Waves, Quantum Concepts, and Photoelectric Effect (Vocabulary Flashcards)

A set of vocabulary flashcards covering waves, quantum concepts, and the photoelectric effect drawn from the lecture notes.

Wave

A propagating dynamic disturbance of one or more quantities.

Periodic wave

A wave whose disturbance repeats cyclically about an equilibrium value.

Traveling wave

A wave whose disturbance moves through space and time in one direction (examples include light and ocean waves).

Stationary wave

A wave that oscillates in place (for example on a guitar string).

Wavelength

Distance between equivalent points on successive cycles.

Frequency

Number of oscillations per unit time.

Amplitude

Maximum displacement from the equilibrium position.

Determinism

If initial conditions and forces are known, the future history can be predicted.

Continuous quantities

Physical quantities such as energy, acceleration, and momentum that can vary continuously.

Oscillators

Entities that emit or absorb energy; in solids atoms vibrate around equilibrium positions acting as oscillators.

Light

Light or radiation is described as a wave in classical theory.

Photon

A quantum of light energy; a particle with energy E = h f.

Wave-particle duality

Light can behave as both a wave and particles depending on conditions.

Planck constant h

Fundamental constant; energy of a photon is E = h f; h ≈ 6.626×10^-34 J·s.

Quantization

Energy is emitted or absorbed in discrete units equal to multiples of h f.

Photoelectric effect

Emission of electrons when light shines on a material, usually a metal.

Work function

Minimum energy required to eject an electron from a metal surface.

Threshold frequency

Minimum light frequency required to eject an electron; photons with lower frequency do not cause emission.

Intensity

Light intensity is proportional to the number of photons; higher intensity means more photons; each photon energy depends on frequency.

de Broglie hypothesis

All moving objects have matter waves; wavelength λ = h/p.

de Broglie wavelength

Wavelength associated with a moving particle; λ = h/p.

Bohr model

Atomic model with discrete energy levels; electrons occupy orbitals and can jump between levels but not reside in between.

Energy levels

Specific discrete energy values allowed for electrons in an atom.

Ground state

The lowest energy level, designated N = 1.

Electron transition

Electron moves between energy levels; photon energy equals the difference between levels during absorption or emission.

Emission

Photon emission as an electron drops to a lower energy level.