Physics: Wave-Particle Duality and the Photoelectric Effect

Flashcards covering vocabulary and key concepts of wave-particle duality, quantum theory of light, the photoelectric effect, and de Broglie waves as detailed in the lecture notes.

Wave particle duality of matter

The concept that every elementary particle or quantic entity may be partly described in terms not only of particles but also waves.

Photoelectric effect

The process of emitting electrons from a metal surface when the metal surface is exposed to electromagnetic radiation of sufficiently high energy.

Young's two slit experiment

An experiment used to demonstrate that light moves as a wave.

de-Broglie hypothesis

The hypothesis stating that a particle in motion can be treated as a wave, and that all matter possesses both particle and wave nature, quantified by the wavelength $\lambda = \frac{h}{p}$.

Photons

Small packets of light energy where each packet of frequency $v$ has the energy $hv$, equivalent to Planck's quantum energy.

Work function ($w_0$)

The minimum energy needed to take an electron from a state to vaccum, represented by the formula $w_0 = hv_0$.

Threshold Frequency ($v_0$)

The minimum frequency (or critical frequency) of incident radiation below which no photoelectrons are emitted from a particular metal surface.

Einstein's photoelectric equation

The equation $hf = hf_0 + K.E.$ which describes how incident photon energy is used to free an electron and provide it with kinetic energy.

Group velocity ($v_g$)

The speed at which a wave's envelope or packet travels through space, representing the rate at which energy is transferred by the wave.

Phase velocity ($v_p$)

The rate at which the phase of a wave propagates in space, defined as $v_p = \frac{\omega}{k}$.

Photo-emissive cell

Commonly known as a photo-tube, this device uses the photoelectric effect to emit electrons from a cathode when struck by light rays.

Photo-voltaic cell

A device, also called a solar cell, that generates a small voltage when light strikes the junction between a metal and a semiconductor.

Photo-conductive cell

Also known as photo-resistors, these contain thin films of semiconductor materials whose electrical conductivity increases when exposed to light.

Davisson and Germer experiment

An experimental verification of the de-Broglie hypothesis conducted by scattering electrons from a nickel crystal target to observe diffraction patterns.

Dispersive medium

A medium in which different wavelengths of light travel with different velocities.

Bohr atom (Classical Failure)

A phenomenon classical mechanics failed to explain, as it predicted that an electron in a Bohr orbit would lose energy and spiral into the nucleus in approximately $10^{-10}$ seconds.

Bragg equation

The equation used for determining diffraction pattern maxima, given as $n\lambda = 2d\sin(\theta)$, used to analyze electron diffraction in the Davisson-Germer experiment.