Summary
Sound is a pressure wave created by vibrating objects and requires a medium to travel. It is a longitudinal wave in air, with audible frequencies ranging from 20 Hz to 20,000 Hz for humans.
- Sound Waves — vibrations that travel through a medium as longitudinal waves.
Example: Sound waves in air. - Amplitude — maximum displacement of a particle from its equilibrium position.
Example: Higher amplitude means louder sound. - Frequency — number of waves passing a point per second.
Example: Higher frequency results in a higher pitch. - Compression — region of high particle density in a sound wave.
Example: Air particles are pushed closer together. - Rarefaction — region of low particle density in a sound wave.
Example: Air particles are spread apart. - Echo — reflection of sound waves off surfaces.
Example: Hearing your voice bounce back in a large empty room. - Ultrasound — sound waves with frequencies above 20,000 Hz.
Example: Used in medical imaging to view inside the body.
Exam Tips
Key Definitions to Remember
- Sound waves are longitudinal waves.
- Amplitude relates to loudness; frequency relates to pitch.
- Ultrasound refers to frequencies above 20,000 Hz.
Common Confusions
- Confusing amplitude with frequency when discussing loudness and pitch.
- Misunderstanding that sound cannot travel in a vacuum.
Typical Exam Questions
- What is the speed of sound in air? 330 m/s
- How does frequency affect pitch? Higher frequency results in a higher pitch.
- Describe an experiment to measure the speed of sound in air. Use echoes and measure time for sound to travel to a wall and back.
What Examiners Usually Test
- Understanding of sound wave properties like amplitude and frequency.
- Ability to describe how sound travels through different mediums.
- Knowledge of practical applications of ultrasound.