Physics Waves and Light Refraction

Physics Waves

• A wave is a disturbance or vibration that transmits energy, not matter.
• Transverse wave: Particles move perpendicular to the wave motion.
• Longitudinal wave: Particles move parallel to the wave motion.
• Surface wave: Combination of transverse and longitudinal waves.
• Amplitude: Maximum displacement from crest to trough.

Refraction

• Refraction: Bending of light as it changes medium.
• Optical density: Measure of how difficult it is for light to travel in a substance.
• Angle of incidence: Angle between incident ray and normal.
• Angle of refraction: Angle between refracted ray and normal.
• Light refracts away from the normal when passing from a denser to less dense medium.
• Light slows down and bends towards the normal when passing from a less dense to a denser medium.
• Critical angle: Angle of incidence that results in an angle of refraction of 90 degrees. This results in total internal reflection.

Reflection and Transmission

• If the medium remains constant, waves travel at a uniform speed.
• Sound waves travel faster in solids as particles are closer together.
• Waves act differently when passing through different mediums and temperatures.
• Reflected pulses from fixed ends invert.
• Reflected pulses from free ends do not invert.

Interference

• Superposition principle: Sum of amplitudes of individual waves.
• Constructive interference: Waves with the same frequency and phase combine, increasing amplitude.
• Destructive interference: Waves with the same frequency but opposite phases combine, cancelling out or reducing amplitude.
• Standing waves are formed by constructive and destructive interference of waves traveling in opposite directions.
• Nodes are areas of complete destructive interference with zero amplitude.
• Antinodes are areas of complete constructive interference with maximum amplitude.
• Waves reflecting from fixed boundaries invert.

Diffraction

• Diffraction occurs when the wavelength of a wave is comparable to the size of an obstacle or aperture.
• Diffraction causes bending of waves around obstacles.
• Smaller apertures lead to more pronounced diffraction effects.

Standing Waves

• Standing waves form when two waves of equal amplitude, frequency, and wavelength travel in opposite directions.
• Standing waves on strings with two fixed ends have frequencies f = nv/2L.
• Standing waves in pipes with one fixed and one open end have frequencies f = nv/4L.

Sound Waves

• Sound waves are longitudinal waves of pressure, stimulating ear drums.
• Sound speed depends on the medium's density: denser medium = faster sound.
• Frequency determines pitch, and amplitude determines volume.
• Beats are periodic fluctuations of sound intensity when waves with similar frequencies interfere; beat frequency is |f₂ – f₁|.

Doppler Effect

• Doppler effect: Apparent change in frequency of a wave when the source or observer is moving relative to the medium.
• Moving source toward an observer increases the apparent frequency.
• Moving source away from an observer decreases the apparent frequency.