![]() ![]() Here, intensity means frequency of observing the particle in a particular place (probability of finding the particle in a particular place. A wave function is a probability distribution. A quantum wave function is NOT the same as a typical wave as we know it in the macroscopic world, though there are similarities mathematically. But in quantum mechanics however, the probability density of a wave function is given by the amplitudes square. The *energy of a typical wave (like a real ocean wave) is given by the square of its amplitude. Like the other answer says, light is a difficult thing to describe, and there are many different properties to measure. Professor was perhaps referring to flux of an EM wave? Its flux can be thought of as the amount of something that passes through or onto something. I feel like when your professor says "number of photons per second", they are referring to the frequency of the light wave. Intensity here probably is intended to mean energy intensity- as in how luminous/energetic that light is. The term "intensity" has many meanings, and can be misleading depending on who interprets the word. Luminance is the intensity of light from a surface per unit area in a given direction. ![]() From these, the irradiance is the most natural measure, and (once you put in the suitable constants) all three versions of it are equivalent. by dividing the energy flux by the energy of each photon as given by the Planck relation $E=h\nu$ from the light's frequency $\nu$.Īs the Wikipedia page for irradiance explains in detail, there exists a huge range of radiometric measures of light intensity, depending on whether you care about the angle of emission or the spectral distribution over different frequencies or wavelengths, and so on. In microalgae low irradiance may limit photosynthesis, but high. Light intensity influences the light use efficiency. The (average) number of photons that pass through that area per unit time, $R=dN/(dt\:dA)$, is then obtained from the irradiance via The candela (cd) is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 10 12 Hz, K cd, to be 683 when expressed in the unit lm W 1, which is equal to cd sr W 1, or cd sr kg 1 m 2 s 3, where the kilogram, meter and second are defined in terms of h, c and Cs. Photons can be absorbed as energy source. power per unit area), and for a plane wave with electric-field amplitude $E_0$, the irradiance is given by how much energy passes through a unit cross-sectional area in unit time (i.e. Well set those up for this photometric light, maximize the. This is the property associated with the brightness, or intensity, of the wave. For a collimated light beam, the most relevant intensity measure is the irradiance, i.e. Instructor Among the most essential properties of any light are its intensity and color. The vertical distance between the tip of a crest and the wave’s central axis is known as its amplitude. ![]()
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