Imp Questions For All Chapters – General Science Class 7
Sound : Production of Sound
Short Questions
1. What is sound?
→ Sound is a form of energy produced by vibrations.
2. How is sound produced?
→ Sound is produced when an object vibrates and creates waves in the air.
3. What is required for sound to travel?
→ Sound needs a medium (solid, liquid, or gas) to travel.
4. Why can’t sound travel in space?
→ Space has no air or medium to carry sound waves.
5. What is an oscillator?
→ An oscillator is an object that moves back and forth repeatedly (e.g., a pendulum).
6. What is the time period of an oscillation?
→ The time taken to complete one full oscillation is called the time period.
7. What is the unit of frequency?
→ Frequency is measured in Hertz (Hz).
8. What is amplitude?
→ Amplitude is the maximum distance a vibrating object moves from its resting position.
9. How does amplitude affect sound?
→ A higher amplitude produces a louder sound, while a lower amplitude produces a softer sound.
10. What is pitch?
→ Pitch is how high or low a sound is, depending on its frequency.
11. What is the human hearing range?
→ Humans can hear sounds between 20 Hz and 20,000 Hz.
12. What are infrasonic sounds?
→ Sounds with a frequency below 20 Hz that humans cannot hear.
13. What are ultrasonic sounds?
→ Sounds with a frequency above 20,000 Hz, used by bats and dolphins.
14. Why do elephants use infrasonic sounds?
→ Elephants use infrasonic sounds to communicate over long distances.
15. What is SONAR used for?
→ SONAR (Sound Navigation And Ranging) is used to detect objects underwater, like submarines and fish.
Long Questions
1. How does sound travel from one place to another?
→ Sound travels in the form of waves through a medium like air, water, or solids. The waves carry vibrations from the source to our ears.
2. Why do tabla and sitar produce different sounds?
→ The materials, shape, and vibration patterns of tabla and sitar are different, which causes them to produce different sounds with different frequencies.
3. What is the relationship between frequency and pitch?
→ Higher frequency means higher pitch (shrill sound), and lower frequency means lower pitch (deep sound). For example, a mosquito’s buzz is high-pitched.
4. How do bats use ultrasonic sound?
→ Bats produce ultrasonic waves and listen to their echoes to navigate and catch prey in the dark.
5. Why do we hear the buzzing sound of a mosquito but not our hands moving?
→ A mosquito’s wings vibrate at a high frequency (above 200 Hz), while our hands move too slowly to produce a sound we can hear.
6. How does the length of a pendulum affect its frequency?
→ A longer pendulum swings slowly with a low frequency, while a shorter pendulum swings faster with a higher frequency.
7. What happens if you increase the tension in a stretched string?
→ Increasing the tension makes the string vibrate faster, producing a higher-pitched sound.
8. How does SONAR work?
→ SONAR sends ultrasonic waves into water, and when the waves bounce back from an object, the system detects its location and distance.
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