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Wave-particle duality is one of the most important ideas in quantum theory. It states that, just as light has the properties of wave and particle, so matter also has those two properties, which have been observed not only in elementary particles but also in complex ones, such as atoms and molecules.
The concept of the wave-particle duality of light says that light possesses both wave and particle properties, even though we cannot observe both at the same time.
Light mostly acts as a wave, but it may also be thought of as a collection of small energy packets known as photons. Photons have no mass but convey a set quantity of energy.
The amount of energy carried by a photon is directly proportional to the photon's frequency and inversely proportional to its wavelength. To calculate a photon's energy, we use the following equations:
where:
where:
The four classical light properties as a wave are reflection, refraction, diffraction, and interference.
If the surface is flat and bright, as in the case of water, glass, or polished metal, the light will be reflected at the same angle at which it hit the surface. This is known as specular reflection.
Diffuse reflection, on the other hand, is when light strikes a surface that is not as flat and bright and reflects in many different directions.
A real-life example of reflection. flickr.com
A real-life example of refraction. flickr.com
Interference occurs when light meets an obstacle that contains two tiny slits separated by a distance d . The wavelets emanating towards each other interfere either constructively or destructively.
If you put a screen behind the two tiny slits, there will be dark and bright stripes, with the dark stripes being caused by constructive interference and the bright stripes by destructive interference.
Two-slit interference pattern. -StudySmarter Originals
Current scientific thinking, as advanced by Max Planck, Albert Einstein, Louis de Broglie, Arthur Compton, Niels Bohr, Erwin Schrödinger, and others, holds that all particles have both a wave and a particle nature. This behavior has been observed not just in elementary particles but also in complex ones, such as atoms and molecules.
In 1900, Max Planck formulated what is known as Planck's radiation law to explain the spectral-energy distribution of a blackbody's radiation. A blackbody is a hypothetical substance, which absorbs all radiant energy that strikes it, cools to an equilibrium temperature, and re-emits the energy as rapidly as it receives it.
Given Planck's constant (h = 6.62607015 * 10 ^ -34), the speed of light (c = 299792458 m / s), the Boltzmann constant (k = 1.38064852 * 10 ^ -23m ^ 2kgs ^ -2K ^ -1), and the absolute temperature (T), Planck's law for energy Eλ emitted per unit volume by a cavity of a blackbody in the wavelength interval from to λ + Δλ may be expressed as follows:
Most of the radiation emitted by a blackbody at temperatures up to several hundred degrees is in the infrared region of the electromagnetic spectrum. At increasing temperatures, the total radiated energy rises, and the intensity peak of the emitted spectrum changes to shorter wavelengths, resulting in visible light being released in greater amounts.
While Planck used atoms and a quantized electromagnetic field to solve the ultraviolet crisis, most modern physicists concluded that Planck's model of 'light quanta' had inconsistencies. In 1905, Albert Einstein took Plank's blackbody model and used it to develop his solution for another massive problem: the photoelectric effect. This says that when atoms absorb energy from light, electrons are emitted from atoms.
Einstein's explanation of the photoelectric effect: Einstein provided an explanation for the photoelectric effect by postulating the existence of photons, quanta of light energy with particulate qualities. He also stated that electrons could receive energy from an electromagnetic field only in discrete units (quanta or photons). This led to the equation below:
where E is the amount of energy, f is the frequency of light (Hertz), and his Planck's constant (6.626 * 10 ^ -34).
In 1924, Louis-Victor de Broglie came up with de Broglie's hypothesis, which made a big contribution to quantum physics and said that small particles, such as electrons, can display wave properties. He generalized Einstein's equation of energy and formalized it to obtain the wavelength of a particle:
where λ is the particle's wavelength, h is Planck's constant (6.62607004 * 10 ^ -34 m ^ 2 kg / s), and m is the mass of the particle moving at a velocity v.
In 1927, Werner Heisenberg came up with the uncertainty principle, a central idea in quantum mechanics. According to the principle, you can't know the exact position and the momentum of a particle at the same time. His equation, where Δ indicates standard deviation, x and p are a particle's position and linear momentum respectively, and his Planck's constant (6.62607004 * 10 ^ -34 m ^ 2 kg / s), is shown below.
Light can be understood both as a wave and a particle.
Louis de Broglie suggested that electrons and other discrete pieces of matter, which had formerly only been thought of as material particles, had wave characteristics, such as wavelength and frequency.
Light and matter have properties that are both wavelike and particle-like.
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