Index of physics articles (D)

This page serves as an index to physics articles beginning with the letter "D." It is intended to aid in navigating the vast amount of information available on physics-related topics. This index includes specific topics, key concepts, significant figures, prominent physicists, important experiments, and various subfields within physics.

Entries are listed alphabetically, and the scope includes both theoretical and experimental physics. The inclusion of a term on this list does not guarantee the existence of a dedicated article; however, it indicates that the term is relevant within the domain of physics and may be discussed within other articles.

Examples of entries found within this index might include:

• D'Alembert's Principle: A principle of virtual work that states the sum of the differences between the forces acting on a system and the time derivatives of the momenta of the system itself projected onto any virtual displacement consistent with the constraints of the system, is zero.

• Dark Energy: A hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe.

• Dark Matter: A hypothetical form of matter that is thought to account for approximately 85% of the matter in the universe and about a quarter of its total mass-energy density. It is "dark" because it does not emit or interact with light.

• De Broglie Wavelength: The wavelength, λ, associated with a particle with momentum, p, and is given by λ = h/p, where h is Planck's constant.

• Decay Constant: In nuclear physics, the decay constant (λ) represents the probability per unit time that a nucleus will decay.

• Degrees of Freedom: In physics and mechanics, the number of independent parameters that define its configuration.

• Density: Mass per unit volume.

• Dielectric Constant: A measure of how much a material can reduce the electric field strength between two conductors containing equal and opposite charges.

• Diffraction: The bending of waves around obstacles or through apertures.

• Diode: A two-terminal electronic component that conducts primarily in one direction (asymmetric conductance).

• Dirac Equation: A relativistic wave equation derived by Paul Dirac in 1928.

• Dispersion: The phenomenon in which the phase velocity of a wave depends on its frequency.

• Doppler Effect: The change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source.

• Drift Velocity: The average velocity attained by charged particles in a material due to an electric field.

• Dynamics: The branch of mechanics concerned with the motion of bodies under the action of forces.