photoelectric effect?

Question

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Answer 1

Light comes in small packages called photons that can collide with matter and move it. Among the particles with which photons of light can interact are electrons in the outer shells of atoms. Each photon has a specific amount of energy and momentum. If a photon with enough energy collides with an electron, the electron can absorb all of the energy in the photon and escape from the atom. Any leftover energy shows up as kinetic energy in the escaped photon. The liberation of these electrons from their atoms by light is called the photoelectric effect.

The energy and momentum in a photon are given by the following relationships:

E = hf
p = h / λ

where E is the photon's energy,
h is Plancks constant, which equals 6.625e-34 Joule-seconds,
f is the frequency of the photon,
p is the photon's momentum, and
λ is the wavelength.

If the above quantities are given in SI units, the energy will be in Joules and the momentum in kilogram-meters per second.

We do not measure the frequency f of light directly but usually measure and specify it in wavelengths instead. In the absence of matter, light travels at a characteristic speed c, which is 2.998e8 meters per second. In the presence of matter light slows down and its wavelength shortens but its frequency remains unchanged. In air, travels almost as fast as in a vacuum. A slight correction may be needed for precise measurements but is usually small enough to be neglected. We can calculate the frequency of light by the formula f = c / λ.

The work function of a material is the minimum energy needed to remove some of the electrons from their orbits about their atoms and produce the photoelectric effect. Light of longer wavelengths, such as far infrared, do not have enough energy in their photons to do this. More energetic photons in visible light has enough energy to produce the photoelectric effect in some materials. The light-sensitive tubes in old-fashioned video cameras, and more recently, in photosensitive semiconductor devices, depend on the photoelectric effect to operate. Other materials hold onto their electrons more tightly and require bombardment by light far into the ultraviolet before the electrons are removed from their atoms.

Answer 2

The photoelectric effect is a quantum electronic phenomenon in which electrons are emitted from matter after the absorption of energy from electromagnetic radiation such as x-rays or visible light. The emitted electrons can be referred to as photoelectrons in this context. The effect is also termed the Hertz Effect, due to its discovery by Heinrich Rudolf Hertz, although the term has generally fallen out of use.

The photons of the light beam have a characteristic energy determined by the frequency of the light. In the photoemission process, if an electron absorbs the energy of one photon and has more energy than the work function, it is ejected from the material. If the photon energy is too low, the electron is unable to escape the surface of the material. Increasing the intensity of the light beam does not change the energy of the constituent photons, only the number of photons. Thus the energy of the emitted electrons does not depend on the intensity of the incoming light, but only on the energy of the individual photons.

Electrons can absorb energy from photons when irradiated, but they follow an "all or nothing" principle. All of the energy from one photon must be absorbed and used to liberate one electron from atomic binding, or the energy is re-emitted. If the photon energy is absorbed, some of the energy liberates the electron from the atom, and the rest contributes to the electron's kinetic energy as a free particle.

Answer 3

while easy is incident on a steel floor, electrons on the floor benefit capability from the easy. If this capability is larger than the artwork function of the metallic (the capability required to loose an electron from the floor), the electron would be ejected from the floor, procuring some kinetic capability. From a wave image of light, we would assume that the form of electrons ejected and their kinetic capability could strengthen while the easy intensity is better. we would additionally assume that the frequency of the easy does not influence the kinetic capability of the ejected electrons. The particle or Einstein (he won the Nobel prize for explaining the photoelectric result, in spite of everything) image of light says that an strengthen in intensity ejects greater electrons, yet because of the fact the capability of each and every photon is unchanged, the kinetic capability of the ejected photons does not count on the intensity. besides, because of the fact the capability of a photon is h*f, the place h is Planck's consistent and f is the frequency of the easy, the kinetic capability of an ejected electron is h*f - W, the place W is the artwork function of the metallic. subsequently, if h*f < W, no electrons would be ejected, in spite of the intensity. It seems that Einstein grew to become into suitable. So, in precis, we've KE = h*f - W, it particularly is better while frequency is better (it particularly is corresponding to lowering the wavelength of the easy, yet that may no longer an answer decision), so the respond is two basically, or C. (be conscious that the form of photons incident on the floor does not count. it particularly is, basically one photon would eject one electron. So, 3 is incorrect.)

Answer 4

The velocity of an electron emitted by the photoelectric effect is given by

v = √[2(h*f - ø)/m]

m = electron mass
v = electron velocity
h = Planck's constant
f= frequency of incident light
ø = material's work function

Answer 5

are you asking what it is?

it is the quantum proof that light arrives in particles. it shows that over a certain photon (light packet) energy level (E=hf), collisions with atoms will cause an electron to be knocked off with a specific kinetic energy directly related to the energy that was in the photon.