Examples of Longitudinal Waves (Physics Class 11)

📚 Quick Study Guide

• 🌊 Definition: Longitudinal waves are waves in which the displacement of the medium is in the same direction as (or opposite direction to) the direction of propagation of the wave.
• 🔊 Sound Waves: Sound waves are the most common example. They consist of compressions (regions of high pressure and density) and rarefactions (regions of low pressure and density).
• 📏 Wavelength ($\lambda$): The distance between two consecutive compressions or rarefactions.
• 📈 Frequency ($f$): The number of complete oscillations (compressions and rarefactions) passing a point per unit time.
• 💨 Relationship: The speed of a longitudinal wave ($v$) is related to its frequency and wavelength by the equation: $v = f\lambda$.
• 🌡️ Speed of Sound: The speed of sound depends on the medium and temperature. In air at room temperature (approximately 20°C), it is around 343 m/s.
• 📢 Examples: Besides sound, seismic P-waves (primary waves) are also longitudinal.

🧪 Practice Quiz

1. Which of the following is a characteristic of longitudinal waves?
   1. A. Particles move perpendicular to the wave direction.
   2. B. Particles move parallel to the wave direction.
   3. C. Waves require a vacuum to propagate.
   4. D. Waves have crests and troughs.
2. Which of the following is the best example of a longitudinal wave?
   1. A. Light wave
   2. B. Water wave
   3. C. Sound wave
   4. D. Radio wave
3. In a longitudinal wave, what is a region of high pressure called?
   1. A. Trough
   2. B. Crest
   3. C. Rarefaction
   4. D. Compression
4. What does the wavelength of a longitudinal wave represent?
   1. A. The distance between a crest and a trough.
   2. B. The distance between two consecutive compressions.
   3. C. The height of the wave.
   4. D. The speed of the wave.
5. If the frequency of a sound wave is 440 Hz and its wavelength is 0.75 meters, what is its speed?
   1. A. 220 m/s
   2. B. 330 m/s
   3. C. 587 m/s
   4. D. 660 m/s
6. Which of the following mediums generally allows sound to travel the fastest?
   1. A. Vacuum
   2. B. Air
   3. C. Water
   4. D. Steel
7. Seismic P-waves are an example of what type of wave?
   1. A. Transverse wave
   2. B. Longitudinal wave
   3. C. Electromagnetic wave
   4. D. Surface wave