Fundamental Principles of Wave Physics and Mechanics

Wave Properties and Characteristics

1. Mechanical waves can travel in any type of medium.

2. Refraction occurs when the amplitude of a wave changes as it goes from one medium to another.

Wave Classification and Behavior

• Transverse waves move particles back and forth along the same direction in which the waves travel.
• Mechanical waves can travel either through matter or through empty space.
• The amount of diffraction depends on the size of the obstacle and the wavelength of the wave.

Multiple Choice Questions

Which of the following is NOT a medium through which a mechanical wave can travel?

Answer: b. vacuum

Sound waves do not travel through a(n) _____.

Answer: d. empty space

Sound waves are _____.

Answer: a. longitudinal

Which of the following is transferred during the movement of a wave?

Answer: d. Energy

Which of the following statements about interference is NOT true?

Answer: b. Interference of two waves always results in the formation of a new wave that replaces the original waves.

Which one of the following is NOT an example of a mechanical wave?

Answer: d. radio wave

A place where particles are far apart is a ____.

Answer: c. rarefaction

Visual Analysis of Waves

In the figure shown, point B is called a trough.

In the figure shown, if angle i increases slightly, angle r will increase.

Frequency and Speed Calculations

If the frequency of a sound wave is 7.0 Hz, and the sound wave travels through the air at a speed of 350 m/s, what is the wavelength?

Answer: b. 50 m

Key Concepts in Wave Science

1. The Hz (Hertz) is the unit of measure for the frequency of wavelengths per second.
2. Sound travels faster in solids than in liquids.
3. When two waves interact and their amplitudes cancel out, destructive interference has occurred.
4. Paper that reflects all visible light appears white.
5. Microwaves: Used in cell phones.
6. Amplitude: Related to the energy of a wave.

Short Answer

1. How can light travel from the Sun to Earth through the vacuum of space?

Answer: Light waves are transverse waves. While some transverse waves are mechanical, mechanical waves cannot travel through a vacuum; however, light is an electromagnetic wave that does not require a medium.

Physics Problem Solving

1. A sound wave has a frequency of 627 Hz and a wavelength of 3.25 m. What is the speed of the wave?

   Solution:
   Speed (S) = ?
   Frequency (f) = 627 Hz
   Wavelength (λ) = 3.25 m
   Formula: f × λ = 627 × 3.25 = 2,037.75 m/s

2. A sound wave is traveling at 331 m/s and has a frequency of 126 Hz. What is the wavelength?

   Solution:
   Speed (S) = 331 m/s
   Frequency (f) = 126 Hz
   Wavelength (λ) = ?
   Formula: S / f = 331 / 126 = 2.628 m

3. A sound wave is traveling at 3,810 m/s and has a wavelength of 8 m. What is the frequency of the wave?

   Solution:
   Speed (S) = 3,810 m/s
   Wavelength (λ) = 8 m
   Frequency (f) = ?
   Formula: S / λ = 3,810 / 8 = 476.25 Hz