Questions tagged [photoelectric-effect]

The observed behavior in which light falling on certain metals can eject electrons from the surface.

Filter by
Sorted by
Tagged with
49
votes
9answers
10k views

Can the photoelectric effect be explained without photons?

Lamb 1969 states, A misconception which most physicists acquire in their formative years is that the photoelectric effect requires the quantization of the electromagnetic field for its explanation. ...
29
votes
5answers
4k views

Photoelectricity in daily life

Photons strike metals innumerable times in our day-to-day experience.Then, why photoelectrons do not come out of metal surface and cause current?
27
votes
3answers
14k views

Is plant photosynthesis more efficient than solar panels?

Is photosynthesis more efficient than solar panels? If so, by how much?
13
votes
6answers
27k views

Compton scattering vs. photoelectric effect

Say a photon hits some atom. What determines whether there will be a photoelectric effect (photon is absorbed, electron is released) or whether there will be a Compton scattering (the photon is ...
13
votes
2answers
26k views

How would I calculate the work function of a metal?

In the photoelectric effect, the work function is the minimum amount of energy (per photon) needed to eject an electron from the surface of a metal. Is it possible to calculate this energy from the ...
13
votes
3answers
18k views

Why doesn't photoelectric current increase with frequency of the incident wave?

If the frequency of the incident wave is increased, then the kinetic energy of the photoelectrons increases. If so, why doesn't the photoelectric current increase? If the kinetic energy of electrons ...
12
votes
5answers
2k views

Photoelectric effect, low frequency light

Let's say we have a emitter, emitting light that has frequency f, less than the threshold frequency of a metal. If you leave light shining onto that metal, for long enough, does the energy of the ...
12
votes
4answers
1k views

Is photoelectric effect a surface phenomenon?

I got this question on a test and the answer key states that the answer is 'Yes'. According to what I understand electrons are emmitted with different kinetic energies based upon their depth from the ...
11
votes
2answers
17k views

What's the difference between the work function and ionisation energy?

In a particular textbook, the work function of a metal (in the context of the photoelectric effect) is defined as: the minimum amount of energy necessary to remove a free electron from the surface ...
10
votes
1answer
802 views

How is the Photoelectric Effect affected by Blue-Shifting

I was thinking about the Photoelectric Effect and Blue-Shifting when I came up with a thought experiment that I couldn't think of an answer for. The thought experiment is as follows: A metal plate is ...
9
votes
2answers
2k views

Why does classical physics imply every mode of vibration should have the same thermal energy?

I've just started reading about photo electric effect here, and my high school level understanding goes something like this : 1) By 1900 we had Maxwell equations and treated light as a wave. 2) But ...
9
votes
2answers
836 views

Does Quantum Theory allow an Electron to take a fraction of Photon energy

In Photoelectric Effect of Theory of Spectral Lines , an electron takes the entire or none of the energy of the Photon ( it absorbs the entire quanta not its fractionS resulting in the disappearance ...
9
votes
4answers
34k views

What is the relation between photoelectric current and frequency of incident light?

I googled it a bit and found that photoelectric current is independent of frequency(of incident light). Some further look revealed that actually "saturation current" is independent of frequency.I ...
8
votes
6answers
38k views

In the famous Einstein's Photoelectric effect, why does the intensity of light not raise the kinetic energy of the emitted electrons?

The work function of any metal is no doubt constant for it is related to electromagnetic attraction between electrons and protons. However on increasing the intensity of any light source the kinetic ...
8
votes
4answers
104k views

Stopping potential in the photoelectric effect, collector work function

In this question I am talking about the following situation: Now, I know that the max kinetic energy of the electrons emitted is $KE_{max} = h\nu - e\phi_{em}$ where $\phi_{em}$ is the work ...
8
votes
4answers
3k views

Why do electrons move towards anode in the Photoelectric effect experiment?

Consider a Photoelectric effect experiment apparatus as shown in Figure 11.1 The variation of photocurrent with the voltage applied across $\mathrm{A}$ and $\mathrm{C}$ is as shown in Figure 11.3. ...
8
votes
2answers
3k views

Does Tesla's photoelectric “solar cell” really work?

Tesla patented a device for gathering energy from light, using the photoelectric effect. (US 685,957 - Apparatus for the Utilization of Radiant Energy): Basically just a sheet of "highly polished or ...
7
votes
5answers
22k views

Saturation current in photoelectric effect

While studying photoelectric in my school, my teacher drew a graph of current versus the potential difference across the two electrodes: I am not able to understand why do we get saturation current. ...
7
votes
2answers
3k views

Does the photoelectric effect obey Ohm's law?

I've been reading about the photoelectric effect for my modern physics class, and I was confused about how Ohm's law works in relation to it. Let's say we have a photoelectric apparatus that simply ...
7
votes
3answers
2k views

What if all the electrons leave a metal?

I was studying photoelectric effect. Then I thought that what will happen if all the electrons from a metal piece come out as photoelectrons by using a light source of particular frequency? Will the ...
7
votes
1answer
4k views

Photoelectric effect – Why does one electron absorb one photon?

When I read about the photoelectric effect, I came across this: "The electrons could not absorb more than one photon to escape from the surface, they could not therefore absorb one quanta and then ...
7
votes
3answers
11k views

Why do electrons in an atom 'fall' back to the ground state?

Why, after absorbing a photon does an atom's electron 'fall' back to its ground state (what causes it to immediately lose its absorbed energy)?
7
votes
2answers
1k views

Is there a way to calculate the photoelectric effect in QED via a Feynman diagram?

The photoelectric effect is the historic origin of the quantum particle description of light. From it we learn that when light is shone onto a metal single photons interact with single electrons in ...
6
votes
1answer
676 views

How is a CCD able to collect images in drastically different lighting conditions?

I have read the basics of how a digital camera works. As much as I have understood, the digital cameras have a device called a CCD on which photons coming from the lens are incident. The CCD then ...
5
votes
3answers
912 views

What's the lifetime of the excited state when you shine light on molecules?

Let's say, when x-ray hits a molecule, an electron from an inner shell absorbs the energy and flies away, so there's a hole waiting for an electron to come down and fill it. How long does this hole ...
5
votes
2answers
35k views

What happens to the absorbed light energy?

When light comes across with a solid material, some of it is reflected, some of it passes through and some of it is absorbed. I understand the reflection and passing through, but I don't understand ...
5
votes
3answers
727 views

Does electron absorb energy? [closed]

According to my teacher, an electron is point sized and it does not absorb or release energy. Moreover, my teacher says their orbital absorbs energy rather than the electron. If that is the case, then ...
5
votes
2answers
2k views

Why are photoelectrons emitted in the direction of incident photons?

In the experiments for photoelectric emission, the light is incident on one face of the emitting plate, for example the anode, when determining the stopping potential. The electrons are emitted by ...
5
votes
3answers
236 views

Which particle aspect is required to explain photoelectric or Compton effect?

What do we mean when we say that it requires the particle nature of radiation i.e., photons, to explain photoelectric or Compton effect? I don't understand which particle nature is used to explain ...
5
votes
1answer
414 views

Photoelectric effect: Experimental Physics

Suppose you are doing an experiment to determine the work function of a metal.  You get $KE_1$, $\nu_1$ and $KE_2$, $\nu_2$.   We know that $KE = h\nu - W$ but when you solve the simultaneous ...
5
votes
2answers
372 views

Why is there an upper energy limit on the photoelectric effect? [duplicate]

I feel like I'm missing something really fundamental regarding the cross section of the photoelectric effect. I'm looking at this chart, and it seems that the lower the energy of the incident photon, ...
5
votes
4answers
3k views

Why is the K shell electron preferred in the photo electric effect?

I have read in many books and on Internet as well that photoelectric effect is only possible when an electron is emitted from the K shell of the metal. Why not other bonded electrons?
5
votes
4answers
12k views

Kinetic energy and Potential of a photon

How does the potential and kinetic energy of a photon relate? Do they mean the same thing? Also how does De broglie wavelength and Potential relate?
4
votes
4answers
2k views

Why is Maxwell's theory insufficient to explain the photoelectric effect?

You can argue that electromagnetic waves from a UV light source travel towards a metallic plate, and by the time they reach where a loose electron is located, they affect it with a electromagnetic ...
4
votes
3answers
1k views

Photoelectric effect absorption coefficient decreases with energy, why?

Consider the diagram below: (Author: Joshua Hykes source: Wikipedia) From this diagram we can see that the absorption coefficient for the photoelectric effect generically decreases with the increase ...
4
votes
4answers
2k views

So why are photoelectric panels flat?

In this post Why not use our own light production to produce new energy instead of wasting it?, I naively asked if it was possible to also recycle our own lightning at night. someone, in his answer, ...
4
votes
1answer
724 views

Classical (or semi-classical) interpretation of photoelectric effect?

This site says that "it has recently been proven that the photoelectric effect can be interpreted classically (or at least semi-classically) in non-particle, wavelike terms". Is anyone familiar with ...
4
votes
3answers
4k views

Photoelectric effect: Why is the saturation current the same, as you vary the frequency of incident light but keep its intensity constant?

image courtesy of http://www.learncbse.in/ Why is the saturation current the same, as you vary the frequency of incident light but keep its intensity constant? If intensity is a measure of the ...
4
votes
2answers
605 views

Kinetic energy of photoelectrons

I came across the following question: A photon of energy $h\nu$ is absorbed by a free electron of a metal having work function $W<h\nu$. Then: The electron is sure to come out The ...
4
votes
2answers
1k views

Photoelectric effect stopping potential

$q_eV_s = hf - \phi$ My question is... suppose we are testing the photoelectric effect. One plate is illuminated. We have applied the stopping potential. Suppose an electron leaves one plate with $KE ...
4
votes
1answer
591 views

Why don't metals disintergrate in light?

I've been learning about photoelectricity. An electron can gain the energy from a single photon, and if that energy is greater than the work function of the metal the electron can leave the metal. ...
4
votes
1answer
51 views

Is Einstein's Photoelectric effect a reversible phenomenon?

If one emits a light beam in a given frequency (obviously there is a threshold frequency) over a metal plate, even on low energies, some electrons could be ejected and one could been measuring an ...
4
votes
1answer
99 views

Classical wave energy vs Photon energy

The classical theory says that the intensity of light is proportional to the square of the amplitude of an oscillating electric field. Quantum theory gives the intensity of light as proportional to ...
4
votes
1answer
1k views

Is a vacuum needed in photoelectric effect?

This question was asked to me. My first thought was that electrons may ionise the air and potential difference that was applied may increase or decrease the current which should have been observed. ...
4
votes
1answer
24k views

How to find the work function of a metal without knowing the threshold-frequency?

As the title says it, I want to know how people find the work function of a metal without knowing the threshold frequency. Yes I've already searched on Google but I didn't find anything really ...
4
votes
1answer
148 views

Electrons motion

Some days ago, I was reading a very simple text about photoelectric phenomenon (at high school level) that this question came to mind. How do electrons move (for example during their translation from ...
4
votes
1answer
131 views

Why are there multiple L-edges in X-ray photoionization?

In heavier elements, why are there multiple L-edges in photoionization? In the image below, what do $\rm{L_{I}}$, $\rm{L_{II}}$ and $\rm{L_{III}}$ stand for? In this handout, (page 141 Figure 7.13), ...
4
votes
1answer
614 views

Is the photoelectric effect 'Ionising Radiation'?

According to the definition on Wikipedia, ionising radiation is radiation which has sufficient energy to remove an electron from an atom. So a high energy gamma ray is definitely ionising, but visible ...
4
votes
1answer
400 views

Photomagnetic effect

I just saw an article on wikipedia: http://en.wikipedia.org/wiki/Photomagnetic_effect "This article appears to contain unverifiable speculation and unjustified claims. Information must be verifiable ...
4
votes
0answers
189 views

What is the refractive index of an electron?

Consider a free electron or electron bunch, would it have a corresponding refractive index? At low or high energies, the effects are obviously much different. I am curious to know (I haven't found) ...