Light and the Photoelectric Effect Fifth

Flashcards covering key vocabulary related to light, wave-particle duality, and the photoelectric effect, based on lecture notes.

Visible Light

The portion of the electromagnetic spectrum that is visible to the human eye, generally ranging from 380 nm to 740 nm, encompassing various colors.

Red Light

Visible light with a wavelength range of 640-700 nm.

Orange Light

Visible light with a wavelength range of 600-640 nm.

Yellow Light

Visible light with a wavelength range of 560-600 nm.

Green Light

Visible light with a wavelength range of 450-560 nm.

Blue Light

Visible light with a wavelength range of 450-480 nm.

Violet Light

Visible light with a wavelength range of 400-450 nm.

Particle Behavior (of light)

Light acting as discrete packets of energy called photons.

Wave Behavior (of light)

Light acting as a propagating disturbance characterized by properties like wavelength and frequency, demonstrated by phenomena such as diffraction.

Diffraction

The bending of waves as they pass around an obstacle or through an aperture, observed in light when passing through a slit.

Thomas Young

A scientist who, in 1801, demonstrated light's wave nature through experiments showing interference patterns from two slits.

Interference

The phenomenon where two or more waves superpose to form a resultant wave of greater, lower, or the same amplitude.

Constructive Interference

Occurs when waves in phase combine to make a bright spot, characterized by equal path lengths.

Destructive Interference

Occurs when waves out of phase combine to make a dark spot, characterized by path lengths differing by half a wavelength (λ/2).

Frequency (ν)

The number of wave cycles per unit time, measured in Hertz (Hz) or inverse seconds (s⁻¹).

Wavelength (λ)

The spatial period of a wave, the distance over which the wave's shape repeats, measured in meters (m) or nanometers (nm).

Energy (E)

The capacity to do work; for light, it is related to frequency by the equation E = hν, measured in Joules (J) or electron-volts (eV).

Speed of Light (c)

A universal physical constant representing the speed at which electromagnetic radiation propagates in a vacuum, approximately 2.99792458 × 10⁸ m/s.

Planck's Constant (h)

A fundamental physical constant relating the energy of a photon to its frequency, approximately 6.626 × 10⁻³⁴ Js.

Albert Einstein

A scientist who, in 1905, proposed that light is a particle (photon) to explain the photoelectric effect.

Photoelectric Effect

The phenomenon where electrons are ejected from a material's surface when light shines on it, provided the light has sufficient energy (frequency).

Photon

A quantum of light or other electromagnetic radiation, conceived as a particle having zero rest mass and energy E = hν.

Photoelectric Effect Equation

Ephoton = Φ + ½mv², where Ephoton is the photon energy, Φ is the work function, and ½mv² is the kinetic energy of the ejected electron.

Work Function (Φ)

The minimum amount of energy required to eject an electron from the surface of a material (e.g., 2.0 eV for Potassium).

Threshold Frequency (ν₀)

The minimum frequency of incident light required to cause the photoelectric effect; below this frequency, no electrons are ejected.

Threshold Wavelength (λ₀)

The maximum wavelength of incident light that can cause the photoelectric effect; above this wavelength, no electrons are ejected.

Solar Cell

A device that converts light energy into electrical energy through the photoelectric effect, causing electrons to flow.

Solar Panels

An array of solar cells designed to convert solar energy into electricity.