What the board asks

We went through the ISC board papers, question by question, and matched each question to a topic. Here is what was asked, how often, and what was never asked.

Physics: 427 topics in the 2027 syllabus, across 9 units. The board has asked 269 of them at least once. 158 were never asked in the papers we checked.

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P3 Magnetic Effects of Current and Magnetism

All the topics in Physics: Magnetic Effects of Current and Magnetism

Asked topics first, the most asked at the top. Tap a topic to see what to write, the result, the years, and the real board questions.

97 topics shown

#	Topic	Type	Marks	Times asked	Last asked	Status
1	Derive B at the centre of a circular loopApply the Biot-Savart law to an element of the loop with the centre as field point (theta = 90 deg), sum over the circumference to get B, extend to N turns, and show the direction for clockwise and anticlockwise current.	Derivation	3	9 papers	2026	Asked
2	Magnetic force on a moving charge and Lorentz forceWrite the force on a moving charge in magnitude and vector form with the meaning of each symbol, state when it is zero and when it is maximum, say which pairs of vectors are always perpendicular, and write the total Lorentz force in E and B together.	Statement	2	8 papers	2026	Asked
3	Derive force between parallel wires; define ampereDraw two long parallel wires, write the field of the first at the second, use F = I l B to get the force per unit length, show with the left-hand rule that like currents attract and unlike repel, and use the result to define one ampere.	Derivation	3	8 papers	2025 improvement	Asked
4	Curie's law, Curie-Weiss law and Curie temperatureState Curie's law for a paramagnetic substance in both forms and explain it by thermal agitation, state the Curie-Weiss law for ferromagnetics, define Curie temperature with the values for iron and nickel, and say what happens to a ferromagnet above it.	Statement	2	7 papers	2026	Asked
5	Charge in uniform B: paths, radius, period, frequencyState the path for motion along the field, perpendicular to it and at an angle; for the perpendicular case equate the magnetic force to the centripetal force to get the radius, then the period, frequency and angular frequency, and show that radius depends on momentum while period and frequency do not depend on speed.	Derivation	3	6 papers	Specimen 2026	Asked
6	Ampere's law: derive B near a long straight wireChoose a circular path of radius r centred on the wire, argue that B is tangential and constant on it, evaluate the line integral to get B, state the direction, and say why the same argument fails for a wire of finite length.	Derivation	3	6 papers	Specimen 2026	Asked
7	Numericals: B at the centre of a circular coilCompute B at the centre of a coil of N turns, combine two concentric coils with their directions, and work out how B changes when the current, turns or radius are changed or when the same wire is rewound into more turns.	Numericals	2	6 papers	2025	Asked
8	Compare dia, para and ferromagnetic substances (table)Draw up a table contrasting the three classes on effect of a magnet, direction and strength of magnetisation, flux density inside, susceptibility, relative permeability, behaviour in uniform and non-uniform fields, temperature dependence and examples.	Comparison	3	6 papers	2025 improvement	Asked
9	Solenoid: field lines, B inside and at endsSay what a solenoid is, draw its field lines (uniform and parallel inside, like a bar magnet outside), write B inside and at one end, and reason how B changes with current, turns per unit length, an iron core, length and cross-section.	Diagram	2	5 papers	Specimen 2027	Asked
10	State Biot-Savart law with vector formState the law in words for a current element, draw the element with r and theta, write it in scalar and vector form explaining every symbol, give the value, unit and dimensions of mu0 (and of mu0/4pi and 1/sqrt(mu0 eps0)), and note where the field of an element is zero and maximum.	Statement	2	5 papers	2026	Asked
11	Numericals: force between parallel wiresCalculate the force (or force per unit length) on a given length of one wire due to a parallel wire, state attraction or repulsion, and find the net force on a third wire placed between or beside two others.	Numericals	2	5 papers	Specimen 2026	Asked
12	Galvanometer design reasons: radial field, core, frame, suspensionGive one or two line reasons: what a radial field is, how it is produced and why it is useful, why the pole pieces are cylindrical, why a soft-iron core, an aluminium frame and a phosphor-bronze strip are used, and why the earth's field does not matter.	Give reason	2	5 papers	Specimen 2026	Asked
13	Direction of B: right-hand rules and field linesState the right-hand thumb rule (and palm rule 1 or Maxwell's screw rule), draw the concentric field lines round a straight current with arrows and the dot and cross notation, and apply the rule to give the field direction at a named point, at the centre of a loop, or for a moving charge.	Diagram	2	4 papers	Specimen 2027	Asked
14	Numericals: B of a long straight wireCompute B at a given distance from a long straight wire and give its direction in compass or up-down terms using the right-hand thumb rule; for an electron beam first get the current or the number of electrons per second.	Numericals	2	4 papers	Specimen 2027	Asked
15	Choice of materials: permanent magnets, electromagnets, transformer coresState the properties needed in a material for a permanent magnet, an electromagnet core and a transformer core or telephone diaphragm, justify each from retentivity, coercivity, permeability, hysteresis loss and resistivity, and name the materials used.	Give reason	3	4 papers	Specimen 2027	Asked
16	Convert galvanometer to voltmeter: derive series resistanceDraw the galvanometer with a high resistance in series, apply Ohm's law at full-scale deflection to derive the resistance needed for a given range, and give the resistance of the voltmeter.	Derivation	2	4 papers	2025 improvement	Asked
17	Numericals: radius, period, frequency of circular pathFrom the speed, charge, mass and field compute the radius, period or frequency of the circle (or work back to the speed or the field), say how the radius changes when the field changes, and state that the frequency does not depend on speed.	Numericals	3	3 papers	Specimen 2026	Asked
18	Convert galvanometer to ammeter: derive the shuntDraw the galvanometer with a low resistance in parallel, equate the potential differences across coil and shunt to derive the shunt for a given range and the fraction of current through the coil, and give the resistance of the ammeter.	Derivation	3	3 papers	2025 improvement	Asked
19	Numericals: shunt, range and resistance of an ammeterFind the full-scale current from the scale data, then the shunt for a required range, the new maximum current for a given shunt, the fraction of current through the coil, and the resistance of the finished ammeter (including extending an existing ammeter).	Numericals	2	3 papers	2023	Asked
20	Bar magnet: poles, pole strength, magnetic length, dipole moment, propertiesDefine a bar magnet, its pole strength, magnetic length and dipole moment with direction and SI units, label a diagram showing the axis, equator, geometric length and magnetic length, and list the five properties of a bar magnet.	Statement	2	3 papers	2022 Sem-I	Asked
21	Reasoning: using ammeters and voltmeters in circuitsGive reasons for the low resistance and series connection of an ammeter, the high resistance and parallel connection of a voltmeter, what happens if they are swapped, whether they read the true values, how the range of each can be raised or lowered, and which of two shunts is larger.	Give reason	2	2 papers	Specimen 2027	Asked
22	Define dia, para and ferromagnetic substances with examplesDefine the three classes by how strongly and in which direction they are magnetised in an applied field and how they respond to a strong magnet, give several examples of each, and note that every substance is basically diamagnetic.	Statement	2	2 papers	Specimen 2027	Asked
23	State and explain Ampere's circuital lawState the law in words and as a line integral, explain what the enclosed current means, verify it for a circular path round a long straight wire, note that it holds for steady currents and any closed path, and say for which current shapes it is useful compared with Biot-Savart.	Statement	2	2 papers	2026	Asked
24	Numericals: sensitivity changes and figure of meritCompare the current and voltage sensitivities of two meters, find the effect on voltage sensitivity when turns and resistance are changed, get the galvanometer resistance from the two sensitivities, and compute the figure of merit from a circuit.	Numericals	3	2 papers	Specimen 2026	Asked
25	Graphs of susceptibility versus temperature for the three classesSketch chi_m against kelvin temperature for a diamagnetic substance (horizontal line below the axis), a paramagnetic substance (falling 1/T curve) and a ferromagnetic substance (falling through Tc, with the ferromagnetic and paramagnetic regions marked), labelling axes and writing the law beside each.	Diagram	2	2 papers	Specimen 2026	Asked
26	Numericals: resultant B of two long wiresAdd or subtract the fields of two parallel wires at points between and outside them, add at right angles for crossed wires or wires seen end-on, and locate the neutral point where the resultant is zero for currents in the same or opposite directions.	Numericals	3	2 papers	2025	Asked
27	Reasoning: attraction and repulsion between currentsExplain with field and left-hand rule why like parallel currents attract and unlike repel, and apply it to a spring carrying current, a wire that moves towards another, wires that should repel but attract, and a straight wire along the axis of a loop (no force).	Give reason	1	2 papers	2025	Asked
28	Numericals: series resistance and range of a voltmeterFind the series resistance for a required voltage range, the range obtained with a given resistance, the extra resistance to extend an existing voltmeter, and the resistance of the finished voltmeter.	Numericals	2	2 papers	2025	Asked
29	*Moving coil galvanometer: diagram, principle, theory I = kphi*Draw a labelled diagram (coil, pole pieces, soft-iron core, suspension strip, mirror or pointer), state the principle, describe the construction and the radial field, equate deflecting torque NIAB to restoring torque cphi to show current is proportional to deflection, and explain how the deflection is read.	Device	5	2 papers	2024	Asked
30	Numericals: charge moving parallel to a long wireFind the field of the long straight wire at the position of the charge, then the force on the electron or proton moving parallel to the wire, and state whether it is pushed towards or away from the wire.	Numericals	2	2 papers	2023	Asked
31	Numericals: arcs, semicircles and composite wiresFind B at the common centre of arcs and semicircles by taking the arc fraction of the full-loop field, add or subtract the parts with their directions, treat straight pieces pointing at the centre as zero, and add the long-wire term when a straight part passes at a distance.	Numericals	3	2 papers	2022 Sem-I	Asked
32	Numericals: mu, mu_r, chi_m, B, H, M and fluxUse B = Phi/A, mu = B/H, mu_r = mu/mu0, chi_m = mu_r - 1, M = chi_m H and m = M V to find permeability, relative permeability, susceptibility, magnetisation, flux or magnetic moment of a specimen from the given data.	Numericals	2	2 papers	2017	Asked
33	Numericals: force on a moving chargeCalculate the magnitude and direction of the magnetic force (and the acceleration) on a charge from q, v, B and the angle, or from i-j-k components using the cross product, including finding the speed from the kinetic energy first and using F.v = 0 to find a missing component.	Numericals	2	2 papers	2006	Asked
34	Find the direction a moving charge is deflectedGiven the directions of velocity and field (compass directions, axes or a diagram of tracks), use Fleming's left-hand rule or the cross product to state the direction of force, the sense of circulation, the sign of the charge or the direction of the unknown field, remembering to reverse for an electron.	Give reason	1	1 paper	Specimen 2027	Asked
35	Crossed E and B fields: velocity selectorDraw a charge entering mutually perpendicular E and B, mark the opposite electric and magnetic forces, set them equal to get the speed that passes undeflected, and say which way faster or slower particles bend and what the device is used for.	Derivation	3	1 paper	Specimen 2027	Asked
36	Derive B on the axis of a circular loopDraw the loop with a current element, the point on the axis and the resolved components of dB, argue that the perpendicular components cancel, integrate the axial components to get B at distance x, extend to N turns, give the direction, and show the limits at the centre and far away.	Derivation	5	1 paper	Specimen 2027	Asked
37	Compare soft iron and steel from their hysteresis loopsSketch the two loops on the same axes (soft iron tall and narrow, steel shorter and wide) and compare soft iron and steel on retentivity, coercivity, hysteresis loss and permeability.	Comparison	2	1 paper	Specimen 2027	Asked
38	Numericals: B on the axis of a coilUse the axial formula to find B at a point on the axis (with direction), the distance at which B falls to a given fraction of its central value, or the field midway between two coaxial coils.	Numericals	2	1 paper	Specimen 2026	Asked
39	Magnetic field: definition, tesla, gauss, dimensionsDefine magnetic field as a region and through B = F/(q v sin theta), state the direction of B, define one tesla in words, express the tesla in base SI units, and write its other units, the gauss relation and the dimensions of B.	Statement	3	1 paper	2022 Sem-I	Asked
40	Derive mu_r = 1 + chi_m; oersted to A/mStarting from B = mu0 (H + M) with M = chi_m H and B = mu H, obtain the relation between permeability and susceptibility and hence between relative permeability and susceptibility, and convert 1 oersted into A/m using 1 gauss/mu0.	Derivation	3	1 paper	2020	Asked
41	Numericals: torque on a coil, tau = NIAB sin(theta)Compute the torque on a rectangular, circular, triangular or irregular coil, first converting the given angle to the angle between the normal and the field, and answer follow-ups on zero torque, net force, changing area or turns, and whether shape matters for the same area.	Numericals	2	1 paper	2019	Asked
42	Numericals: wire held up by magnetic forceEquate the magnetic force per unit length from a fixed wire to the weight per unit length of the free wire to find the separation or current, and decide the current directions needed when the free wire is above or below.	Numericals	3	1 paper	2018	Asked
43	Numericals: B inside a solenoidWork out the turns per metre (including several layers), then B at the centre and at the ends, or work back to the number of turns or the current, and suggest a design that gives a required field.	Numericals	2	1 paper	2014	Asked
44	Derive torque on a bar magnet; define magnetic momentUsing the picture of the magnet as N aligned atomic current loops, each feeling torque I A B sin(theta), obtain the torque on a bar magnet in a uniform field in scalar and vector form, discuss the maximum and zero cases, and from the maximum case define magnetic moment and deduce its SI unit, with a diagram.	Derivation	3	1 paper	2010	Asked
45	Numericals: torque on a magnet, tau = mB sin(theta)Use tau = m B sin(theta) to find the torque, the magnetic moment, the field or the ratio of two fields for a magnet, needle, coil or solenoid held at a given angle to a uniform field, stating the sense of the torque.	Numericals	2	1 paper	2010	Asked
46	State axial and equatorial fields of a bar magnetWrite the field of a bar magnet at an end-on (axial) point and at a broad-side-on (equatorial) point, both for a magnet of length 2l and for a short magnet, explain every symbol, give the direction in each case with a small diagram, and note the 2:1 ratio and 1/r^3 dependence.	Statement	2	1 paper	about 2008	Asked
47	Numericals: B at centre of a revolving charge's orbitTurn a charge moving round a circle into an equivalent current using its frequency or speed, then find the field at the centre of the orbit.	Numericals	2	1 paper	2006	Asked
48	Current and voltage sensitivity; figure of meritDefine current sensitivity and voltage sensitivity with their formulas and units, define figure of merit, list the factors that raise sensitivity and how each is achieved in practice, and explain why more turns need not raise voltage sensitivity.	Statement	2	1 paper	2006	Asked
49	Numericals: force on a straight current-carrying conductorCompute the magnitude and direction of the force (or force per unit length) on a wire from I, l, B and the angle, including a wire inside a solenoid, a wire crossing a limited field region, the force on one drifting electron and the resulting acceleration of a rod on rails.	Numericals	2	1 paper	2004	Asked
50	Hysteresis loop: sketch; saturation, retentivity, coercivity, hysteresisDraw a labelled hysteresis loop for one full cycle of magnetisation, describe the path from the unmagnetised state to saturation and round the loop, and define magnetic saturation, residual magnetism (retentivity), coercive force (coercivity) and hysteresis, marking retentivity and coercivity on the axes.	Diagram	5	1 paper	2002	Asked
51	Oersted's experiment: observations and conclusionDescribe the wire-over-compass-needle experiment with a small sketch (no current, current, reversed current), state what it proves, and use the right-hand thumb rule to predict which way a needle turns under a given current or electron beam.	Statement	2	never		Never asked
52	Field lines are closed loops; no magnetic monopolesExplain in two or three lines why magnetic field lines form closed loops, why the poles of a magnet cannot be separated, what happens when a bar magnet is cut across or along its length, and why a toroid has no poles.	Give reason	1	never		Never asked
53	Give reasons: magnetic force does no workAnswer short why-questions: why speed and kinetic energy stay constant but momentum changes, why a charge at rest feels no magnetic force, why no deflection does not prove B = 0 and deflection does not prove B exists, how to tell a magnetic field from an electric field by the path, and why the force does not depend on mass.	Give reason	2	never		Never asked
54	Helical path: radius, period and pitchResolve the velocity into components along and across the field, explain why the path is a helix, and write the radius, the period and the pitch, with a sketch of the helix about the field direction.	Derivation	2	never		Never asked
55	Numericals: radius from kinetic energy or accelerating potentialFind the radius when the particle is described by its kinetic energy or the potential difference that accelerated it, and compare the radii of proton, deuteron, alpha particle or electron for the same K, the same V or the same momentum.	Numericals	3	never		Never asked
56	Numericals: radius and pitch of a helical pathFor a charge entering the field at an angle, compute the radius of the helix from the perpendicular velocity component and the pitch (or the distance covered in a number of turns) from the parallel component.	Numericals	2	never		Never asked
57	Numericals: undeflected beam, v = E/BUse the no-deflection condition to find the speed, the field needed or its direction, and combine it with the accelerating potential or the circular radius to get q/m or the mass of the particle.	Numericals	2	never		Never asked
58	Derive F = I l B sin(theta) on a conductorStart from the force on one drifting electron, multiply by the number of free electrons in the length, use I = n e A v_d to reach the force on the conductor, write the vector form, state Fleming's left-hand rule (or right-hand palm rule 2) for direction, and explain why a neutral wire still feels a force only when current flows.	Derivation	3	never		Never asked
59	Numericals: rod balanced by the magnetic forceSet the magnetic force on a current-carrying rod equal to its weight (or to the weight component on a smooth incline) to find the field or current needed, the tension in the supports, and the direction the current must flow.	Numericals	3	never		Never asked
60	B of a finite straight conductor (formula only)Write the formula for B at perpendicular distance r from a straight wire of finite length with a sketch defining the two angles, and reduce it to the infinite wire, a point opposite one end and a point on the perpendicular bisector.	Statement	1	never		Never asked
61	Numericals: B from straight segments (square, triangle)Apply the finite-wire formula to each side of a square or triangular frame to get B at its centre, and use symmetry or unequal branch currents to decide whether the field at the centre of a wire frame cancels.	Numericals	3	never		Never asked
62	Ampere's law: derive B inside a long solenoidDraw the solenoid in section with a rectangular path having one side along the axis inside, show that only that side contributes, count the current enclosed as n x I0, and obtain B inside; add the value at the ends and with an iron core.	Derivation	3	never		Never asked
63	Numericals: force on a loop near a long wireFor a rectangular loop lying beside a long straight wire, find the forces on the near and far sides, show the other two cancel, give the net force and its direction, and say what changes if the loop current is reversed.	Numericals	3	never		Never asked
64	Derive torque on a current loop in uniform BDraw a rectangular loop with its normal at angle theta to B (plus the top view of the couple), find the force on each side, show the net force is zero and two forces form a couple, derive the torque for one turn and N turns, write it with the angle between the plane and the field as well, and state the positions of zero and maximum torque.	Derivation	5	never		Never asked
65	Magnetic moment of a current loop: m = NIADefine the magnetic moment of a coil (as N I A and as the maximum torque in unit field), give its unit and direction by the right-hand rule, say why a current loop is a magnetic dipole, and compute m for given turns, current and area or for a wire bent into a loop.	Statement	1	never		Never asked
66	Numericals: torque direction, orientations and equilibriumFor a loop drawn in several orientations relative to the axes, write the area vector, take I A x B to get the torque with its direction in each case, and pick out the stable and unstable equilibrium positions.	Numericals	3	never		Never asked
67	Maximum torque from a wire of fixed lengthShow that a given length of wire gives the largest torque when bent into a single circular turn held with its plane parallel to the field, and compute that maximum torque.	Numericals	3	never		Never asked
68	Orbital magnetic moment of electron; Bohr magnetonTreat the revolving electron as a current loop to get its magnetic moment in terms of v and r, rewrite it using angular momentum to get the gyromagnetic ratio, then apply Bohr's quantum condition to obtain the Bohr magneton and its value.	Derivation	2	never		Never asked
69	Numericals: magnetic moment of orbiting electronsCompute the magnetic moment of an electron from its speed and orbit radius, and combine the moments of electrons revolving in opposite senses to decide whether the atom has a net moment.	Numericals	2	never		Never asked
70	*Numericals: galvanometer equation N I A B = cphi**Use the balance of deflecting and restoring torque to find the current for a given deflection (largest and smallest measurable), the torsional constant, or the field or coil area.	Numericals	2	never		Never asked
71	Numericals: magnetic moment m = NIA of loops and solenoidsCompute the magnetic moment (with direction) of a coil, solenoid or wire bent into a new shape from turns, current and area, or find the current that makes a coil equivalent to a given magnet.	Numericals	2	never		Never asked
72	Current loop and bar magnet as dipoles: similaritiesList the three ways a current loop behaves like a bar magnet: it sets with m along B, two coaxial loops attract or repel like two magnets, and the field expressions have the same form.	Comparison	2	never		Never asked
73	Effect of cutting or resizing a magnet on its momentWork out the new pole strength and magnetic moment of each piece when a bar magnet is cut along or across its length, or when pole strength and pole separation are scaled by given factors.	Numericals	1	never		Never asked
74	Magnetic lines of force: definition and seven propertiesDefine a magnetic line of force and write its properties: closed loops through the magnet, never intersecting (with the reason), crowding shows field strength, parallel and equidistant in a uniform field, none through a neutral point, any angle at a pole, contraction between unlike poles and repulsion between like poles.	Statement	3	never		Never asked
75	Sketch field lines of bar magnet, solenoid, pole pairsDraw neat field-line patterns with arrows for a bar magnet and for a current-carrying solenoid as closed loops, and for facing unlike poles and facing like poles.	Diagram	2	never		Never asked
76	Solenoid as a bar magnet: evidence and polarity ruleExplain the observations showing that a current-carrying solenoid acts as a bar magnet (rests north-south, its ends attract and repel like poles), state the clockwise/anticlockwise end rule for polarity, and relate cutting a magnet to cutting a solenoid.	Give reason	2	never		Never asked
77	Compare bar magnet and current-carrying solenoid (table)Write a five-row table contrasting a bar magnet and a current-carrying solenoid on source of magnetism, poles, field pattern, what the dipole moment depends on, and whether strength and polarity can be changed.	Comparison	2	never		Never asked
78	Numericals: field of a short bar magnet, axial and equatorialCalculate the magnitude and direction of B at a given distance on the axis or equatorial line of a short magnet, or find the distance or moment from a given field, converting between tesla and gauss.	Numericals	2	never		Never asked
79	Numericals: combined field of two short magnetsFind the resultant field at a point due to two short magnets (collinear with facing poles, or on perpendicular lines) by adding their axial or equatorial fields as vectors, or compare their moments when a compass between them stays undeflected.	Numericals	2	never		Never asked
80	Force and torque on a dipole: uniform versus non-uniform fieldExplain why a magnet in a uniform field feels a torque but no net force, why it feels both in a non-uniform field, why an iron nail near a magnet is attracted, and why a magnet's own field exerts no torque on it.	Give reason	2	never		Never asked
81	Definitions and units: B, M, H, mu, mu_r, chi_mDefine magnetic induction (flux density), intensity of magnetisation, magnetic intensity, permeability, relative permeability and susceptibility, write the defining relation and SI unit of each, give tesla-gauss and oersted conversions, and state the sign and size of chi_m for the three classes.	Statement	2	never		Never asked
82	Behaviour of dia and para specimens in a magnetic fieldDescribe with sketches how a diamagnetic and a paramagnetic sample behave: how a suspended rod sets between poles, the shape of a liquid in a watch glass for near and far pole pieces, the level in a U-tube arm, the spread of a gas, and the modified field-line pattern through a specimen in a uniform field; also how soft-iron rings shield a region.	Diagram	2	never		Never asked
83	Numericals: Curie's law for magnetisation and susceptibilityScale the magnetic moment, magnetisation or susceptibility of a paramagnetic sample from one field and temperature to another using proportionality to B/T (or 1/T for susceptibility).	Numericals	2	never		Never asked
84	Explain diamagnetism and paramagnetism on the atomic modelExplain how orbital and spin motion give an atom its magnetic moment, why paired electrons give zero net moment and an induced opposing moment in a field (diamagnetism, independent of temperature), and why atoms with a permanent moment align partly along the field against thermal agitation (paramagnetism, weaker on heating), with the random and aligned dipole sketches.	Give reason	3	never		Never asked
85	Domain theory of ferromagnetism with diagramsExplain ferromagnetism by domains: what a domain is and its size, why an unmagnetised piece has zero net moment, the two ways magnetisation grows in a field (boundary displacement in weak fields, domain rotation in strong fields), and why some magnetism remains when the field is removed, with the three four-domain sketches.	Give reason	5	never		Never asked
86	Compare Coulomb's law and Biot-Savart lawWrite a two-column list of the similarities (both inverse-square, both give a field from a source) and the differences (scalar charge against vector current element, angle dependence, field along r against field perpendicular to dl and r).	Comparison	3	never		Not in syllabus
87	B inside and outside a thick wire or pipeApply Ampere's law to circular paths inside and outside a wire carrying uniformly distributed current to say how B varies with distance from the axis, and sketch the B against r graph (also for a hollow pipe).	Give reason	2	never		Not in syllabus
88	Compare electric and magnetic forces between chargesWrite the electric and magnetic forces between two moving charges, form their ratio to show the electric force is far larger at ordinary speeds, and use it to explain why a very fast electron beam starts to converge.	Comparison	2	never		Not in syllabus
89	Pivoted-coil (Weston) galvanometer and the shuntDescribe how the pivoted-coil type differs from the suspended-coil type (pivots, hair springs, pointer and scale, portable but less sensitive), and say what a shunt is and why it is put across a galvanometer.	Device	2	never		Not in syllabus
90	Numericals: meter resistance changes the circuit readingIn a circuit containing a real ammeter or voltmeter, include the meter's own resistance (shunted coil, or voltmeter in parallel with the resistor) to find the actual current or the true value of the resistance being measured.	Numericals	2	never		Not in syllabus
91	Derive far axial field of a finite solenoidIntegrate the axial field of the ring elements of a solenoid of length 2l and radius a, apply r >> a and r >> l, and show the result equals the axial field of a short bar magnet of moment m = (n 2l) I pi a^2.	Derivation	3	never		Not in syllabus
92	Derive potential energy of a magnet, U = -m.BIntegrate the work dW = m B sin(theta) d(theta) done in turning the magnet from theta1 to theta2, choose zero potential energy at 90 deg to get U, write it as a dot product, and state the orientations of minimum (stable) and maximum (unstable) energy and the work for a 180 deg turn.	Derivation	3	never		Not in syllabus
93	Numericals: work to rotate a magnet and its potential energyCalculate the work needed to turn a magnet or coil between two orientations in a uniform field, the potential energy in the stable and unstable positions, or the energy change on reaching equilibrium.	Numericals	2	never		Not in syllabus
94	Saturation magnetisation and thermal versus magnetic energyFind the maximum (saturation) magnetic moment or magnetisation from the number of atomic dipoles and the moment of each, and compare (3/2) k T with m B to judge whether a given field can bring a paramagnetic gas near saturation.	Numericals	3	never		Not in syllabus
95	Superconductors as perfect diamagnetsState that a superconductor has zero resistance below a definite temperature, expels all field lines, and has susceptibility -1 and relative permeability zero, showing the second from B = mu0 (H + M) = 0.	Statement	1	never		Not in syllabus
96	Explain demagnetisation: hammering, heating, alternating currentExplain on the domain picture why hammering or heating a magnet above its Curie temperature destroys its magnetism and why it does not return on cooling in a field-free space, and describe demagnetising a rod in a solenoid carrying a gradually reduced alternating current.	Give reason	2	never		Not in syllabus
97	Hysteresis loss: cause and area of the loopExplain why the energy spent in magnetising a ferromagnetic material is not fully recovered, state that the energy lost as heat per unit volume per cycle equals the area of the hysteresis loop, and say why a material with a narrow loop is chosen for cores.	Give reason	2	1 paper	2002	Not in syllabus

This list was made from the textbook chapters and 25 years of board questions.

The 10 topics Physics papers ask most

Counted on the board papers from 2018 to the 2027 specimen paper, which every unit has been checked against.

1.Numericals: peak, rms, mean, frequency from an ac equationP4 Electromagnetic Induction and Alternating Currents · asked 7 times since 2018
2.Uses and special properties of each region (table)P5 Electromagnetic Waves · asked 7 times since 2018
3.State Bohr's postulates for the hydrogen atomP8 Atoms and Nuclei · asked 7 times since 2018
4.Magnetic force on a moving charge and Lorentz forceP3 Magnetic Effects of Current and Magnetism · asked 6 times since 2018
5.Numericals: average power and power factorP4 Electromagnetic Induction and Alternating Currents · asked 6 times since 2018
6.Doping, n-type and p-type, donors, acceptors, carriersP9 Electronic Devices · asked 6 times since 2018
7.Numericals: two-loop network with two batteries (Kirchhoff)P2 Current Electricity · asked 5 times since 2018
8.Derive B at the centre of a circular loopP3 Magnetic Effects of Current and Magnetism · asked 5 times since 2018
9.Numericals: B at the centre of a circular coilP3 Magnetic Effects of Current and Magnetism · asked 5 times since 2018
10.Ampere's law: derive B near a long straight wireP3 Magnetic Effects of Current and Magnetism · asked 5 times since 2018

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