Sound – Long Answer Questions
Medium Level (Application & Explanation)
Q1. Explain how a guitar and a drum produce sound. Describe the role of vibrations and the surrounding air.
Answer:
- Sound starts when an object vibrates.
- A guitar string vibrates when you pluck it. A drum membrane vibrates when you hit it.
- These vibrations create tiny pressure changes in the surrounding air.
- The pressure changes move outward as sound waves.
- Our ears sense these waves and we hear sound.
- So, without vibrations and a medium like air, there is no sound.
Q2. Why does sound need a medium to travel? Explain using examples from solids, liquids, and gases.
Answer:
- Sound needs a medium to move because it travels by particle-to-particle vibrations.
- In gases like air, particles are far apart, so sound travels slower.
- In liquids like water, particles are closer, so sound travels better.
- In solids, particles are closest, so sound travels the fastest.
- Example: You can hear better underwater than in air.
- Example: Putting your ear on a railway track lets you hear a train earlier.
Q3. What is the relationship between frequency and pitch? Use daily life examples to explain clearly.
Answer:
- Frequency is the number of vibrations per second, measured in Hertz (Hz).
- Pitch is how high or low a sound feels.
- Higher frequency means higher pitch (like a small bird chirping).
- Lower frequency means lower pitch (like a drum beat).
- A tuning fork gives a fixed frequency, so it has a fixed pitch.
- Remember: Pitch depends on frequency, not on how loud the sound is.
Q4. How do amplitude and loudness relate? Explain with examples like whispering and shouting.
Answer:
- Amplitude shows how far particles move from their rest position.
- Greater amplitude means more particle movement and more loudness.
- Smaller amplitude means less movement and a softer sound.
- A whisper has a low amplitude, so it sounds soft.
- A shout has a high amplitude, so it sounds loud.
- At a concert, amplifiers increase amplitude to make music heard by many.
Q5. Compare how sound travels in solids, liquids, and gases. Give reasons and examples.
Answer:
- In solids, particles are tightly packed, so sound travels the fastest.
- In liquids, particles are closer than gases, so sound is faster than in air.
- In gases, particles are far apart, so sound is the slowest.
- Example: You hear a boat engine clearly underwater.
- Example: Sound through a metal rod reaches faster than through air.
- Reason: Closer particles pass on vibrations more quickly.
High Complexity (Analysis & Scenario-Based)
Q6. You make a string telephone using two cups and a string. Explain how it works and what affects the sound quality.
Answer:
- Your voice makes the cup bottom vibrate.
- These vibrations pass into the string as tiny movements.
- The string carries the vibrations to the other cup, which makes sound again.
- The string must be tight; a loose string absorbs vibrations and sound becomes weak.
- A straight string works better than a slack or bent one.
- Touching the string with your hand reduces vibrations and reduces clarity.
Q7. A tuning fork sounds louder when its handle touches a wooden table than when held in the air. Explain why.
Answer:
- The tuning fork vibrates and creates sound in air.
- When it touches the table, its vibrations move into the wood.
- The table has a larger surface area, so it pushes more air.
- More air movement means a larger amplitude and more loudness.
- The table helps transfer and spread the vibrations better.
- So, contact with a large surface makes the sound stronger and clearer.
Q8. Two sounds are heard: a soft but high-pitched bird chirp and a loud, low-pitched drum beat. Analyze how they differ.
Answer:
- The bird chirp has a high frequency, so it has a high pitch.
- It has a small amplitude, so it is soft.
- The drum beat has a low frequency, so it has a low pitch.
- It has a large amplitude, so it is loud.
- Pitch depends on frequency, not on being loud or soft.
- Loudness depends on amplitude, not on being high or low in pitch.
Q9. You are underwater and hear a boat engine clearly, but people shouting from a nearby pier sound faint. Explain this observation.
Answer:
- In water, sound travels faster and often better than in air.
- The engine vibrations move through water, reaching your ears clearly.
- Shouting from the air must cross the air–water boundary.
- Much of that sound is reflected or weakened at the boundary.
- So, voices from above water sound faint underwater.
- The medium change affects how well sound passes through.
Q10. You use rubber bands of different lengths stretched over a box. Predict and explain how the pitch changes when you pluck them.
Answer:
- A shorter rubber band vibrates faster, so it gives a higher pitch.
- A longer rubber band vibrates slower, so it gives a lower pitch.
- When you pluck, the rubber band vibrates and produces a sound wave in air.
- The number of vibrations per second is the frequency.
- Higher frequency means higher pitch; lower frequency means lower pitch.
- This matches what you hear when using different lengths of bands.