Page 45 - Q & A STPM 2022 Physics

Physics Semester 3 STPM Chapter 21 Sound Waves
Question 9

A tube P is closed at one end and open at the other end. Another tube Q is
open at both ends. The tubes P and Q are of the same length. What is the ratio
of the frequencies of the first overtone of tube P to tube Q?
Penerbitan Pelangi Sdn Bhd. All Rights Reserved.
A 1 C 2
4 3
B 1 D 3
2 4

Answer: D

N A A
N
I
A A A
N N

Tube P: l = 3   = 3v
λ 1
4
4f 1
v
Tube Q: l = 4   = f 2
λ 2
4
f 1 = 3
f 2 4
Question 10
Three successive resonance frequencies of a tube are 450 Hz, 750 Hz and
1050 Hz. Which of the following is the correction deduction about the tube and
its fundamental frequency?
Tube Fundamental frequency
A Closed at one end and open at the other 150 Hz
B Closed at one end and open at the other 300 Hz
C Open at both ends 150 Hz
D Open at both ends 300 Hz

Answer: A
Resonance frequencies of a tube closed at one end and open at the other are Semester
f 0 , 3f 0 , 5f 0 , 7f 0 , …
Difference of frequencies between successive overtones = 2f 0 = (750 – 450) Hz
= 300 Hz 3

405

021 STPM Q&A Physics T3.indd 405 17/02/2022 10:24 AM