Waves extension IB DP Physics Study Notes - 2025 Syllabus
Standing waves IB DP Physics Study Notes
Standing waves IB DP Physics Study Notes at IITian Academy focus on specific topic and type of questions asked in actual exam. Study Notes focus on IB Physics syllabus with Students should understand
the nature and formation of standing waves in terms of superposition of two identical waves travelling
in opposite directions
Standard level and higher level: 4 hours
Additional higher level: There is no additional higher level content .
- IB DP Physics 2025 SL- IB Style Practice Questions with Answer-Topic Wise-Paper 1
- IB DP Physics 2025 HL- IB Style Practice Questions with Answer-Topic Wise-Paper 1
- IB DP Physics 2025 SL- IB Style Practice Questions with Answer-Topic Wise-Paper 2
- IB DP Physics 2025 HL- IB Style Practice Questions with Answer-Topic Wise-Paper 2
The nature of standing waves
- The principle of superposition yields a surprising sum for two identical waves traveling in opposite directions.
- Snapshots of the blue and the green waves and their red sum shows a wave that appears to not be traveling.
- Because the resultant red wave is not traveling it is called a standing wave.
Nodes and antinodes
- The standing wave has two important properties.
- It does not travel to the left or the right as the blue and the green wave do.
- Its “lobes” grow and shrink and reverse, but do not go to the left or the right.
- Any points where the standing wave has no displacement is called a node (N).
- The lobes that grow and shrink and reverse are called antinodes (A).
IB Physics Standing waves Exam Style Worked Out Questions
Question
Diagram 1 shows the variation with position of the displacement of a standing wave formed on a string.
Diagram 2 shows the variation with position of the displacement of a travelling wave moving to the right along a string.
Points $P, Q, R$ and $S$ are points on the string.
What is the phase difference between $\mathrm{P}$ and $\mathrm{Q}$ and the phase difference between $\mathrm{R}$ and $\mathrm{S}$ ?
▶️Answer/Explanation
Ans:C
Question
A standing wave is formed in a pipe open at one end and closed at the other. The length of the pipe is L and the speed of sound in the pipe is V.
\(n\) is a positive integer.
What expression is correct about the frequencies of the harmonics in the pipe?
A. \(\frac{(2 n-1) V}{2 L}\)
B. \(\frac{(2 n-1) V}{4 L}\)
C. \(\frac{n V}{2 L}\)
D. \(\frac{n V}{4 L}\)
▶️Answer/Explanation
Ans:B
The general frequency for closed at one end and open to other is ,
\(f_n=\frac{n \cdot w}{4 L} \quad n\)-odd Number and even Harmonics are not present in this.
But in question $n$ is given positive number which it has even as well as odd to , so we have to exclude the even one , and for that we will replace n to $2n+1/2n-1$
\(f_n=\frac{2n+1 \cdot w}{4 L}\) or \(f_n=\frac{2n-1 \cdot w}{4 L}\)
Correct match option – B