HL IB Physics - Wave Phenomena

Vocabulary-style flashcards covering wave phenomena including wavefronts, reflection, refraction, diffraction, superposition, and interference as outlined in the HL IB Physics lecture notes.

Surface wave

A wave that propagates in two dimensions and has circular wavefronts, such as on the surface of water.

Spherical wave

A wave that propagates in three dimensions and has spherical wavefronts, such as sound or light.

Wavefronts

Lines joining all the points that oscillate in phase and are perpendicular to the direction of motion and energy transfer.

Rays

Lines showing the direction of motion and energy transfer of the wave, perpendicular to the wavefront.

Medium

In optics, the name given to a transparent material; plural is media.

Reflection

When a wave hits a boundary between two media and does not pass through, but instead bounces back to the original medium.

Law of reflection

States that the angle of incidence $i$ equals the angle of reflection $r$.

Refraction

The change in direction of a wave when it passes through a boundary between mediums of different density, caused by a change in wave speed.

Transmission

The general term for a wave appearing on the opposite side of a boundary after passing through a substance.

Diffraction

The spreading out of waves after they pass through a narrow gap (aperture) or around an obstruction (barrier).

Refractive Index ($n$)

A dimensionless quantity that indicates how optically dense a material is, calculated by $n = \frac{c}{v}$ where $c = 3.00 \times 10^8 \text{ m s}^{-1}$.

Snell's Law

The relationship used to describe light at a boundary: $n_1 \times \text{sin}(\theta_1) = n_2 \times \text{sin}(\theta_2)$, where $\theta_1$ is the angle of incidence and $\theta_2$ is the angle of refraction.

Critical Angle ($\theta_c$)

The specific angle of incidence where the angle of refraction is exactly $90^\text{o}$, calculated using $\text{sin}(\theta_c) = \frac{n_2}{n_1}$.

Total Internal Reflection (TIR)

Occurs when the angle of incidence within a denser medium is greater than the critical angle ($i > \theta_c$) and the incident refractive index $n_1$ is greater than $n_2$.

Principle of superposition

States that when two or more waves overlap at a point, the displacement at that point is equal to the sum of the displacements of the individual waves.

Interference

The effect observed due to the superposition of two or more waves, which can be constructive or destructive.

Constructive Interference

The maximum amount of superposition occurring when waves meet in phase (peak-to-peak or trough-to-trough), resulting in added amplitudes.

Destructive Interference

The minimum amount of superposition occurring when waves meet in antiphase (peak-to-trough), resulting in the waves cancelling each other out.

Coherence

Waves that have the same frequency and a constant phase difference.

Path Difference

The difference in distance travelled by two waves from their sources to the point where they meet.

Monochromatic

Light that consists of a single wavelength.

Fringes

The bright strips (maxima) and dark strips (minima) formed on a screen due to wave interference.

Young's Double-Slit Equation

Used to calculate fringe spacing: $s = \frac{\text{λ} D}{d}$, where $s$ is fringe separation, $D$ is distance to the screen, and $d$ is slit separation.

Single-Slit Equation

Relates the angle of the first minima to wavelength and slit width: $\theta = \frac{\text{λ}}{b}$, where $b$ is the slit width.

Diffraction Grating

Optical equipment consisting of a large number of very thin, equally spaced parallel slits used to create sharp diffraction patterns.