Class 9 Propagation of Sound Waves Mock Test (ICSE)

Topics in Propagation of Sound Waves

• Sound needs a medium
• Longitudinal and transverse waves
• Amplitude, frequency, wavelength and V = f lambda
• Speed of sound in different media
• Infrasonic and ultrasonic sound and their uses

Propagation of Sound Waves practice questions with answers

1. Q1Multiple choice·1 mark
   In a transverse wave, the particles of the medium vibrate:

   1. (a)In circular paths about the equilibrium position
   2. (b)Parallel to the direction of wave propagation
   3. (c)Perpendicular to the direction of wave propagation
   4. (d)Randomly in all directions
   Show answer and step marks

   1. Correct option: (c) Perpendicular to the direction of wave propagation. In transverse waves, particle displacement is perpendicular to the direction of wave travel.+1

   Answer: (c)
2. Q2Multiple choice·1 mark
   The speed of sound is generally maximum in which of the following media at a given temperature?

   1. (a)Water
   2. (b)Iron
   3. (c)Air
   4. (d)Hydrogen gas
   Show answer and step marks

   1. Correct option: (b) Iron. Sound travels fastest in solids due to high elasticity and close packing of molecules compared to liquids and gases.+1

   Answer: (b)
3. Q3Multiple choice·1 mark
   A wave has a frequency of $500\text{ Hz}$ and a wavelength of $0.4\text{ m}$. The speed of the wave is:

   1. (a)$125\text{ m s}^{-1}$
   2. (b)$500\text{ m s}^{-1}$
   3. (c)$1250\text{ m s}^{-1}$
   4. (d)$200\text{ m s}^{-1}$
   Show answer and step marks

   1. Correct option: (d) $200\text{ m s}^{-1}$. Using the relation $V = f\lambda$, we substitute $f = 500\text{ Hz}$ and $\lambda = 0.4\text{ m}$ to get $V = 500 \times 0.4 = 200\text{ m s}^{-1}$.+1

   Answer: (d)
4. Q4Multiple choice·1 mark
   During the bell jar experiment, when air is completely pumped out of the jar, the electric bell inside is seen ringing but its sound is not heard. This proves that:

   1. (a)Sound travels fastest in a vacuum
   2. (b)Sound waves are electromagnetic waves
   3. (c)Sound requires no medium if the amplitude is high
   4. (d)Sound cannot travel through a vacuum
   Show answer and step marks

   1. Correct option: (d). Sound is a mechanical wave and requires material particles for its propagation, hence it cannot travel through a vacuum.+1

   Answer: (d)

More Class 9 Physics mock tests