IB DP Physics Mock Exam SL Paper 2 Set 3 - 2025 Syllabus
IB DP Physics Mock Exam SL Paper 1B Set 3
Prepare for the IB DP Physics Mock Exam SL Paper 2 Set 3 with our comprehensive mock exam set 3. Test your knowledge and understanding of key concepts with challenging questions covering all essential topics. Identify areas for improvement and boost your confidence for the real exam
Question
Graph 1 shows the variation of particle displacement \(d\) with position \(x\) for a travelling sound wave.
(a)
(i) State the wavelength and the period of the sound wave. [2]
(ii) Calculate the speed of the sound wave. [1]
The Doppler effect applies to both sound and light waves.
A car is moving at constant velocity \(v\) between two sources of sound as shown in the diagram. The sources emit sound at \(440\,\text{Hz}\) and at \(540\,\text{Hz}\). The driver hears both sounds at the same frequency.
(b)
(i) Explain which frequency is emitted by source A. [1]
(ii) The spectrum of light received from a galaxy shows a peak at a wavelength of \(659.0\,\text{nm}\). The peak corresponds to an atomic transition in the hydrogen atom that emits a wavelength of \(656.1\,\text{nm}\) when observed in a laboratory on Earth. Calculate the velocity of the galaxy with respect to Earth. [2]
▶️ Answer/Explanation
(a)(i)
Wavelength \(= 0.68\,\text{m}\) (accept \(0.67\) to \(0.70\,\text{m}\)).
Period \(= 0.002\,\text{s}\).
Wavelength \(= 0.68\,\text{m}\) (accept \(0.67\) to \(0.70\,\text{m}\)).
Period \(= 0.002\,\text{s}\).
(a)(ii)
\(v = \dfrac{\lambda}{T} = \dfrac{0.68}{0.002} = 340\,\text{m s}^{-1}\) (allow \(v = 335\)–\(350\,\text{m s}^{-1}\)).
\(v = \dfrac{\lambda}{T} = \dfrac{0.68}{0.002} = 340\,\text{m s}^{-1}\) (allow \(v = 335\)–\(350\,\text{m s}^{-1}\)).
(b)(i)
Source A emits \(440\,\text{Hz}\) because the frequency heard by the driver must be higher from the source the car is moving towards (equivalently: the apparent wavelength decreases).
Source A emits \(440\,\text{Hz}\) because the frequency heard by the driver must be higher from the source the car is moving towards (equivalently: the apparent wavelength decreases).
(b)(ii)
Use \( \dfrac{v}{c} \approx \dfrac{\Delta \lambda}{\lambda} \).
\( \dfrac{v}{c} \approx \dfrac{(659.0\times 10^{-9}) – (656.1\times 10^{-9})}{656.1\times 10^{-9}} \).
\( \dfrac{v}{c} \approx 0.00442 \).
\( v \approx 0.00442\,c \approx 1.33\times 10^{6}\,\text{m s}^{-1} \).
Use \( \dfrac{v}{c} \approx \dfrac{\Delta \lambda}{\lambda} \).
\( \dfrac{v}{c} \approx \dfrac{(659.0\times 10^{-9}) – (656.1\times 10^{-9})}{656.1\times 10^{-9}} \).
\( \dfrac{v}{c} \approx 0.00442 \).
\( v \approx 0.00442\,c \approx 1.33\times 10^{6}\,\text{m s}^{-1} \).