Waves

Waves: transfer energy without transferring matter. Transverse waves: vibrations perpendicular to direction (light, water, EM waves). Longitudinal waves: vibrations parallel to direction (sound). Wave properties: wavelength (λ) = distance between peaks, frequency (f) = waves per second (Hz), amplitude = height of wave (energy), period = time for one wave. Wave equation: v = fλ (speed = frequency × wavelength). Reflection: wave bounces off surface, angle of incidence = angle of reflection. Refraction: wave changes speed/direction when entering different medium. Diffraction: wave spreads through gap or around obstacle. Sound: longitudinal wave, needs medium (not in vacuum), travels faster in solids than gases. Speed in air ≈ 330 m/s. Pitch: determined by frequency (high frequency = high pitch). Loudness: determined by amplitude (large amplitude = loud). Echo: reflected sound. Ultrasound: frequency above 20,000 Hz, used in medical scans and sonar. Human hearing: 20 Hz to 20,000 Hz. Electromagnetic spectrum: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma. All travel at speed of light in vacuum (3 × 10⁸ m/s). All transverse. Different wavelengths and frequencies.