Physics Chapter: Waves and Periodic Motion

Periodic Motion

• Motion that repeats, from waves, pendulums, or springs.

Waves

• A disturbance transferring energy through matter or space.
• A wave pulse is a single disturbance.
• Two main types: Mechanical and Electromagnetic.
• Mechanical waves need a medium (e.g., water waves, sound waves, waves on a rope).
• Electromagnetic waves do not need a medium (e.g., visible light, radio waves, X-rays).

Mechanical Waves

• Three types: Transverse, Longitudinal, and Surface.
• Transverse waves vibrate perpendicular to the wave's motion.
• Longitudinal waves vibrate parallel to the wave's motion.
• Surface waves have both transverse and longitudinal characteristics.

Measuring and Describing Waves

• Characteristics depend on the wave's production and medium.

• Key characteristics include: speed, amplitude, wavelength, phase, period, and frequency.

• Speed (v): Calculated as distance (d) divided by time (t). Speed depends on the medium for both transverse and longitudinal waves.

• Amplitude (A): Distance from the centerline to a crest or trough, measured in meters (m). Amplitude is directly proportional to energy. Doubling the amplitude increases energy fourfold.

• Wavelength (λ): Distance over which a wave's shape repeats, measured in meters (m). Identical points (e.g., crests, troughs) on adjacent waves are separated by one wavelength. Wavelength and frequency are inversely proportional. (higher wavelength = lower frequency, lower wavelenght = higher frequency).

• Period (T): Time to complete one complete cycle, measured in seconds (s).

• Frequency (f): Number of complete wavelengths per unit time, measured in Hertz (Hz). Frequency and energy are directly proportional (higher frequency = higher energy).

Wave Energy

• Photon energy is inversely proportional to its wavelength.
• Longer wavelengths correspond to lower energy photons.
• Shorter wavelengths correspond to higher energy photons.
• Energy (E) is related to frequency (f) by the equation E = hf, where h is Planck's constant.
• Energy and frequency are directly proportional (higher frequency = higher energy).

Wavelength, Frequency, and Velocity

• Wavelength equals the velocity of a wave divided by its frequency.
• Wavelength and frequency are inversely proportional.
• As wavelength increases, frequency decreases, and vice-versa.