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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P7 Dual Nature of Radiation and Matter
All the topics in Physics: Dual Nature of Radiation and Matter
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.
18 topics shown
| # | Topic | Type | Marks | Times asked | Last asked | Status |
|---|---|---|---|---|---|---|
| 1 | De Broglie hypothesis, relation and matter wavesState the de Broglie hypothesis (a wave is associated with every moving material particle), write the de Broglie relation naming each symbol, define matter waves, say what the wavelength depends on (momentum, so mass and velocity; not size or charge), and why it is not noticed for everyday objects. | Statement | 1 | 5 papers | Specimen 2027 | Asked |
| 2 | Predict effect of changing intensity, frequency or metalFor a stated change (intensity raised, frequency raised, a metal of different work function) or for a picture or data on several metals, state what happens to photocurrent, stopping potential, Emax and threshold frequency, each with a one-line reason from Emax = h nu - W0 = e Vs. | Give reason | 3 | 4 papers | Specimen 2027 | Asked |
| 3 | Compare de Broglie wavelengths: ratios and dependenceWithout a full calculation, decide how lambda changes when kinetic energy, speed or accelerating potential is changed by a factor; rank electron, proton, deuteron and alpha particle for the same speed, the same kinetic energy or the same accelerating potential; and compare kinetic energies or momenta of two particles from a given ratio of wavelengths, writing the proportionality used. | Give reason | 2 | 4 papers | Specimen 2027 | Asked |
| 4 | Numericals: Einstein's equation (Emax, Vs, threshold, work function)Given some of wavelength or frequency, work function, threshold frequency or wavelength, stopping potential and maximum speed, find the others; decide by calculation whether a metal emits at all by comparing photon energy with its work function; keep one unit system (all J or all eV) through the working. | Numericals | 2 | 3 papers | Specimen 2027 | Asked |
| 5 | Numericals: photon energy in joule and electronvoltFrom a given wavelength or frequency compute the energy of one photon in J and convert it to eV (and the reverse); rank colours or regions by photon energy; find the number of photons emitted per second by a source of given power. | Numericals | 2 | 3 papers | 2026 | Asked |
| 6 | Stopping potential versus frequency graph: draw and interpretPlot stopping potential against frequency: a straight line that starts on the frequency axis at the threshold frequency f0, with its dashed extension meeting the Vs axis at -W0/e; label both axes with units, f0, the slope and the intercept, state what each gives, and draw the lines for two metals on one graph (parallel, different f0). | Graph | 2 | 3 papers | 2026 | Asked |
| 7 | Davisson-Germer experiment: qualitative description and conclusionDescribe in words, with a rough labelled sketch, how a beam of electrons accelerated through a known potential difference strikes a nickel crystal while a movable detector measures the intensity scattered at different angles; state the observation (a sharp maximum at one particular angle and voltage, as in diffraction) and the conclusion that electrons are diffracted, so moving particles have a wave nature, in agreement with de Broglie's relation. | Statement | 1 | 3 papers | 2026 | Asked |
| 8 | Photoelectric effect: definitions and units clusterDefine in one sentence each: photoelectric effect, photoelectrons, work function, threshold frequency, threshold wavelength and stopping potential, giving the SI unit of each quantity and the relations that link them. | Statement | 2 | 3 papers | 2025 | Asked |
| 9 | Explain the experimental facts by photons; wave theory failsTake each experimental fact in turn (threshold frequency, maximum kinetic energy set by frequency and not by intensity, current proportional to intensity, no time lag), explain it from the photon picture and Einstein's equation, say in one line why the wave theory cannot explain it, and end with the conclusion that light behaves as particles in this effect. | Give reason | 3 | 2 papers | Specimen 2027 | Asked |
| 10 | Derive de Broglie wavelength from kinetic energy, accelerating potentialStarting from lambda = h/p and K = p^2/(2m), obtain lambda in terms of kinetic energy; then for a charge q accelerated from rest through a potential difference V (K = qV) obtain lambda in terms of V, and the numerical form for an electron. | Derivation | 2 | 2 papers | Specimen 2027 | Asked |
| 11 | Photon momentum: relation and numericalsState how the momentum of a photon is related to its energy, frequency and wavelength, and compute the momentum from a given energy, frequency or wavelength (and the reverse), with the unit. | Numericals | 1 | 2 papers | 2026 | Asked |
| 12 | Hertz and Lenard: experimental facts and conclusionsState what Hertz noticed (sparks across the gap of his detector passed more easily when ultraviolet light fell on the metal electrode) and what Lenard found (ultraviolet light on the emitter plate of an evacuated tube gives a current that stops the moment the light is cut off), then list the experimental facts: photocurrent is proportional to intensity; stopping potential and maximum kinetic energy do not depend on intensity; maximum kinetic energy rises linearly with frequency; there is no emission below a threshold frequency whatever the intensity; emission starts with no time lag. | Statement | 2 | 2 papers | 2025 improvement | Asked |
| 13 | Find Planck's constant and work function from Vs-f graphFrom a given graph or table of stopping potential against frequency, read two well-separated points (or the two intercepts), compute the slope, multiply by e to get h with its unit, and find the work function from h f0 or from e times the size of the Vs-axis intercept, in J and in eV. | Numericals | 3 | 2 papers | 2025 improvement | Asked |
| 14 | Photon picture: Planck's idea and photon propertiesState Planck's quantum idea and how Einstein extended it to light (light of frequency nu travels as packets called photons, each of energy h nu), then list the properties of a photon: energy, momentum, speed c in vacuum, zero rest mass, no charge, intensity decided by the number of photons per second per unit area, and that in a collision with an electron a photon gives up all of its energy or none of it. | Statement | 1 | 1 paper | Specimen 2027 | Asked |
| 15 | Wave-particle duality: evidence for each nature (table)Draw a two-by-two table for radiation and for matter giving the phenomena that show wave nature (radiation: interference, diffraction, polarisation; matter: electron diffraction) and particle nature (radiation: photoelectric effect; matter: it possesses momentum p and kinetic energy), and state in one sentence what dual nature means. | Comparison | 1 | 1 paper | 2025 | Asked |
| 16 | Einstein's photoelectric equation with meaning of termsWrite Einstein's equation from energy conservation for one photon absorbed by one electron (photon energy = work function + maximum kinetic energy), name every symbol, and rewrite it in terms of threshold frequency, of wavelengths, and of stopping potential. | Statement | 2 | 1 paper | 2018 | Asked |
| 17 | Numericals: de Broglie wavelength of a moving particleCompute the de Broglie wavelength of a particle from its mass and speed, from its kinetic energy (in J or eV), or for an electron, proton or alpha particle accelerated through V volts; and the reverse (find speed, kinetic energy or V from a given wavelength). | Numericals | 2 | never | Never asked | |
| 18 | Graphs of photocurrent against intensity and collector potentialSketch and label three graphs: photocurrent against intensity (straight line through the origin); photocurrent against collector potential for two intensities at one frequency (same stopping potential, different saturation currents); photocurrent against collector potential for two or three frequencies at one intensity (same saturation current, larger stopping potential for the higher frequency). Mark saturation current and stopping potential on each. | Graph | 2 | never | Not in syllabus |
This list was made from the 2027 syllabus and checked with 9 board papers, including the 2027 specimen paper. It is not yet checked with the textbook.
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