Topic 7: One-Page Revision Sheet

Chapter 11: Waves – One Page Revision

1. Wave

A wave is a disturbance that transfers energy from one place to another without transfer of matter.

2. Wave Motion

Propagation of a disturbance through a medium in which particles oscillate about their mean positions.

3. Mechanical Waves

Waves which require a material medium for propagation.

4. Types of Mechanical Waves

Transverse Waves

• Particles vibrate perpendicular to wave direction
• Have crests and troughs
• Example: waves on stretched string

Longitudinal Waves

• Particles vibrate parallel to wave direction
• Have compressions and rarefactions
• Example: sound waves

5. Wave Parameters

• Wavelength (λ): Distance between two successive crests or compressions
• Time Period (T): Time for one complete oscillation
• Frequency (f): Number of oscillations per second

Relations:
f = 1 / T
v = f λ

6. Sound Waves

• Mechanical and longitudinal in nature
• Require a material medium
• Consist of compressions and rarefactions

7. Audible Range

Human audible range: 20 Hz to 20,000 Hz

8. Speed of Sound

• Fastest in solids
• Slower in liquids
• Slowest in gases

9. Factors Affecting Speed of Sound

• Nature of medium
• Density
• Temperature (in gases)
• Humidity (in air)

10. Important Values

• Speed of sound in air at 0°C ≈ 332 m s⁻¹
• Speed of sound in air at room temperature ≈ 343 m s⁻¹

11. Important CET Points

• Difference between transverse and longitudinal waves
• Identification of wave parameters
• Formulas: v = fλ and f = 1/T
• Nature and properties of sound waves
• Factors affecting speed of sound