Photoelectric effect

5 Relativity • Introduction • 5.1 Invariance of Physical Laws • 5.2 Relativity of Simultaneity • 5.3 Time Dilation • 5.4 Length Contraction • 5.5 The Lorentz Transformation • 5.6 Relativistic Velocity Transformation • 5.7 Doppler Effect for Light • 5.8 Relativistic Momentum • 5.9 Relativistic Energy • Learning Objectives By the end of this section, you will be able to: • Describe physical characteristics of the photoelectric effect • Explain why the photoelectric effect cannot be explained by classical physics • Describe how Einstein’s idea of a particle of radiation explains the photoelectric effect When a metal surface is exposed to a monochromatic electromagnetic wave of sufficiently short wavelength (or equivalently, above a threshold frequency), the incident radiation is absorbed and the exposed surface emits electrons. This phenomenon is known as the photoelectric effect. Electrons that are emitted in this process are called photoelectrons. The experimental setup to study the photoelectric effect is shown schematically in photoelectrode. Photoelectrons are collected at the anode, which is kept at a higher potential with respect to the cathode. The potential difference between the electrodes can be increased or decreased, or its polarity can be reversed. The electrodes are enclosed in an evacuated glass tube so that photoelectrons do not lose their kinetic energy on collisions with air molecules in the space between electrodes. When the target material is not exposed ...

What is the photoelectric effect? Light with energy above a certain point can be used to Understanding how this works revolutionized modern physics. Applications of the photoelectric effect brought us "electric eye" door openers, light meters used in photography, solar panels and photostatic copying. Discovery Before Einstein, the effect had been observed by scientists, but they were confused by the behavior because they didn't fully understand the nature of light. In the late 1800s, physicists James Clerk Maxwell in Scotland and Hendrik Lorentz in the Netherlands determined that light appears to behave as a wave. This was proven by seeing how light waves demonstrate interference, diffraction and scattering, which are common to all sorts of waves (including waves in water.) So Einstein's argument in 1905 that light can also behave as sets of particles was revolutionary because it did not fit with the classical theory of electromagnetic radiation. Other scientists had postulated the theory before him, but Einstein was the first to fully elaborate on why the phenomenon occurred – and the implications. For example, Heinrich Hertz of Germany was the first person to see the Then in 1899, in England, J.J. Thompson demonstrated that ultraviolet light hitting a metal surface caused the ejection of electrons. A quantitative measure of the photoelectric effect came in 1902, with work by Philipp Lenard (a former assistant to Hertz.) It was clear that light had electrical properties, ...

Discussion dilemma Under the right circumstances light can be used to push electrons, freeing them from the surface of a solid. This process is called the photoelectric effect (or photoelectric emission or photoemission), a material that can exhibit this phenomenon is said to be photoemissive, and the ejected electrons are called photoelectrons; but there is nothing that would distinguish them from other electrons. All electrons are identical to one another in mass, charge, spin, and magnetic moment. The photoelectric effect was first observed in 1887 by Heinrich Hertz during experiments with a spark gap generator (the earliest device that could be called a radio). In these experiments, sparks generated between two small metal spheres in a transmitter induce sparks that jump between between two different metal spheres in a receiver. Compared to later radio devices, the spark gap generator was notoriously difficult to work with. The air gap would often have to be smaller than a millimeter for a the receiver to reliably reproduce the spark of the transmitter. Hertz found that he could increase the sensitivity of his spark gap device by illuminating it with visible or ultraviolet light. Later studies by J.J. Thomson showed that this increased sensitivity was the result of light pushing on electrons — a particle that he discovered in 1897. While this is interesting, it is hardly amazing. All forms of electromagnetic radiation transport energy and it is quite easy to imagine th...

The energy of the incident photon must be equal to the sum of the metal's work function and the photoelectron kinetic energy: E photon = KE electron + Φ \text+\Phi E photon ​ = KE electron ​ + Φ start text, E, end text, start subscript, start text, p, h, o, t, o, n, end text, end subscript, equals, start text, K, E, end text, start subscript, start text, e, l, e, c, t, r, o, n, end text, end subscript, plus, \Phi When light shines on a metal, electrons can be ejected from the surface of the metal in a phenomenon known as the photoelectric effect. This process is also often referred to as photoemission, and the electrons that are ejected from the metal are called photoelectrons. In terms of their behavior and their properties, photoelectrons are no different from other electrons. The prefix, photo-, simply tells us that the electrons have been ejected from a metal surface by incident light. To explain the photoelectric effect, 19th-century physicists theorized that the oscillating electric field of the incoming light wave was heating the electrons and causing them to vibrate, eventually freeing them from the metal surface. This hypothesis was based on the assumption that light traveled purely as a wave through space. (See If a single large wave were to shake the dock, we would expect the energy from the big wave would send the beach balls flying off the dock with much more kinetic energy compared to a single, small wave. This is also what physicists believed would happen if...

[ "article:topic", "authorname:openstax", "cut-off frequency", "cut-off wavelength", "energy of a photon", "photocurrent", "Photoelectric effect", "photoelectrode", "photoelectron", "photon", "quantum phenomenon", "stopping potential", "work function", "license:ccby", "showtoc:no", "program:openstax", "licenseversion:40", "source@https://openstax.org/details/books/university-physics-volume-3" ] \( \newcommand\) • • • • • • • • • • • • • • Learning Objectives By the end of this section you will be able to: • Describe physical characteristics of the photoelectric effect • Explain why the photoelectric effect cannot be explained by classical physics • Describe how Einstein’s idea of a particle of radiation explains the photoelectric effect When a metal surface is exposed to a monochromatic electromagnetic wave of sufficiently short wavelength (or equivalently, above a threshold frequency), the incident radiation is absorbed and the exposed surface emits electrons. This phenomenon is known as the photoelectric effect. Electrons that are emitted in this process are called photoelectrons. The experimental setup to study the photoelectric effect is shown schematically in Figure \(\PageIndex\): An experimental setup to study the photoelectric effect. The anode and cathode are enclosed in an evacuated glass tube. The voltmeter measures the electric potential difference between the electrodes, and the ammeter measures the photocurrent. The incident radiation is monochromatic. When t...

Consider how Heinrich Hertz's discovery of the photoelectric effect led to Albert Einstein's theory of light photoelectric effect, phenomenon in which electrically charged particles are released from or within a material when it absorbs Discovery and early work The photoelectric effect was discovered in 1887 by the German physicist photoelectric) was clarified in 1902 by another German physicist, Further research showed that the photoelectric effect represents an interaction between light and matter that cannot be explained by classical physics, which describes light as an electromagnetic wave. One inexplicable observation was that the maximum Physics and Natural Law Einstein assumed that a photon would penetrate the material and transfer its energy to an E k = h f − ϕ, where E k is the maximum kinetic energy of the ejected electron. Although Einstein’s model described the emission of electrons from an illuminated plate, his photon h was the same as Get a Britannica Premium subscription and gain access to exclusive content. In 1922 the American physicist Photoelectric principles According to see see Photoconductivity arises from the electrons freed by the light and from a flow of positive charge as well. Electrons raised to the conduction band correspond to missing negative charges in the valence band, called “holes.” Both electrons and holes increase current flow when the In the p- n junction rather than a pure semiconductor. A p- n junction occurs at the juncture between...