IB Physics HL C 2 Wave Model Questions

Practise IB Physics HL C.2 by reading wave diagrams, using v = fλ with wave data, and explaining how sound and electromagnetic waves propagate.

Exam points

Distinguish transverse and longitudinal waves by comparing particle oscillation with energy propagation.
Read displacement graphs and use v = fλ = λ/T to calculate wave speed, wavelength, frequency or period.
Describe sound as a longitudinal mechanical wave with particle motion, compressions and rarefactions.
Compare sound and light by wave type and whether each can propagate through a vacuum.
Describe travelling-wave energy transfer as propagation through oscillations of a medium or field.
Use amplitude, speed and area data to compare wave power or intensity in mechanical-wave contexts.

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: 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.

The length of the pipe is 1.20 m .

[ 2 ]

(i)

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

[ 2 ]

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

Marking guidance:

Allow ECF from incorrect wavelength in bii)

[Maximum number: 6]

(a)

A spring, such as that in (a), is stretched horizontally and a longitudinal travelling wave is set up in the spring, travelling to the right.

[ 6 ]

(i)

Describe, in terms of the propagation of energy, what is meant by a longitudinal travelling wave.

[ 2 ]

(ii)

The graph shows how the displacement x of one coil C of the spring varies with time t.

Figure for Question (ii) — IB Physics HL

The speed of the wave is $3.0 \mathrm{~cm} \mathrm{~s}^{-1}$ . Determine the wavelength of the wave.

[ 2 ]

frequency $=\left(\frac{1}{T}=\frac{1}{0.80}=\right) 1.25 \mathrm{~Hz}$ ;
wavelength $=\frac{v}{f}=\frac{3.0}{1.25}=2.4 \mathrm{~cm}$ or $2.4 \times 10^{-2} \mathrm{~m}$ ;

(iii)

Draw, on the graph in (c)(ii), the displacement of a coil of the spring that is 1.8 cm away from C in the direction of travel of the wave, explaining your answer.

[ 2 ]

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Covered syllabus points

Question 1

Question (a)

Question (b)

Question (i)

Question 2

Question (a)

Question (i)

Question (ii)

Question (iii)