IB Physics HL C.2 Wave Model Question Bank

Practise IB Physics HL C.2 by analysing wave equations, interference, diffraction, standing modes and extended experimental evidence.

Exam points

Use wave equations and phase relationships to solve multi-step propagation and superposition problems.
Derive or apply interference and diffraction conditions for coherent sources, apertures and gratings.
Interpret standing-wave modes, energy transfer and boundary constraints in HL data.

Covered syllabus points

C.2.1—Wave energy transfer C.2.2—Wave quantities C.2.3—Wave equation C.2.4—Transverse and longitudinal waves C.2.5—Electromagnetic wave speed

[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 ]

$c=\ll \lambda f=1.60 \times 210 \Rightarrow \gg 336$ 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]

(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

C.2 Wave model question 1

Question (a)

Question (b)

Question (i)

C.2 Wave model question 2

Question (a)

Question (i)

Question (ii)

Question (iii)