Acoustics

Distance between two consecutive compressions is:
1. $λ$
2. $\frac{λ}{2}$
3. $\frac{λ}{4}$
4. $2 λ$
Sound travels with a speed of 330 m/s. What is the wavelength of sound whose frequency is 550 Hz?
1. 0.7 m
2. 0.8 m
3. 0.6 m
4. 0.4 m
Before playing guitar, guitarist adjust the tension and pluck the string. By doing so, he is adjusting:
1. Intensity of sound
2. Frequency
3. Amplitude
4. Loudness of sound
Velocity of sound in a gaseous medium is 330 m/s. If the pressure is increased by 4 times without causing a change in the temperature, the velocity of sound in the gas is:
1. 330 m/s
2. 660 m/s
3. 165 m/s
4. 990 m/s
Light can travel in vaccum but not sound because of:
1. Speed of sound is very slow than light
2. Light waves are electromangentic in nature
3. Sound waves are electro magnetic in nature
4. Light waves are not electromagnetic in nature
The velocity of sound in air is:
1. Faster in dry air than in moist air
2. Directly proportional to temperature
3. Directly proportional to pressure
4. Slower in dry air than in moist air
When sound travels from air to water, which parameter does not change?
1. Wavelength
2. Frequency
3. Velocity
4. Temperature
The apparent frequency in Doppler's effect does not depend upon:
1. Speed of listener
2. Distance between the listener and the source
3. Speed of the source
4. Frequency of the source
At what temperature, the speed of sound in the air will become double of its value at $27 ° C$ ?
1. $54 ° C$
2. $627 ° C$
3. $327 ° C$
4. $927 ° C$
The speed of wave in a medium is 760 m/s. If 3600 waves cross the medium in 2 minutes, then its wavelength is:
1. 13.8 m
2. 41.5 m
3. 25.3 m
4. 57.2 m
When a sound travels through air, the air particles:
1. Vibrate along the direction of the wave motion
2. Vibrate but not in any fixed direction
3. Vibrate perpendicular to the direction of the wave motion
4. Do not vibrate
The frequency, which is audible to the human ear is:
1. 50 kHz
2. 20 kHz
3. 15000 kHz
4. 10000 kHz
The velocity of sound in air at a particular temperature is 330 m/s. What will be its value when temperature is doubled and the pressure is halved?
1. 330 m/s
2. 165 m/s
3. $330 \sqrt{2} m / s$
4. $\frac{330}{\sqrt{2}} m / s$
If a sound wave travels with a frequency of $1.25 \times 10^{4} H z$ at 344 m/s, yhe wavelength will be:
1. 27.25 m
2. 275.2 m
3. 0.02752 m
4. 2.752 m
The sound waves are reflected from an obstacle into the same medium from which they were incident. Which of the following changes?
1. Speed
2. Frequency
3. Wavelength
4. None of these
Velocity of sound in the atmosphere of a planet is 500 m/s. The minimum distance between the sources of sound and the obstacle to hear the echo, should be:
1. 17 m
2. 20 m
3. 25 m
4. 50 m
A source producing a sound of frequency 90 Hz is approaching a stationary listener with a speed equal to $\frac{1}{10}$ of the speed of sound. What will be the frequency heard by the listener?
1. 100 Hz
2. 200 Hz
3. 81 Hz
4. None of these
A source producing a sound of frequency 500 Hz is moving towards a listener with a velocity of 30 m/s. The speed of the sound is 330 m/s. What will be the frequency heard by listener?
1. 300 Hz
2. 550 Hz
3. 600 Hz
4. 500 Hz
A source of sound is moving with a velocity of 50 m/s towards a stationary listener. The listener measures the frequency of the source as 1000 Hz. what will be the apparent frequency of the source when it is moving away from the listener after crossing him? (Velocity of sound in the medium is 330 m/s)
1. 848.48 Hz
2. 900 Hz
3. None of these
4. 736.48 Hz
A source and listener are both moving towards each other with a speed $\frac{v}{10}$ where v is the speed of sound. If the frequency of the note emitted by the source is f, what will be the frequency heard by the listener?
1. 1 f
2. 1.22 f
3. 2 f
4. 1.9 f
Which of these is true?
1. Sound waves are longitudinal
2. Sound travel faster in steel than air
3. A sound wave consists of places of higher pressure called compression and place of lower pressure called rarefaction
4. All of these
What is the name of short duration wave?
1. Wavelength
2. Time period
3. Frequency
4. Pulse
Pitch of high frequency sound is?
1. Low
2. High
3. Zero
4. Infinite
Why cant we hear the scream of the bat?
1. Because it scream consist of ultrasonic sound
2. Because it scream consist of infrasonic sound
3. Because they don't emit sound
4. None of these
Sound waves travel with a speed of about 330 m/s. What is the wavelength of sound whose frequency is 550 hertz?
1. 0.6 m
2. 1.6 m
3. 1 m
4. 1.67 m
If a thunder is heard by a man 4 seconds after the lightning is seen, how far is the lightning from the man? (Speed of sound in air = 330 m/s)
1. 82.5 m
2. 1320 m
3. 132 m
4. 1200 m
A sonar device attached to a ship sends ultrasonic waves in the sea. These waves are reflected from the bottom of the sea. If the ultrasonic waves take 4 seconds to travel from the ship to the bottom of the sea and back to the ship, what is the depth of the sea? (Speed of sound in water = 1500 m/s)
1. 6000 m
2. 1500 m
3. 3000 m
4. 2000 m
In SONAR we use:
1. Ultrasonic waves
2. Infrasonic waves
3. Radio waves
4. Audible sound waves
Which kind of sound is produced in an earthquake before the main shock wave begins?
1. Ultrasound
2. Infrasound
3. Audible sound
4. None of these
The ultrasound waves can penetrate into matter to a large extent because they have:
1. Very high speed
2. Very high amplitude
3. Very high wavelength
4. Very high frequency

Acoustics

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