How sound travels | Year 7 Physics (Cambridge) PDF Download

Introduction to Sound

• Sound is produced when an object vibrates, sending waves of energy or vibrations.
• These vibrations travel through a medium in a wave pattern, known as sound waves.
• When sound waves reach our ears, we perceive them as sound.

Transmission of Sound Waves

• Vibration and Air Particles:
  • When an object vibrates, it creates sound waves.
  • These waves cause nearby air particles to vibrate in a chain reaction.
  • The vibrations travel from particle to particle until they reach our ears.
• Mechanism of Hearing:
  • Sound waves reach the eardrum, causing it to vibrate.
  • Vibrations are transmitted through the middle ear to the inner ear (cochlea).
  • In the cochlea, thousands of tiny hair cells convert vibrations into electrical signals.
• Perception of Sound:
  • Electrical signals are sent to the brain via the hearing nerve.
  • The brain interprets these signals, allowing us to recognize and understand sounds.

Factors Affecting Sound

• Amplitude and Loudness:
  • Amplitude refers to the size of vibrations.
  • Stronger vibrations (larger amplitude) produce louder sounds.
  • Weaker vibrations (smaller amplitude) produce quieter sounds.
• Distance and Intensity:
  • Sound intensity decreases with distance from the source.
  • The further away from the source, the quieter the sound becomes.

Propagation Through Different Media

Sound in Different States of Matter:

• Sound can travel through solids, liquids, and gases.
• It requires particles to transmit vibrations.
• In a vacuum (absence of particles), sound cannot propagate.

Conclusion

• Understanding how sound travels helps explain how we hear and perceive sound in our environment.
• Learning about sound waves and their properties enhances our knowledge of the physical world around us.