1.
The echo-receiver of a sonar attached to a ship, receives the echo from the bottom of sea 4 seconds after the ultrasonic waves were sent into the sea. If the speed of sound in water is 1500 m/s, then what is the depth of the sea?
Correct Answer
B. 3000 m
Explanation
The depth of the sea can be calculated using the formula: Depth = Speed of Sound x Time / 2. In this case, the speed of sound is given as 1500 m/s and the time is 4 seconds. Plugging these values into the formula, we get: Depth = 1500 m/s x 4 s / 2 = 3000 m. Therefore, the depth of the sea is 3000 m.
2.
Before the main shock waves, the earthquake produces the characteristic sound waves which some animals like rhinoceros can hear. Can you guess the kind of sound waves produced here?
Correct Answer
A. Infrasonic sounds
Explanation
Infrasonic sounds are low-frequency sound waves that have a frequency below the range of human hearing. These sound waves are produced by the earthquake before the main shock waves occur. Animals like rhinoceros, which have sensitive hearing, are able to detect these infrasonic sounds. Ultrasonic sounds, on the other hand, have a frequency above the range of human hearing. Audible sounds are within the range of human hearing. Therefore, the correct answer is infrasonic sounds, as they are the type of sound waves produced by the earthquake that can be heard by animals like rhinoceros.
3.
Given below is the diagram of human ear. Choose the correct labeling of the parts A, B and C.
Correct Answer
C. A-ear canal, B-Eustachian tube, C-auditory nerve
4.
On increasing the temperature, the speed of sound in air:
Correct Answer
A. Increases
Explanation
As the temperature increases, the molecules in the air gain more kinetic energy and move faster. This increased molecular motion leads to an increase in the speed of sound in air. Therefore, on increasing the temperature, the speed of sound in air increases.
5.
Loudness measures the sound energy reaching the ear per second and depends on the amplitude of the sound wave. What is the unit used to measure the loudness of sound?
Correct Answer
B. Decibel
Explanation
Loudness is a measure of the sound energy reaching the ear per second, and it is dependent on the amplitude of the sound wave. The unit used to measure loudness is the decibel (dB). The decibel scale is logarithmic and is used to quantify the intensity or level of sound. It provides a more accurate representation of the wide range of sound intensities that can be perceived by the human ear. Therefore, the decibel is the appropriate unit for measuring loudness.
6.
We can easily distinguish between the sounds of the different singers even without having seen them. This is all due the different quality or timber of their sounds. On what factor does the quality of sound depend?
Correct Answer
B. Waveform
Explanation
The quality of sound depends on the waveform. The waveform refers to the shape of the sound wave, which determines the characteristics of the sound such as its timbre or tone color. Different singers have different waveforms, which result in variations in their sound quality. Therefore, even without visual cues, we can distinguish between singers based on the unique waveform of their sounds.
7.
Before playing the orchestra in a musical concert, a sitarist tries to adjust the tension and pluck the string suitably. By doing so, he is adjusting
a) The amplitude of the sound
b) Frequency of the sitar string with the frequency of other musical instruments
c) Intensity of sound
d) Loudness of sound
Choose the correct option:
Correct Answer
B. Only b
Explanation
The sitarist adjusts the tension and plucks the string suitably in order to match the frequency of the sitar string with the frequency of other musical instruments. This ensures that the sitar is in tune with the rest of the orchestra, creating a harmonious sound.
8.
The bats can fly in the darkness of night without colliding with the other objects by emitting special sounds while flying. Which characteristic sound is used by the bats to navigate?
Correct Answer
A. Ultrasound
Explanation
Bats use ultrasound to navigate in the darkness of night without colliding with objects. Ultrasound refers to high-frequency sound waves that are above the range of human hearing. Bats emit these high-frequency sounds, which bounce off objects in their surroundings. By listening to the echoes of these sounds, bats can determine the location, distance, and shape of objects around them. This enables them to navigate and avoid collisions while flying in the dark.
9.
The sound travels from particle to particle in the form of vibrations and has different speeds in different mediums.
The maximum speed of vibrations which produce audible sound will be in:
Correct Answer
B. Ground glass
Explanation
Sound travels faster in denser mediums because the particles are closer together, allowing the vibrations to propagate more quickly. Ground glass is denser than sea water, human blood, and dry air, so it would have a higher maximum speed of vibrations. Therefore, ground glass would be the medium in which sound would travel the fastest.
10.
Which of the following can produce longitudinal as well as transverse waves under different conditions?
Correct Answer
B. Slinky
Explanation
A slinky can produce both longitudinal and transverse waves under different conditions. When the slinky is stretched or compressed along its length, it produces longitudinal waves, where the particles of the slinky vibrate parallel to the direction of the wave. On the other hand, when the slinky is shaken side to side, it produces transverse waves, where the particles of the slinky vibrate perpendicular to the direction of the wave. Therefore, a slinky is capable of producing both types of waves depending on how it is manipulated.
11.
If the speed of a wave is 380 m/s and its frequency is 1900 Hz, then the wavelength of the wave will be:
Correct Answer
B. 0.2 m
Explanation
The speed of a wave is determined by the product of its frequency and wavelength. The formula is v = f * λ, where v is the speed, f is the frequency, and λ is the wavelength. Rearranging the formula to solve for wavelength, we get λ = v / f. Plugging in the given values, we have λ = 380 m/s / 1900 Hz = 0.2 m. Therefore, the wavelength of the wave is 0.2 m.
12.
You must have seen the doctor checking the sounds produced in the chest or heartbeat of a patient using a medical instrument called Stethoscope. On what principle does this Stethoscope work?
Correct Answer
B. Multiple reflections
Explanation
The correct answer is multiple reflections. A stethoscope works on the principle of multiple reflections. When the doctor places the chest piece of the stethoscope on the patient's body, sound waves produced by the body organs travel through the tubing to the doctor's ears. The sound waves undergo multiple reflections within the tubing, which helps to amplify and transmit the sound to the doctor's ears. This allows the doctor to listen to the sounds produced in the chest or heartbeat of the patient and make a diagnosis.
13.
We can distinguish between a man’s voice and a woman’s voice of the same loudness even without seeing them. This is due to a characteristic of sound which measures the shrillness of sounds. Can you choose the correct unit of the quantity on which this characteristic of sound depends?
Correct Answer
A. Hertz
Explanation
The correct unit of the quantity on which the characteristic of sound depends is hertz. Hertz is the unit of frequency, which is the number of cycles or vibrations per second. In this case, the characteristic of sound that allows us to distinguish between a man's voice and a woman's voice is the pitch, which is determined by the frequency of the sound waves. A higher frequency (measured in hertz) corresponds to a higher pitch or shrillness, while a lower frequency corresponds to a lower pitch.
14.
The sound can travel in air when:
Correct Answer
C. Disturbance move
Explanation
Sound is a form of energy that travels through a medium by creating a disturbance. In the case of air, sound waves are created when particles of air are disturbed by a vibrating source, such as a speaker or vocal cords. These disturbances then propagate through the air, causing neighboring particles to vibrate and transfer the energy. Therefore, the correct answer is that sound can travel when disturbances move through the medium.
15.
A key of the mechanical piano is first struck gently and then struck again but much harder this time. What kind of change in sound will you observe in the second case:
Correct Answer
C. Sound will be louder but the pitch will be lower
Explanation
When the key of a mechanical piano is struck harder, the sound produced will be louder due to the increased force applied to the strings. However, the pitch will be lower because the increased force causes the strings to vibrate with a slower frequency, resulting in a lower pitch.