# Ra milikans photoelectric experiments that supported einsteins theory

Today, the accepted value is 1. Working with Fletcher, Millikan showed that the charge of the droplets were always a whole number multiple of 1. Fortunately, these electrons aren't moving at relativistic speeds! The fact that 16 years went by before Einstein won a Nobel Prize for his ground-breaking work on the photoelectric effect, reflects how long it took the scientific world to accept that radiant energy is quantized.

I have in recent years been subjecting this experiment to some searching experimental tests from a variety of viewpoints, and have been led to the conclusion that, whatever its origin, it actually represents very accurately the behavior… of all the substances with which I have worked.

And while I wasn't annoyed enough to clear my schedule of more important day job stuff in order to respond in blog time, I do want to say something to highlight Millikan's other great work.

It is an extremely important and unjustly overlooked bit of work, though, which cleared up some controversies about earlier measurements, and played an important role in locking up the case for quantum theory. This was consistent with his hypothesis that the charge on the electron was the same as that found in hydrogen.

InMillikan wrote: Robert Millikan, the very man who showed that the equation really did work, would have nothing to do with its physical interpretation.

Some of the electrons would be shaken so hard, the theory went, that eventually they'd be tossed out altogether. If the body is charged to a positive potential V0 and is surrounded by conductors at zero potential, and if V0 is just large enough to prevent the loss of electricity, it follows that where e is the electronic charge All the light of a particular frequency comes in little bullets of the same energy, equal to the frequency multiplied by Planck's constantand that's the key to understanding the photoelectric effect.

In his mid-twenties Compton hatched a theory of the intensity of X-ray reflection from crystals that gave a powerful tool for studying the crystallographic arrangement of electrons and atoms in a substance.

The glass vessel shown below was evacuated; one of the metal samples mounted on the wheel W at the center was rotated to bring it next to the knife K, which scraped it clean; then the sample was rotated degrees to face light shining through aperture O.

Hertz found that by shining ultraviolet light onto metal electrodeshe could lower the voltage needed to make sparks hop between the electrodes. In this figure from Lenard's paper, the potential voltage is plotted on the horizontal axis, and the current on the vertical axis.

The key breakthrough came in and was published the following year. If, as physicists believed, the photoelectric effect followed from an interaction between electrons and electromagnetic waves, then intensifying the radiation ought to shake the electrons in the metal surface harder and so shoot them out with more energy.

This seems like it ought to be easy to explain, but classical physics turned out not to do a very good job of it, as I explained back in the pre-ScienceBlogs days of this blog. Yet, incredibly, Einstein never won a Nobel Prize for relativity. One of the great improvements was the use of oil drops instead of the cloud of water drops that Thomson used.

Yet the semi-corpuscular theory by which Einstein arrived at his equation seems at present to be wholly untenable. Light from source L shines onto plate U. Hertz was creating and detecting waves using spark gaps-- discharging a current through a small gap to make a spark in the air produced a blast of radiation, which he then detected by its ability to trigger a spark between another pair of electrodes some distance away.

As Einstein said in"There are Robert Millikan, the very man who showed that the equation really did work, would have nothing to do with its physical interpretation. In the conclusion of the March paper, he opens by saying: Kadisch, and he thanks Walter Whitney for doing spectroscopy to determine the wavelengths of light from his source.

He also used optical filters to eliminate the effects of stray light at wavelengths other than the one he was trying to test-- a precaution that anybody who's ever tried this in a modern physics course can tell you is absolutely essential-- and investigated the effects of contacts between the metal being studied and the different wires used to connect to the measuring apparatus in great detail.

NO electrons are produced if the frequency of the light waves is below a critical value. Having established that the model worked, Millikan then put it to use, in the March paper.

By modern standards, those people would probably be co-authors. Contributors Overview Although Hertz discovered the photoelectron init was not until that a theory was proposed that explained the effect completely. Thus, only electrons ejected with enough kinetic energy to get up this potential hill would contribute to the current.

Experimentalists railed at the prospect of what Einstein's equation of the photoelectric effect implied. Light could manifest itself as particles. I have in recent years been subjecting this experiment to some searching experimental tests from a variety of viewpoints, and have been led to the conclusion that, whatever its origin, it actually represents very accurately the behavior… of all the substances with which I have worked.Foremost among them was the photoelectric effect: the ejection of electrons from a metal when irradiated by light.

The wave theory of light could not yield a satisfactory account of this, since the energy of a wave is spread over its entire surface. Dec 17,  · Einstein’s theory of photoelectric effect. Photoelectric effect: The process in which visible light, x rays, or gamma rays incident on matter cause an electron to be ejected.

The ejected electron is called a photoelectron. This led to the two papers above, and contributed to Nobel Prizes for both Einstein (the photoelectric effect is the only specific theory mentioned in his prize citation) and Millikan. What was measured in Millikan's study of the photoelectric effect?

David R. Lloyd Citation: American Journal of Physics 83, (); doi: / unambiguous experimental support for Einstein’s theory of the photoelectric effect. His graphical about what Millikan’s experiment does.

Although Millikan’s.

Einstein's simple explanation (Equation \ref{Eq1}) completely accounted for the observed phenomena in Lenard's and Millikan's experiments (Figure $$\PageIndex{4}$$) and began an investigation into the field we now call quantum mechanics.

This new field seeks to provide a quantum explanation for classical mechanics and create a more unified theory of physics and thermodynamics. The photoelectric effect posed a significant challenge to the study of optics in the latter portion of the s.

It challenged the classical wave theory of light, which was the prevailing theory of the time. It was the solution to this physics dilemma that catapulted Einstein into prominence in the physics community, ultimately earning him the Nobel Prize.

Ra milikans photoelectric experiments that supported einsteins theory
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