IB Physics SL C.2 Wave model Questions

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In IB Physics SL C.2, use particle-motion sketches to distinguish wave types, calculate speed or wavelength from v=fλ, and explain how sound or light propagates.

81 questions in this syllabus scope, with question parts counted together.

Exam points & syllabus

Exam points

Define wave type by comparing local oscillation with energy propagation: transverse is perpendicular; longitudinal is parallel.
Describe a travelling wave as energy transferred by a propagating disturbance while local particles or fields oscillate.
Explain sound in air as a longitudinal travelling pattern of compressions and rarefactions; a standing sound wave also has longitudinal particle motion.
Locate compression or rarefaction from neighbouring particle displacements: converging neighbours compress; separating neighbours rarefy.
Infer local particle direction by following a travelling profile; distinguish signed longitudinal displacement from the up/down direction of its graph.
Read amplitude from equilibrium and wavelength from matching spatial repeats; in a particle-position diagram use the equilibrium coordinate spacing.
Read a full period from a time trace or cycle count, convert timing units and use f=1/T; keep temporal and spatial graph axes distinct.
Combine v=fλ=λ/T with spatial and time graphs to calculate wave speed, wavelength, frequency or period, retaining units and required precision.
Find wave speed from the translation of two spatial profiles and elapsed time; use the period condition to choose the corresponding shifted feature.
Relate echo repeats to round-trip travel, or use equal source distances with two wave speeds to interpret an arrival-time difference.
Across a medium boundary keep source frequency fixed and use the changed speed to compare wavelength; read the stated or diagrammed refraction context.
Use a supplied standing-wave pattern to obtain wavelength before v=fλ: adjacent nodes are λ/2 and a first-harmonic string has λ=2L.
When interference geometry first determines wavelength, calculate the wave frequency from c=fλ using the correct maximum order.
Compare particle and propagation speeds: an oscillating particle travels 4A per cycle, while the disturbance propagates at v=fλ.
Use fractional wavelength and period to locate a particle later or sketch its oscillation trace; include a given reference-particle motion when needed.
Describe EM waves using perpendicular electric and magnetic field oscillations, transverse propagation and the ability to travel through vacuum at c.
Keep electric and magnetic fields at right angles when an EM wave enters the specified transparent medium.
Use approximate electromagnetic scales: visible wavelengths are of order 10^-7 m, ultraviolet can have order-10^15 Hz frequency, and X-rays are higher.
Use distance=ct for a direct radio link or satellite signal, converting units and distinguishing one-way propagation from a reflected round trip.
When a material wave-speed relation is supplied, determine speed from the wave data first, then rearrange the given relation with its stated units.

Covered syllabus points

C.2.1—Transverse and longitudinal travelling waves C.2.2—Wave quantities and wave equation C.2.3—Nature of sound waves C.2.4—Nature of electromagnetic waves C.2.5—Mechanical and electromagnetic wave models

[Maximum number: 2]

Outline what is meant by a travelling wave.

[Maximum number: 1]

This question is in two parts. Part 1 is about the nuclear model of the atom and radioactive decay. Part 2 is about waves.

Part 1 Nuclear model of the atom and radioactive decay

Part 2 Waves
Two waves, A and B, are travelling in opposite directions in a tank of water. The graph shows the variation of displacement of the water surface with distance along the wave at a particular instant.

State the amplitude of wave A.

5 mm or 5.0 mm ;
units are required Allow other units, eg: $5 / 5.0 \times 10^{-3} \mathrm{~m}$ .

[Maximum number: 1]

This question is in two parts. Part 1 is about a thermistor circuit. Part 2 is about vibrations and waves.
Part 1 Thermistor circuit
The circuit shows a negative temperature coefficient (NTC) thermistor X and a $100 \mathrm{k} \Omega$ fixed resistor R connected across a battery.

The battery has an electromotive force (emf) of 12.0 V and negligible internal resistance.

Part 2 Vibrations and waves

The cone and dust cap D of a loudspeaker L vibrates with a frequency of 1.25 kHz with simple harmonic motion (SHM).

The sound waves from the loudspeaker travel in air with speed $330 \mathrm{~m} \mathrm{~s}^{-1}$ .

Calculate the wavelength of the sound waves.

[Maximum number: 3]

The battery has an electromotive force (emf) of 12.0 V and negligible internal resistance.

Part 2 Vibrations and waves

The cone and dust cap D of a loudspeaker L vibrates with a frequency of 1.25 kHz with simple harmonic motion (SHM).

The sound waves from the loudspeaker travel in air with speed $330 \mathrm{~m} \mathrm{~s}^{-1}$ .

Describe the characteristics of sound waves in air.

[Maximum number: 1]

Electromagnetic waves

always obey an inverse square law.

are made up of electric and magnetic fields of constant amplitude.

always travel at the same speed in a vacuum.

are always polarized.

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