Acoustics Chapter Quiz

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Questions and Answers

What is the relationship between frequency ($v$) and time period ($T$)?

$v = T^2$

$v = 1/T$ (correct)

$v = \sqrt{T}$

$v = T$

What determines the loudness of a sound?

Pitch

Time Period

Frequency

Amplitude (correct)

What is the SI unit for the time period ($T$) of a sound wave?

Hertz (Hz)

Second (s) (correct)

Pascal (Pa)

Meter (m)

What is 'pitch' a measure of?

How the brain interprets the frequency of sound (B) Signup and view all the answers

If two identical violins are played in the same room, but one sounds louder than the other, what wave characteristic is primarily different?

Amplitude (A) Signup and view all the answers

A sound wave has a short time period. What can be inferred about its frequency and pitch?

High frequency, high pitch (C) Signup and view all the answers

Consider two sound waves traveling through the air. Wave X has twice the amplitude of Wave Y. How does the energy of Wave X compare to Wave Y?

Wave X has four times the energy of Wave Y. (C) Signup and view all the answers

Two different instruments, a trumpet and a clarinet, play the same note (same pitch) at the same loudness. What wave property MUST be nearly identical for both sounds, and what property is most likely different?

Identical: Frequency; Different: Waveform (A) Signup and view all the answers

What is the primary cause of the sound produced by the human voice?

Vibrations in the vocal cords (C) Signup and view all the answers

What is the term for a region of high pressure created by a vibrating object moving forward?

Compression (D) Signup and view all the answers

What is required for sound to propagate?

A medium (C) Signup and view all the answers

Which of the following best describes how sound travels through a medium?

Vibrations are passed between particles of the medium. (C) Signup and view all the answers

Why don't we typically hear a sound when a bird flaps its wings?

The vibrations are too low in frequency to be audible. (E) Signup and view all the answers

What is the relationship between pressure and the number of particles in a medium when discussing sound?

Higher pressure corresponds to a greater number of particles. (D) Signup and view all the answers

Imagine a scenario where you are submerged underwater and someone strikes a metal object. How the sound propagation underwater will be different from hearing it in air?

Sound will travel faster and potentially be heard at a greater distance compared to air. (B) Signup and view all the answers

Consider two identical sound waves, one traveling through air at sea level and the other through air at a high altitude. Assuming all other conditions are the same, how would the compressions and rarefactions differ between the two waves?

The compressions would be denser and rarefactions less dense at sea level. (D) Signup and view all the answers

What causes the propagation of sound in a medium?

Propagation of density or pressure variations. (D) Signup and view all the answers

In longitudinal waves, how do the particles of the medium move in relation to the direction of wave propagation?

Parallel to the direction of propagation. (A) Signup and view all the answers

What is the primary difference between longitudinal and transverse waves?

Longitudinal waves involve particle movement parallel to wave direction, while transverse waves involve perpendicular movement. (C) Signup and view all the answers

Given a sound wave with a frequency of 220 Hz traveling at a speed of 440 m/s, what is its wavelength?

2 meters (A) Signup and view all the answers

Why would it be difficult to hear a sound on the moon?

The moon has virtually no atmosphere to carry sound waves. (A) Signup and view all the answers

A ringing school bell produces sound due to what physical phenomenon?

The bell vibrating, creating compressions and rarefactions in the surrounding air. (C) Signup and view all the answers

What is the relationship between the speed of sound, its wavelength, and its frequency?

Speed = Wavelength Frequency (D) Signup and view all the answers

Imagine two tuning forks, one vibrating at 440 Hz (A4) and another at 880 Hz (A5). How does the propagation of the sound waves differ between the two forks, assuming identical atmospheric conditions?

The 880 Hz fork's sound waves will have shorter wavelengths, but the same speed. (A) Signup and view all the answers

A person hears a tone of 500 Hz from 450 meters away. What is the time interval between successive compressions reaching the listener?

0.002 seconds (B) Signup and view all the answers

Which statement accurately describes the relationship between loudness and intensity of sound?

Intensity is the amount of sound energy per unit area, while loudness is the ear's subjective response. (D) Signup and view all the answers

A sound wave encounters a boundary between two media with differing densities. Which of the following phenomena is LEAST likely to occur at this boundary?

Complete and lossless transmission, with no change in speed or direction. (B) Signup and view all the answers

Two identical sound sources emit waves in phase. At a certain point in space, the waves arrive with a path length difference of $\lambda/2$, where $\lambda$ is the wavelength. Now, consider two new sound sources where path length difference is $\frac{3\lambda}{2}$. What is the difference between these two scenarios upon the resulting sound intensity?

The first scenario results in destructive interference, while the second also results in destructive interference, thus there is no intensity difference. (B) Signup and view all the answers

Through which of the following media does sound typically travel fastest?

Iron (D) Signup and view all the answers

Why is there a delay between seeing a flash of lightning and hearing the thunder?

Light travels much faster than sound. (D) Signup and view all the answers

Two sound waves have the same intensity, but one is perceived as louder. What is the most likely reason for this?

The ear is more sensitive to the frequency of the perceived louder sound. (A) Signup and view all the answers

Imagine an alien civilization that can manipulate the properties of their atmosphere at will. How could they theoretically maximize the speed of sound in their atmosphere, assuming the temperature remains constant?

By decreasing the density and increasing the bulk modulus of the atmosphere. (B) Signup and view all the answers

What is the minimum distance an obstacle must be from a sound source at 22°C in air for a distinct echo to be heard?

17.2 m (C) Signup and view all the answers

Why is excessive reverberation undesirable in an auditorium?

It makes the sound persist for too long, blurring the original sound. (C) Signup and view all the answers

What causes the rolling sound of thunder?

Successive reflections of sound from multiple surfaces. (A) Signup and view all the answers

What is the primary purpose of megaphones and horns?

To send sound in a specific direction. (B) Signup and view all the answers

If the speed of sound is 342 m/s, how far away is a reflecting surface if an echo is heard in 3 seconds?

513 m (C) Signup and view all the answers

Consider a scenario where the temperature increases, affecting the speed of sound. If the original minimum distance for a distinct echo at temperature $T_1$ was $d_1$, and the new temperature $T_2$ results in a 10% increase in the speed of sound, what is the new minimum distance, $d_2$, required to hear a distinct echo, assuming the time delay remains constant?

$d_2 = 1.1 d_1$ (B) Signup and view all the answers

Why are ordinary sounds with longer wavelengths unsuitable for detecting flaws in metal blocks?

They bend around corners, entering the detector without revealing flaws. (A) Signup and view all the answers

Imagine an auditorium designed to minimize reverberation. Which of the following architectural features would be LEAST effective in achieving this goal?

Employing smooth, hard surfaces for the walls and ceilings. (B) Signup and view all the answers

What is the primary principle behind how ultrasound scanners create images of internal organs?

Reflecting ultrasonic waves from regions with varying tissue densities. (D) Signup and view all the answers

A researcher is studying the multiple reflections of sound in a cave. They emit a short burst of sound and record the arrival times of the first three echoes. The time intervals between the emitted sound and the echoes are $t_1$, $t_2$, and $t_3$, where $t_1 < t_2 < t_3$. Assuming the speed of sound is constant and the cave geometry is complex, what can be inferred about the path lengths ($d_1$, $d_2$, $d_3$) of the sound waves corresponding to these echoes?

The path lengths may or may not be related to each other in a simple way due to the complex geometry (A) Signup and view all the answers

In what scenario would an echocardiogram primarily be employed?

To create images of the heart using reflected ultrasonic waves. (C) Signup and view all the answers

Consider two scenarios: one where ultrasound is used to clean a batch of electronic components with intricate surfaces, and another where it's used to detect a hairline crack in a metal beam supporting a bridge. Which statement accurately contrasts the underlying principles that govern the effectiveness of ultrasound in these two applications?

In cleaning, ultrasound's effectiveness relies on its ability to induce cavitation and dislodge particles, whereas in crack detection, it's the differential reflection of waves at interfaces that matters. (A) Signup and view all the answers

A researcher is developing a new ultrasonic device for detecting cancerous tumors at very early stages. Current ultrasound technology struggles to differentiate between small tumors and healthy tissue due to similar tissue densities. Which of the following strategies represents the MOST innovative approach to enhance the resolution and sensitivity of the new device, enabling it to detect subtle differences in tissue structure and composition at a microscopic level?

Employing harmonic imaging techniques to filter out fundamental frequency echoes and enhance non-linear signals generated by microbubble contrast agents that selectively bind to tumor cells, improving contrast resolution. (D) Signup and view all the answers

Flashcards

Vocal cord vibrations

Sound is produced by vibrations in the vocal cords.

Medium of sound

Matter through which sound is transmitted, can be solid, liquid, or gas.