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The photoelectric effect occurs when photons with sufficient energy strike a metal surface, causing electrons to be emitted. According to the Einstein photoelectric equation, the energy of the emitted electron is equal to the energy of the incident photon minus the work function of the metal. Therefore, only photons with energy greater than the work function of the metal can overcome the binding energy of the electrons and cause emission. This is why electrons are emitted only when the frequency (or energy) of the incident radiation is greater than a certain value.
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Why the wave model for radiation does not account for the photoelectric effect?
Predictions of the wave model: Energy of light was dependent on the amplitude of the light wave, which was manifested as the brightness of the light. Higher amplitude (brighter) light would cause the ejected electrons to be more energetic. Colour of light was dependent on the frequency of the light but frequency had no bearing on the energy of the ejected photons. Predictions of the photon model: Both the energy of light and the colour of light was dependent on the frequency of the photons. Higher frequency would cause the the ejected electrons to be more energetic. The number of photons was manifested as the brightness of the light. Higher number of photons (brighter) light would cause the ejected electrons to be more numerous (higher current). Observations from the photoelectric effect experiment: Ejected electron energy was directly related to the frequency of the light and brighter light resulted in higher current. These observations were explained by the photon model and could not be explained with the wave model.
Why for a particular metal electrons are emitted only when the frequency of the incident radiation is greater than a certain value?
Electrons are emitted from a metal surface when the energy of the incident photons is great enough to overcome the work function of the metal. This minimum energy required is equivalent to a certain threshold frequency, known as the threshold frequency. Electrons can only be emitted when the frequency of the incident radiation is greater than this threshold frequency because lower frequency photons do not possess enough energy to overcome the work function and release electrons from the metal surface.
What is the photoelectric effect?
The photoelectric effect is the phenomenon where electrons are emitted from a material when it is exposed to light or electromagnetic radiation. This effect was explained by Albert Einstein in 1905 and is a key principle in understanding the behavior of light and electrons.
The wave model of light does not explain what?
It does not explain the photoelectric effect. According to the wave theory, given light of sufficient intensity, electrons should be emitted from the surface of a metal. What is observed though, is that given light of sufficient frequency, electrons will be emitted from the metal surface independent of intensity. If the frequency is too low, electrons will NOT be emitted even if the highest intensity of light was used. Albert Einstein suggested that it would be possible to explain the photoelectric effect if light was considered to be made up of particles instead of waves. The energy of the particles of light, called photons, would be proportional to the frequency of the light. Electrons would be emitted from the metal only if the energy of ONE photon was sufficient for the electron on the metal surface to break bonds and escape from the surface. Otherwise, the photons will rebound on the metal surface with no emission of electrons. Einstein 'mathematised' the photoelectric effect in the following equation: hf = Ekmax + o where h is the planck constant f is the frequency of the radiation Ekmax is the maximum kinetic energy of the emitted electrons o is the work-function energy, that is the minimum energy required for the electron to escape from the metal surface. Note: hf is the energy of a photon. It was for the explanation of the photoelectric effect that Einstein was awarded the Nobel prize in Physics in 1921. (and not for his still greater discoveries in relation to relativity)
What types of radiation has the highest frequency?
In the electromagnetic spectrum Gamma radiation has the highest frequency.
What is the threshold frequency of cesium?
The threshold frequency of cesium is approximately 3.3 x 10^14 Hz. This is the minimum frequency of electromagnetic radiation required to eject electrons from the surface of cesium via the photoelectric effect.
Why the wave model for radiation does not account for the photoelectric effect?
Predictions of the wave model: Energy of light was dependent on the amplitude of the light wave, which was manifested as the brightness of the light. Higher amplitude (brighter) light would cause the ejected electrons to be more energetic. Colour of light was dependent on the frequency of the light but frequency had no bearing on the energy of the ejected photons. Predictions of the photon model: Both the energy of light and the colour of light was dependent on the frequency of the photons. Higher frequency would cause the the ejected electrons to be more energetic. The number of photons was manifested as the brightness of the light. Higher number of photons (brighter) light would cause the ejected electrons to be more numerous (higher current). Observations from the photoelectric effect experiment: Ejected electron energy was directly related to the frequency of the light and brighter light resulted in higher current. These observations were explained by the photon model and could not be explained with the wave model.
Why for a particular metal electrons are emitted only when the frequency of the incident radiation is greater than a certain value?
Electrons are emitted from a metal surface when the energy of the incident photons is great enough to overcome the work function of the metal. This minimum energy required is equivalent to a certain threshold frequency, known as the threshold frequency. Electrons can only be emitted when the frequency of the incident radiation is greater than this threshold frequency because lower frequency photons do not possess enough energy to overcome the work function and release electrons from the metal surface.
What is the reverse process of photoelectric effect?
reverse process of photo electric effect is done by the supply of electrons or heat to the metal that radiate certain radiation. among them the metals which emit visible radiation are normally used in house hold appliances
Why there is a cutoff requency in the photoelectric effect?
In any circumstance where a threshold of energy is required to free an electron from a bound state, an incoming photon must have at least that energy to do the job. The energy of a photon is proportional to the frequency of the light, so the minimum energy corresponds to a minimum frequency of the light, or maximum wavelength necessary to free an electron. This observation was a major step in the development of radiation theory (Einstein).
Can photoelectric effect be observed using infrared rays?
No, the photoelectric effect is the emission of electrons from a material due to the absorption of photons. Infrared rays have lower energy photons than visible light, so they are not typically energetic enough to cause the photoelectric effect. Only photons with enough energy, such as ultraviolet or higher energy photons, can induce the photoelectric effect.
When electromagnetic radiation above the threshold frequency falls on an object it emits electrons?
Hhn
What is the photoelectric effect?
The photoelectric effect is the phenomenon where electrons are emitted from a material when it is exposed to light or electromagnetic radiation. This effect was explained by Albert Einstein in 1905 and is a key principle in understanding the behavior of light and electrons.
The wave model of light does not explain what?
It does not explain the photoelectric effect. According to the wave theory, given light of sufficient intensity, electrons should be emitted from the surface of a metal. What is observed though, is that given light of sufficient frequency, electrons will be emitted from the metal surface independent of intensity. If the frequency is too low, electrons will NOT be emitted even if the highest intensity of light was used. Albert Einstein suggested that it would be possible to explain the photoelectric effect if light was considered to be made up of particles instead of waves. The energy of the particles of light, called photons, would be proportional to the frequency of the light. Electrons would be emitted from the metal only if the energy of ONE photon was sufficient for the electron on the metal surface to break bonds and escape from the surface. Otherwise, the photons will rebound on the metal surface with no emission of electrons. Einstein 'mathematised' the photoelectric effect in the following equation: hf = Ekmax + o where h is the planck constant f is the frequency of the radiation Ekmax is the maximum kinetic energy of the emitted electrons o is the work-function energy, that is the minimum energy required for the electron to escape from the metal surface. Note: hf is the energy of a photon. It was for the explanation of the photoelectric effect that Einstein was awarded the Nobel prize in Physics in 1921. (and not for his still greater discoveries in relation to relativity)
Is it possible to convert heat energy to electrical energy directly?
I am just speculating ok. Heat energy can take the form of radiation of electromagnetic waves. there is a well known phenomenon called the photoelectric effect, which means that by concentrating radiation at a specific frequency on a certain element the photons kicks the free electrons out the element causing it to shine due to the released electrons. this could be a way of converting heat energy directly to electrical energy.
Is frequency related to radiation?
yes frequency = 1/radiation
Why you need quantum mechanics or modern physics while classical physics existed already?
Because there were a couple of things observed that were inexplicable with classical physics, namely: Blackbody radiation - Radiated energy doesn't continually increase as the frequency of the radiation increases. Classically, this relationship is given by the Rayleigh-Jeans Law, however, this law goes to infinity as frequency goes to infinity. The Photoelectric Effect - The energy of electrons emitted from a surface when a light is shined on it had nothing to do with the light's intensity, just it's frequency. Quantizing electromagnetic energy was the only way to explain these phenomena.
