IB Physics SL C 2 Wave Model Questions

Practise IB Physics SL C.2 by using wave descriptions, superposition, standing waves, diffraction and interference to interpret evidence.

Exam points

define and relate wavelength, frequency, period and wave speed for travelling waves, including transverse and longitudinal descriptions
interpret displacement-time and position graphs using amplitude, phase, direction of particle motion and wave relationships
explain and analyse wave behaviour including superposition, reflection, refraction, diffraction, interference and standing-wave evidence

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

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Study C.2 Wave model conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

[Maximum number: 4]

(a)

Outline what is meant by a travelling wave.

[ 2 ]

(b)

A loudspeaker emits sound of frequency 210 Hz into a pipe with one open and one closed end. The diagram shows a representation of the standing wave established in the pipe.

[ 2 ]

(i)

Calculate the speed of sound in the pipe stating the answer to an appropriate number of significant figures.

[ 2 ]

$c=\ll \lambda f=1.60 \times 210 \Rightarrow \gg 336$ OR $340 \ll \mathrm{~m} \mathrm{~s}^{-1} \gg$
Any answer to 2 OR 3 s.f.

Marking guidance:

Allow ECF from incorrect wavelength in bii)

[2]

[Maximum number: 6]

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

(a)

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.

[ 1 ]

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

(b)

Wave A has a frequency of 9.0 Hz . Calculate the velocity of wave A .

[ 2 ]

wavelength $=8.0 \mathrm{~cm}$ or 8 cm ;
(accept clear substitution in MP2 for this mark) $v=(f \lambda=) 9 \times 8=72 \mathrm{~cm} \mathrm{~s}^{-1}$ ;
units are required

(c)

Deduce the frequency of wave B.

[ 3 ]

wavelength $=3.9 \mathrm{~cm}$ ;
(accept answers in the range of 3.8 to 4.0 cm )
frequency $=\left(\frac{72}{3.9}=\right) 18$ ;
Hz or $\mathrm{s}^{-1}$ ;

[Maximum number: 4]

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.

(a)

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

[ 4 ]

(i)

Calculate the wavelength of the sound waves.

[ 1 ]

(ii)

Describe the characteristics of sound waves in air.

[ 3 ]

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Covered syllabus points

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