Infrasonic, Ultrasonic and Audio waves

Q.

Cite an experiment to show that sound needs a material medium for its propagation.

Q. Which of the following is true about sound?

1. Sound is a wave.
2. Sound can travel in a vacuum.
3. Sound is a form of energy.
4. None of these

Q. SONAR is used to measure___

1. The depth of a sea
2. Height of a mountain
3. The height of a hill
4. The height of a plateau

Q.

For a screw gauge, how are the pitch and least count related?

Q.

Generally, women have a shriller voice than men, this is because they produce a sound which has higher:

1. Frequency

2. Time period

3. Intensity

4. Amplitude

Q.

How do some animals possibly know about the earthquakes before human beings? Do bats use the same ability to hunt their prey?
[3 MARKS]

Q.

A rescue plane flies horizontally at a constant speed searching for a disabled boat. When the plane is directly above the boat, the boats crew blows a loud horn. By the time the planes sound detector receives the horns sound, the plane has travelled a distance equal to one half of its altitude above the ocean. If it takes sound$2s$ to reach the plane, then determine (a) speed of plane, (b) its altitude. Speed of sound as $t=2s$$340m/s$.

Q. A SONAR device uses ultrasound to find out the average depth of the Caspian Sea. The sound of wavelength $10\text{mm}$ and frequency $150\text{kHz}$, reflects back to the device in about $1.4\text{s}$. What is the depth of the sea in $\text{km}$?

1. 1.05

Q.

Will the sound be audible, if the string is set into vibration on the surface of the moon?
Give the reason for your answer.

Q. Which of the following animals can hear ultrasounds?
a) Dogs, b) Whales, c) Bats, d) Dolphins

1. b, c and d
2. a, b and d
3. a and c
4. All of these

Q.

There are two boxes A & B. Cell phones are kept in both the boxes, all air is sucked from box A and then closed by a device. While box B is simply closed by a device without sucking air from it. A call is made simultaneously on both the phones, but the sound comes only from box B. This is because

Statement 1: In box B there are air particles to vibrate but in box A there is a vacuum

Statement 2: Sound needs a medium for propagation

Q.

A sonar signal sent down from ship, is reflected from the ocean floor and detected by a hydrophone 0.6 s later. Calculate the depth of the ocean.

Take the speed of sound in sea water as $1500m{s}^{-1}$

Q.

Will the sound be audible if string is set into vibration on the surface of the moon. Give reason for your answer.

Q.

Which of the following correctly supports the fact that bats can hunt at night?

1. They have an excellent eyesight.

2. They can smell their prey.

3. They use ultrasonic waves to detect the position of the prey.

4. They have excellent camouflage capability.

Q.

Write some applications of ultrasonic sound in surgical applications?

Q. What can be the reason behind elderly people reading the newspaper keeping the paper at a distance more than the usual?

1. Myopia
2. Astigmatism
3. Cataract
4. Presbyopia

Q. Sort the following parts of a human ear, in the correct order of the propagation of sound.

1. Auditory nerve
2. Ear canal
3. Ear drum
4. Cochlea
5. Pinna

Q. The frequency range of audible sound is 20 Hz to 20 kHz.

1. True
2. False

Q. Why we can hear the sound produced by bees but we cant hear the sound of vibrations of pendulum?

1. Sound of bees are in infrasonic range while sound of vibrations of pendulum are in ultrasonic range
2. Sound of vibrations of pendulum is in audible rays
3. None is true
4. Sound of bees are in audible range

Q. Identify the part of the human ear that converts sound into electrical impulses.

1. 
2. 
3. 
4. 

Q. A vibrating body produces sound. However no sound is heard when a simple pendulum oscillates in air. Why?

1. Frequency of vibration of pendulum is more than 20 Hz
2. Frequency of vibration of pendulum is very high.
3. Frequency of vibration of pendulum is less than 20 Hz
4. Frequency of vibration of pendulum is exactly equal to 20 Hz.

Q.

List some of the methods used to determine very long distances.

Q. A sound waves having certain frequency travels with a speed of 336 m/s and wavelength 3 cm. Calculate the frequency. Will it be audible?

1. $1120Hz,Yes$
2. $11200Hz,Yes$
3. $11200Hz,No$
4. $1120Hz,No$

Q. Frequency range of audible sound for humans is $20Hz$ and $20000Hz$. Find the corresponding range of time period for these audible sound.

1. $0.05sto5\times {10}^{-5}$ s
2. $0.5sto5\times {10}^{-5}$ s
3. $5sto5\times {10}^{-5}$ s
4. $0.05sto2.5\times {10}^{-5}$ s

Q. What are the uses of ultrasonic sounds?

1. To track medical problems
2. To study molecular structures
3. For navigational studies and by animals to locate prey and obstacles
4. All of the above

Q.

Choose the correct option:

$$\begin{array}{cccc}1.& Tone& i.& frequenciesthatareintegralmultipleoffundamentalfrequency.\\ 2.& Note& ii.& soundofsinglefrequency.\\ 3.& Overtone& iii.& soundofmultiplefrequencies.\\ 4.& Harmonic& iv.& higherfrequenciesotherthanfundamentalfrequency.\end{array}$$

1. 1 - ii, 2 - iii, 3 - iv, 4 - i.

2. 1 - iii, 2 - ii, 3 - iv, 4 - i

3. 1 - ii, 2 - iii, 3 - i, 4 - iv

4. 1 - ii, 2 - iv, 3 - iii, 4 - i

Q. How are bats able to fly in the dark?

1. They produce infrasonic waves.
2. They can hear ultrasonic sounds.
3. They produce infrared waves.
4. They can hear infrared waves.

Q.

input audio signal is given below. which of the following can be amplified audio signal

1. 1
   

2. 2
   
   

3. 3
   
   

4. 4
   

Q. Four whistles W, X, Y, Z when blown produce pure notes with frequencies 0.1 kHz, 1 kHz, 10 kHz, 100 kHz respectively. Which of the above whistles produce higher and lower pitch. Are the sounds of higher and lower pitch audible to humans?

Q.

If the frequency of sound lies between 20 $Hz$ and 20000$Hz$ , it is known as __________ sound.