Video Notes: Photoelectric Effect, Collisions, Energy Levels, and Wave-Particle Duality (VOCABULARY flashcards)

Vocabulary flashcards covering key terms and definitions from the notes on the photoelectric effect, electron collisions, energy levels, and wave–particle duality.

Work function (φ)

Minimum energy required for an electron to escape from the surface of a metal.

Einstein’s photoelectric equation

hf = φ + E_k; the energy of the incoming photon equals the work function plus the kinetic energy of the emitted electron.

Threshold frequency (f0)

Minimum frequency of incident photons required to cause emission; determined by hf0 = φ.

Planck’s constant (h)

Proportionality constant relating energy and frequency: E = h f; h ≈ 6.63 × 10^-34 J·s.

Photon energy

Energy carried by a photon, given by E = h f.

Electron volt (eV)

Energy gained by an electron when moved through a potential difference of 1 volt; 1 eV = 1.6 × 10^-19 J.

Ionisation

Removal of an electron from an atom, producing a positively charged ion.

Excitation

Movement of an electron to a higher energy level within an atom.

Ways to excite electrons

Excitation can occur via collision with another electron or by absorbing a photon of the correct frequency.

Fluorescent tube

Contains mercury gas; accelerated electrons ionise mercury; UV photons are emitted and absorbed by a phosphor coating to emit visible light.

Phosphor coating

Inside a fluorescent tube; absorbs UV photons and re-emits visible light.

Line spectrum

A set of characteristic wavelengths emitted or absorbed by the atoms of an element.

Energy levels in atoms

Discrete energy levels; electrons transition between them, emitting or absorbing photons.

De-excitation

Transition of an electron from a higher to a lower energy level, emitting a photon.

Ground state

The lowest energy state of an atom (n = 1 for hydrogen).

De Broglie wavelength

Wavelength associated with a moving particle; λ = h/p (non-relativistic: p = mv).

Electron diffraction

Experiment showing the wave nature of electrons; produces a diffraction pattern similar to light.

Wave–particle duality

Concept that light and matter exhibit both wave-like and particle-like properties.

Four wave-like behaviours of light

Reflection, Refraction, Diffraction, and Interference.

Infrared region

Region of the electromagnetic spectrum with frequencies longer than visible light; example frequency around 2.6 × 10^14 Hz.

Photon

Quantum/particle description of light; a quantum of electromagnetic radiation.

Energy of a photon in a transition

The energy difference between two levels equals the energy of the emitted/absorbed photon: ΔE = h f.