Search results
Results from the WOW.Com Content Network
Light exerts physical pressure on objects in its path, a phenomenon which can be deduced by Maxwell's equations, but can be more easily explained by the particle nature of light: photons strike and transfer their momentum. Light pressure is equal to the power of the light beam divided by c, the speed of light.
Amount of substance: n: The quantity proportional to the number of particles in a sample, with the Avogadro constant as the proportionality constant: mole (mol) N: extensive, scalar Luminous intensity: I v: Wavelength-weighted power of emitted light per unit solid angle: candela (cd) J: scalar
This is sometimes called the quantity of light. [1] Luminous energy is not the same as radiant energy , the corresponding objective physical quantity . This is because the human eye can only see light in the visible spectrum and has different sensitivities to light of different wavelengths within the spectrum.
Energy (from Ancient Greek ἐνέργεια (enérgeia) 'activity') is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light.
A photon (from Ancient Greek φῶς, φωτός (phôs, phōtós) 'light') is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force.
A physical property is any property of a physical system that is measurable. [1] The changes in the physical properties of a system can be used to describe its changes between momentary states. A quantifiable physical property is called physical quantity. Measurable physical quantities are often referred to as observables.
A physical quantity can be expressed as a value, which is the algebraic multiplication of a numerical value and a unit of measurement. For example, the physical quantity mass, symbol m, can be quantified as m=n kg, where n is the numerical value and kg is the unit symbol (for kilogram). Quantities that are vectors have, besides numerical value ...
The frequency of light used in the definition corresponds to a wavelength in a vacuum of 555 nm, which is near the peak of the eye's response to light. If the 1 candela source emitted uniformly in all directions, the total radiant flux would be about 18.40 mW , since there are 4 π steradians in a sphere.