Electromagnetic radiation and quantum phenomena key terms

photoelectron emission

The release of electrons from a metal surface when it absorbs energy from incident photons.

threshold frequency

The minimum frequency of incident light required to emit photoelectrons from a metal surface, related to the work function of the metal.

Threshold Frequency

The minimum frequency of incident photons required to emit electrons from a metal surface, related to the work function.

Work Function

The minimum energy required to remove an electron from the surface of a metal, typically measured in electron volts (eV).

photoelectric effect

The phenomenon where electrons are emitted from a metal surface when it is exposed to light of sufficient frequency.

threshold frequency

The minimum frequency of incident light required to emit electrons from a metal surface in the photoelectric effect.

wave theory

A classical physics model that describes light as a wave, which fails to explain the photoelectric effect.

photoelectric observations

Key experimental results that demonstrate the emission of electrons from a metal surface when exposed to light, contradicting wave theory predictions.

Excitation

The process in which an electron in an atom absorbs energy and moves to a higher energy level without being removed from the atom.

Ionisation

The process in which an electron is completely removed from an atom, resulting in the formation of a charged ion.

electron collision

The interaction between an electron and an atom that can result in energy transfer.

discrete energy transfer

The transfer of specific, quantized amounts of energy during electron collisions with atoms.

electron volt

A unit of energy equal to the amount of kinetic energy gained by an electron when it is accelerated through a potential difference of one volt.

ionisation energy

The minimum energy required to remove an electron from an atom or ion in its gaseous state.

collision energy

The energy transferred during a collision between particles, which can lead to atomic transitions.

atomic transition

The process where an electron moves between energy levels in an atom, often resulting in the emission or absorption of a photon.

photon emission

The process by which an electron transitions from a higher to a lower energy level, releasing energy in the form of a photon.

energy levels

Discrete quantized states that electrons occupy in an atom, where transitions between these levels result in the absorption or emission of energy.

photon energy

The energy of a photon, calculated as the difference between two energy levels in an atom, given by the formula E = hf, where E is energy, h is Planck's constant, and f is frequency.

energy levels

Discrete levels of energy that electrons can occupy in an atom, with transitions between these levels resulting in the emission or absorption of photons.

line spectrum

A spectrum that consists of discrete lines, each representing a specific wavelength emitted by electrons transitioning between energy levels in an atom.

discrete energy levels

Specific energy states that electrons can occupy in an atom, where transitions between these levels result in the emission or absorption of photons.

Energy Level Diagram

A graphical representation showing the energy levels of electrons in an atom, indicating possible transitions between levels.

Photon Emission

The process by which an electron transitions from a higher energy level to a lower energy level, releasing energy in the form of a photon.

wave-particle duality

The concept that particles, such as electrons, exhibit both wave-like and particle-like properties.

electron diffraction

The phenomenon where electrons exhibit wave behavior, resulting in interference patterns when passing through narrow openings or around obstacles.

de Broglie wavelength

The wavelength associated with a moving particle, calculated using the de Broglie equation: λ = h / p, where h is Planck's constant and p is momentum.

momentum

A physical quantity defined as the product of an object's mass and its velocity, expressed as p = m × v, where p is momentum, m is mass, and v is velocity.

electron diffraction

The phenomenon where electrons exhibit wave-like behavior, resulting in interference patterns when passed through a narrow slit or around an obstacle.

wave-particle duality

The concept in quantum mechanics that describes how particles, such as electrons, exhibit both wave-like and particle-like properties depending on the experimental conditions.