IB Physics Topic C - Wave Behaviour Key Definitions

Amplitude is the maximum displacement of an oscillating object from its equilibrium position.

Angular frequency $\omega$ is the rate of change of phase of an oscillation, equal to $2\pi f$ and measured in radians per second (rad s$^{-1}$).

Antinodes are points on a standing wave where the displacement reaches its maximum value.

Blueshift is the decrease in the observed wavelength (and increase in frequency) of electromagnetic radiation from a source moving toward the observer. The spectrum shifts toward the blue (higher-frequency) end.

A compression is a region in a longitudinal wave where the particles of the medium are close together, resulting in a high-pressure area. In sound waves, compressions correspond to regions of increased air density and pressure.

A crest is the highest point of a wave, where the displacement of the medium is at its maximum positive value relative to the equilibrium position. In a transverse wave, crests correspond to peaks in the wave motion.

The angle of incidence in the higher-index medium for which the angle of refraction is 90° (the refracted ray travels along the boundary).

Critical damping occurs when a system returns to its equilibrium position in the shortest possible time without oscillating.

Damping is the gradual reduction in the amplitude of an oscillating system due to resistive forces, such as friction or air resistance, that dissipate energy from the system over time.

Diffraction is the spreading of waves as they pass through an aperture or around an obstacle.

The Doppler effect is the change in the observed frequency of a wave when there is relative motion between the source and the observer

Electromagnetic waves are composed of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of wave propagation.

Frequency is the number of complete oscillations per unit time, measured in hertz (Hz).

Fringe spacing refers to the distance between adjacent bright or dark fringes in an interference pattern, typically observed in double-slit experiments or diffraction patterns.

The fundamental frequency is the lowest frequency at which a system can sustain a standing wave, corresponding to the first harmonic. All higher harmonics are integer multiples of this frequency.

A harmonic is a standing wave pattern that fits the boundary conditions of a system. The first harmonic (fundamental) is the lowest frequency; higher harmonics have frequencies that are integer multiples of it.

Heavy damping is defined as a type of damping where the body attains its equilibrium gradually without any oscillation.

Light damping is when the amplitude of each oscillation is fractionally less than the previous one

A mass-spring system consists of a mass attached to a spring. When displaced from equilibrium and released, it undergoes SHM with period $T = 2\pi\sqrt{m/k}$, where $m$ is the mass and $k$ is the spring constant.

Mechanical waves are waves that require a medium (such as air, water, or a solid) to propagate.

A natural frequency is a frequency at which the system naturally oscillates when not disturbed by external forces.

Nodes are points on a standing wave where the displacement is always zero.

Path difference is the difference in distance traveled by the waves from their sources to the point of overlap.

The period ($T$) is the time taken for one complete revolution.