What produces sound?

Sound is produced by vibrations - the periodic to and fro motion of objects.

True or False: Sound can travel through vacuum.

False. Sound cannot travel through vacuum because it needs a medium to propagate.

The object that creates sound is called the _____ of sound.

Source

Which type of waves are sound waves?
A) Transverse waves
B) Longitudinal waves
C) Electromagnetic waves
D) Light waves

B) Longitudinal waves

How do humans produce sound?

Humans produce sound through vibration of vocal cords in the voice box or larynx.

What happens to sound in the vacuum bell jar experiment?

Sound becomes fainter as air is removed and disappears in near-vacuum conditions.

In sound waves, particles vibrate _____ to the direction of wave propagation.

Parallel

What are compressions in sound waves?

Compressions are regions of higher air density where particles are pushed together.

True or False: Sound particles travel from source to listener.

False. Only energy travels; particles vibrate about their mean positions without traveling.

What is wavelength represented by the Greek letter λ?

Distance between two consecutive crests or troughs in a wave.

If 20 oscillations occur in 4 seconds, what is the frequency?

Frequency = 20 ÷ 4 = 5 Hz

The relationship between frequency (ν) and time period (T) is ν = _____.

1/T

Which medium allows sound to travel fastest?
A) Gases
B) Liquids
C) Solids
D) Vacuum

C) Solids

What is the formula relating wave speed, wavelength, and frequency?

V = λ × ν (speed = wavelength × frequency)

True or False: Sound travels faster at higher temperatures.

True. Speed of sound increases with temperature and humidity.

Human perception of frequency is called _____.

Pitch

What is the audible frequency range for humans?

20 Hz to 20,000 Hz (20 kHz)

Sound waves below 20 Hz are called _____ waves.

Infrasonic

Which has higher pitch - a whistle or thunder?
A) Whistle
B) Thunder
C) Both same
D) Cannot determine

A) Whistle

What determines how loud a sound appears to humans?

Amplitude of the sound wave determines perceived loudness.

For an echo to be heard distinctly, minimum time gap needed is _____.

0.1 seconds

If echo returns after 0.4 s and sound speed is 340 m/s, find distance.

Distance = (340 × 0.4) ÷ 2 = 68 meters

What is reverberation in acoustics?

Multiple reflections of sound in large halls causing sound to persist after source stops.

True or False: Soft surfaces reflect sound better than hard surfaces.

False. Hard, smooth surfaces reflect sound well; soft surfaces absorb sound.

Which animals use echolocation for navigation?
A) Bats and dolphins
B) Dogs and cats
C) Birds and fish
D) Elephants and mice

A) Bats and dolphins

What does SONAR stand for?

Sound Navigation and Ranging

Ultrasonic waves are used in medical _____ to image internal organs.

Ultrasonography

Why can't astronauts hear each other directly in space?

Space is near vacuum with no medium for sound wave propagation.