event horizon of a black hole.

Students should recognize the equivalence principle in terms of accelerating reference frames and freely falling frames.

Physics 6 Tutorial 1



Astrophysics 6

(Schwarzchild Radius)


Physics 6 Tutorial 20 - Pound Rebka Experiment


Physics 6 Tutorial 20

Gravitational Time Dilation


  I am currently working on the final tutorial of Option A - Relativity.  I will have several more tutorials to write to cover the syllabus content for Options B, C, and D.  Please be patient.  They will come.