Light wavelike properties

Quantum mechanics began with a daring hypothesis by Louis de Broglie (he was a student at the time) if light has a dualistic wave/particle nature, why not matter His reasoning led to the prediction that a particle of mass m and velocity V would exhibit wavelike properties with wavelength... 

In addition to its wavelike properties, light also exhibits particle-like properties, such as for the photoelectric effect. Thus light can act as if it were divided — or quantized — into discrete units, which we call photons. The light energy (Ex) carried by a photon is... 

Optical reflection is best understood in terms of the wavelike properties of light. The electric field vector associated with the wave oscillates in a plane as the wave propagates (Figure 17.1.6), and the intensity of the light is proportional to the square of the electric... 

The answers to the above questions, not all of which need he presented here, were formulated between 1925 and 1926, in the revolution of modern quantum theory, which shook the foundations of physics and philosophy. Remarkably, the central theme of quantum theory was the nature of light, and what came to be called the wave-particle duality. But other broader implications of the new theory existed, and the first inkling of this was given in 1924 by Louis de Broglie (Fig. 3.26) in his doctoral dissertation. He postulated that particles may also possess wavelike properties and that these wavelike properties would manifest themselves only in phenomena occurring on an atomic scale, as dictated by Planck s constant. He also postulated that the wavelength of these matter waves, for a given particle such as an electron or proton, would be inversely proportional to the particle s momentum p, which is a product of its mass m and speed... 

In 1924, Louis de Broglie (1892-1987), studying at the Sorhonne, published his doctoral thesis in which he proposed an essential s)mimetry in nature Just as electromagnetic radiation (e.g., visible light. X-rays), commonly analyzed as waves, exhibits particle-like properties, matter may exhibit wavelike properties. The wavelength of such de Broglie... 

We learn that light (radiant energy, or electromagnetic radiation) has wavelike properties and is characterized by wavelength, frequency, and speed. 

De Broglie reasoned that if light waves could behave like a stream of particles (photons), then perhaps particles such as electrons could possess wavelike properties. To quantify this connection, de Broglie began with the expression (from Einstein s theory of special relativity) for the momentum (jp) of the photon ... 

At about the same time, Schrodinger developed what came to be known as wave mechanics. Already in 1924, the French physicist Prince Louis De Broglie had suggested an analogy to Albert Einstein s earlier discovery that light waves have a particulate nature as well as their expected wave nature. De Broghe made the association run in the opposite sense. Why not suppose that particles such as electrons could likewise display wavelike properties The test for this idea would be to demonstrate experimentally that electrons produce diffraction and interference effects just hke classical waves, such as waves on the surface of water. ... 

Soon afterward, other phenomena such as Compton scattering. X-ray production, pair creation and annihilation could be interpreted successfully using a photon picture of light. Light still retains its wavelike properties as it travels through space. It assumes its photon or particle-like behavior only when it interacts with matter in a detector or at a target. 

Wave-particle duality means that matter has wavelike properties (as shown by the de Broglie wavelength and electron diffraction] and energy has particlelike properties (as shown by photons of light having momentum). These properties are observable only on the atomic scale, and because of them, we can never simultaneously know the position and speed of an electron in an atom (uncertainty principle). (Section 7.3)... 

Before 1900, scientists thought light behaved solely as a wave. This belief changed when it was later discovered that light also has particle-like characteristics. StiU, many of UghTs properties can be described in terms of waves. A quick review of these wavelike properties will help you understand the basic theory of light as it existed at the beginning of the twentieth century. 

In 1905, Albert Einstein expanded on Planck s theory by introducing the radical idea that electromagnetic radiation has a dual wave-particle nature. Light exhibits many wavelike properties, but it can also be thought of as a stream of particles. Each particle carries a quantum of energy. 

In Chapter 6 we learned that although an electron is a particle with a known mass, it exhibits wavelike properties. The quantum mechanical model of the atom, which gives rise to the fainiliar shapes of s and p atomic orbitals, treats electrons in atoms as waves, rather than particles. Therefore, rather than use arrows to denote the locations and spins of electrons, we will adopt a convention whereby a singly occupied orbital will appear as a light color and a doubly occupied... 

It is the wavelike properties of the electrons that cause two atomic orbitals to form two molecular orbitals. Two atomic orbitals can combine in an additive (constractive) manner, just as two light waves or two sound waves can reinforce each other (Figure 1.3a). The constructive combination of two s atomic orbitals is called a a (sigma) bonding molecular orbital. 

At the beginning of the 20 century, experimentation revealed that electromagnetic radiation has particle-like properties (as an example, photons were shown to be deflected by gravitational fields), and as a result, it was theorized that all particles must also have wavelike properties. The idea that particles have waveUke properties resulted from the observation that a monoenergetic beam of electrons could be diffracted in the same way a monochromatic beam of light can be diffracted. The diffraction of light is a result of its wave character hence, there must be an abstract type of wave... 

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