Flashcard: Fundamentals of Light: Wave, Interference, and Diffraction — 24 carte

Wave-particle duality of light

Light exhibits both wave and particle properties.

Wave nature of light

Light propagates as an electromagnetic wave.

Particle nature of light

Light consists of photons, discrete energy quanta.

Wave-front — definition?

Surface of constant phase in a wave.

Wave-front propagation

Movement of wave-fronts indicating wave travel direction.

Huygen’s principle — role?

Wave-fronts are formed by secondary wavelets from each point.

Light interference — requirement?

Requires coherent, monochromatic sources.

Interference pattern — cause?

Superposition of coherent light waves.

Young’s double slit — purpose?

Demonstrates interference with bright and dark fringes.

Fringe spacing formula

Δy = (λ D)/d, relates wavelength, distance, slit separation.

Interference conditions — key?

Coherence, monochromaticity, proper path difference.

Young’s experiment — significance?

Proves wave nature of light via interference fringes.

Interferometer — function?

Splits and recombines light to measure small distances.

Michelson interferometer — use?

Detects tiny path differences, measures distances or gravitational waves.

Gravitational waves — origin?

Ripples in spacetime from accelerating massive objects.

Detection of gravitational waves

Using laser interferometers to observe spacetime distortions.

Diffraction of light — phenomenon?

Light bends and spreads around obstacles or through slits.

Diffraction through slit — pattern?

Central bright maximum with successive dimmer fringes.

Diffraction grating — purpose?

Disperses light into spectrum via multiple slits.

Bragg’s law — equation?

2 d sin θ = m λ, for constructive X-ray diffraction.

Polarisation of light — property?

Electric field oscillates in a single plane.

Unpolarised vs polarised light

Unpolarised: random electric oscillations; Polarised: single plane.

Polarisation by reflection — condition?

At Brewster’s angle, reflected light becomes polarised.

Malus’s law — formula?

I = I₀ cos²θ, describes intensity after polariser.