Question 1

Sound is a form of energy produced when an object _____, causing the surrounding medium to vibrate and transmit sound waves.

Accepted Answer

vibrates — Sound is produced by vibrations of an object. These vibrations cause the particles of the surrounding medium to vibrate, transmitting sound energy as waves.

Question 2

Which of the following media does sound travel fastest through?

Accepted Answer

Steel — Sound travels fastest in solids like steel because particles are closely packed, allowing vibrations to transmit quickly. It travels slower in liquids like water and slowest in gases like air. Sound cannot travel through a vacuum as there are no particles to transmit vibrations.

Question 3

The pitch of a sound is determined by which characteristic of the sound wave?

Accepted Answer

Frequency — Pitch depends on the frequency of the sound wave. Higher frequency results in a higher pitch, while lower frequency produces a lower pitch.

Question 4

Which of the following terms refers to sounds with frequencies above 20,000 Hz?

Accepted Answer

Ultrasound — Ultrasound refers to sound waves with frequencies above 20,000 Hz, which are beyond the range of human hearing.

Question 5

Sound waves are classified as which type of waves?

Accepted Answer

Longitudinal waves — Sound waves are longitudinal waves where particles vibrate parallel to the direction of wave propagation, creating compressions and rarefactions.

Question 6

Assertion (A): Sound cannot travel through a vacuum.
Reason (R): There are no particles in a vacuum to transmit vibrations.

A) Both A and R are true and R is the correct explanation of A
B) Both A and R are true but R is NOT the correct explanation of A
C) A is true but R is false
D) A is false but R is true

Accepted Answer

A — Assertion is true because sound requires a medium with particles to travel. Reason is true because a vacuum lacks particles to transmit vibrations. The reason correctly explains the assertion.

Question 7

Explain how sound is produced and travels from a source to a listener.

Accepted Answer

Sound is produced when an object vibrates. These vibrations cause the particles of the surrounding medium to vibrate as well. The vibrations travel through the medium in the form of longitudinal waves, carrying sound energy from the source to the listener. For example, when a guitar string is plucked, it vibrates and produces sound. — Sound production involves vibration of an object, which causes the medium's particles to vibrate and transmit sound waves to the listener.

Question 8

Describe the difference between pitch and loudness of sound with examples.

Accepted Answer

Pitch is the characteristic of sound determined by frequency; higher frequency means higher pitch. Loudness depends on the amplitude of the sound wave; greater amplitude means louder sound. For example, a whistle has a high pitch but low loudness, while a drum has a low pitch but high loudness. — Pitch relates to frequency, loudness to amplitude. Examples help distinguish these characteristics.

Question 9

What is an echo, and under what condition can it be heard distinctly by a listener?

Accepted Answer

An echo is the reflection of sound waves from a surface back to the listener. It can be heard distinctly if the reflected sound reaches the listener after at least 0.1 seconds from the original sound, meaning the reflecting surface should be at least 17 meters away. — Echo requires reflection and a minimum time delay to be heard separately from the original sound.

Question 10

How do bats use the reflection of sound for navigation?

Accepted Answer

Bats emit high-frequency sound waves that reflect off objects in their surroundings. By listening to the echoes, bats can determine the location and distance of obstacles and prey, enabling navigation and hunting in the dark. — Bats use echolocation, a practical application of sound reflection, to navigate and locate prey.

Question 11

A person claps near a large wall and hears the echo after 0.2 seconds. Calculate the distance of the wall from the person. (Speed of sound = 340 m/s)

Accepted Answer

34 meters — Given: Time for echo = 0.2 s, speed of sound = 340 m/s
Find: Distance to the wall
Formula: Distance = (Speed × Time) / 2
Solution: Step 1: Distance = (340 × 0.2) / 2
Step 2: Distance = 68 / 2
Step 3: Distance = 34 meters
Answer: The wall is 34 meters away.
Note: The time is for the sound to travel to the wall and back, so divide by 2.

Question 12

What is noise pollution, and list two harmful effects it can have on human health.

Accepted Answer

Noise pollution is unwanted or harmful sound that negatively affects human health. Two harmful effects are hearing loss and increased stress levels. — Noise pollution causes health issues such as hearing impairment and stress, affecting well-being.

Question 13

Which of the following is NOT a method to reduce noise pollution?

Accepted Answer

Increasing loudspeaker volume — Increasing loudspeaker volume increases noise pollution. Using earplugs, planting trees, and noise barriers help reduce noise pollution.

Question 14

Explain the difference between infrasound and ultrasound with examples of animals that can hear these sounds.

Accepted Answer

Infrasound refers to sound waves with frequencies below 20 Hz; elephants can hear infrasound. Ultrasound refers to sound waves with frequencies above 20,000 Hz; bats and dolphins can hear ultrasound. — Infrasound and ultrasound are sound waves outside the human hearing range, detected by specific animals for communication or navigation.

Question 15

How does the amplitude of a sound wave affect its loudness? Provide an example.

Accepted Answer

Loudness of sound increases with the amplitude of the sound wave; greater amplitude means louder sound. For example, hitting a drum harder produces a louder sound due to larger amplitude vibrations. — Amplitude relates to energy in the wave, affecting loudness perceived by the ear.

Sound

Sound — Study Notes

Introduction

Production of Sound

Propagation of Sound

Practice Questions — Sound

All 13 Chapters in Science