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- Sound is generated by the vibration of various objects.
- Sound propagates as a longitudinal wave through a material medium.
- Sound moves through a medium in a series of compressions and rarefactions.
- In sound transmission, it is the sound energy that moves, not the medium’s particles.
- Loudness is the ear’s response to the intensity of sound.
- Sound intensity is the amount of sound energy passing through a unit area each second.
- The human ear can detect sound frequencies in the range of 20 Hz to 20 kHz.
- Sounds with frequencies below the audible range are called "infrasonic," while those above are termed "ultrasonic.
- Ultrasound is used in various medical and industrial fields.
- A complete oscillation occurs when the density changes from a maximum to a minimum and back to maximum.
- The wavelength (λ) is the distance between two consecutive compressions or rarefactions.
- The time taken for one full oscillation of density or pressure in the medium is called the time period (T).
- Frequency (ν) refers to the number of complete oscillations per unit of time, calculated as ν = 1/T.
- The speed (v), frequency (ν), and wavelength (λ) of sound are connected by the formula v = λν.
- The speed of sound is influenced mainly by the type of medium and its temperature.
- According to the law of reflection, the angle of incidence and the angle of reflection of sound are equal, and both are on the same plane as the normal.
- To distinguish an echo, the time gap between the original and reflected sound must be at least 0.1 second.
- Reverberation occurs when sound persists in a space due to repeated reflections, like in an auditorium.
- Loudness is a physiological response that reflects the sound’s intensity.
- Sound intensity refers to the amount of sound energy passing through a unit area per second.
- Human hearing typically detects frequencies between 20 Hz and 20 kHz.
- "Infrasonic" sounds have frequencies below the human hearing range, while "ultrasonic" sounds have frequencies above it.
- Ultrasound has a wide range of applications in medicine and industry.
- Characteristics like pitch, loudness, and quality of sound are determined by the properties of the corresponding sound wave.
1. What is sound?
(a) A form of mechanical energy
(b) A form of potential energy
(c) A form of nuclear energy
(d) A form of chemical energy
Explanation: Sound is a form of mechanical energy that requires a medium for propagation
2. How is sound produced?
(a) By vibrating objects
(b) By still objects
(c) By motionless air
(d) By light waves
Explanation: Sound is produced due to the vibration of objects, which causes the surrounding medium to vibrate
3. In which medium does sound travel the fastest?
(a) Air
(b) Water
(c) Iron
(d) Vacuum
Explanation: Sound travels fastest in solids like iron because the molecules are tightly packed, facilitating quicker transmission
4. What is the audible range of sound for humans?
(a) 0 to 100 Hz
(b) 20 Hz to 20 kHz
(c) 100 Hz to 1 MHz
(d) Above 1 MHz
Explanation: Humans can hear sounds in the range of 20 Hz to 20,000 Hz
5. Which of the following waves are sound waves?
(a) Longitudinal waves
(b) Transverse waves
(c) Electromagnetic waves
(d) Gravitational waves
Explanation: Sound waves are longitudinal because the particles of the medium move parallel to the direction of wave propagation
6. What is the unit of frequency?
(a) Meter
(b) Second
(c) Hertz
(d) Joule
Explanation: The unit of frequency is Hertz (Hz), which measures the number of oscillations per second
7. What property of sound determines its pitch?
(a) Amplitude
(b) Frequency
(c) Speed
(d) Wavelength
Explanation: Pitch is determined by the frequency of the sound wave. Higher frequency results in higher pitch
8. What is the effect of amplitude on sound?
(a) It affects the pitch
(b) It affects the loudness
(c) It affects the speed
(d) It affects the frequency
Explanation: The amplitude of sound determines its loudness. Larger amplitude means louder sound
9. Which phenomenon explains why we hear echoes?
(a) Reflection of sound
(b) Refraction of sound
(c) Diffraction of sound
(d) Absorption of sound
Explanation: Echoes are heard due to the reflection of sound waves from a surface back to the listener
10. What is the time interval required to hear a distinct echo?
(a) 001 s
(b) 01 s
(c) 1 s
(d) 10 s
Explanation: For a distinct echo to be heard, the time interval between the original sound and its echo must be at least 01 seconds
11. Why is sound considered a mechanical wave?
(a) It does not require a medium to travel
(b) It requires a medium for propagation
(c) It travels through space
(d) It is a type of electromagnetic wave
Explanation: Sound is a mechanical wave because it requires a material medium (solid, liquid, or gas) for its transmission
12. What is the wavelength of sound?
(a) The time taken for one oscillation
(b) The distance between two consecutive compressions or rarefactions
(c) The distance between the source and the observer
(d) The distance traveled by sound in one second
Explanation: Wavelength is the distance between two consecutive compressions or rarefactions in a sound wave
13. Which sound property determines loudness?
(a) Frequency
(b) Amplitude
(c) Wavelength
(d) Speed
Explanation: Loudness is directly proportional to the amplitude of the sound wave
14. Which is true about the speed of sound in different media?
(a) It is the same in all media
(b) It is highest in gases
(c) It is highest in solids
(d) It is highest in liquids
Explanation: Sound travels fastest in solids, followed by liquids and then gases
15. What is reverberation?
(a) The repeated reflection of sound in an enclosed space
(b) The refraction of sound waves
(c) The absorption of sound waves
(d) The diffraction of sound waves
Explanation: Reverberation occurs when sound waves are reflected multiple times in a confined space
16. Which device uses ultrasound to examine internal organs?
(a) Stethoscope
(b) Ultrasound scanner
(c) X-ray machine
(d) Thermometer
Explanation: Ultrasound scanners use high-frequency sound waves to create images of internal body organs
17. What is the SI unit of wavelength?
(a) Meter
(b) Second
(c) Hertz
(d) Newton
Explanation: Wavelength is measured in meters (m) in the SI system
18. Why can't sound travel in a vacuum?
(a) It is too slow
(b) There are no particles to transmit the vibrations
(c) It is absorbed by the vacuum
(d) It gets scattered
Explanation: Sound requires a medium (particles) to propagate, and in a vacuum, there are no particles to transmit the sound vibrations
19. What happens to the pitch of sound as the frequency increases?
(a) It decreases
(b) It increases
(c) It stays the same
(d) It fluctuates
Explanation: Pitch is directly related to frequency. As the frequency increases, the pitch becomes higher
20. Which characteristic of sound is affected by temperature?
(a) Frequency
(b) Amplitude
(c) Speed
(d) Pitch
Explanation: The speed of sound increases with an increase in the temperature of the medium
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