Physics 19 – Photoelectric Effect. Overview: In , Heinrich Hertz discovered that when electromagnetic radiation shines on a clean, metal surface, electrons. PDF | The photoelectric effect is commonly used as the introductory topic for the study of quantum physics. However, a literature review reveals. Photoelectric effect: experiment showing light is also a particle. Energy comes in particle-like chunks- basics of quantum physics. (energy of one chunk depends.
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Photoelectric effect. 1 Background. A photon of frequency ν carries energy hν, where h is Planck's constant. If such a photon strikes an electron inside a metallic . Experimental Set-up to study Photoelectric Effect. 4. Effect of Intensity, Frequency, Potential on P.E. Current. 5. Graphical representation of variation of P.E. Albert Einstein ( - ) published his theory of the photoelectric effect in , the same year in which he published the Special Theory of.
When we see one particle we believe that have a direct connection with it. But how I can see the particle? I propose one medium, the Ether.
This name is used by many scientists; the difference is how interpreting it. When definite a position we use electromagnetic wave. Ii is valid only when we can measure without change the original position.
The theory said that the current is cero. Is it possible talk the wave replace the particle.
Would be possible the electron wave replace the electron particle? We must focus in the photoelectric cell. The electrons go to anode to cathode, not problem. But if we suppose that I could find one light frequency to the anode and I could generate electric current?
The experimental physics says us that gamma ray could generate positrons. Why not probe illuminates the cathode with gamma rays? Of course, we must probe some material like a different metals or non-conductors to find the positronic current. If an Ether hypothesis is correct I think other experiment is possible. When we talk about Ether it is the medium where the electromagnetic phenomena propagate.
The current has electromagnetic nature then the Ether is involved. Many electromagnetic wave surrounding the photoelectric cell. How make it?
Photoelectric effect was discovered by Hallwachs, experimentally verified by Hertz, and successfully studied and explained by Einstein. Less energy is required to release the electrons situated in the surface layer of material where as more energy is required to release electrons from the inner layers.
Stopping potential does not depend on the intensity of incident light. Intensity of light is related to amount of photons and in more simplified terms it is related to no. But frequency of light directly indicates toward energy of one photon. A If intensity in case 1 is higher so no. Work function is the characteristic of matter. One photon can emit only one electron. The whole photo electric effect is based on this simple concept. If light of same frequency incidences on surfaces of various work function then velocity or kinetic energy of that emitted electron will be maximum for which surface that has least work function.
Two different photons of energies, 1 eV and 2. Stopping potential will be A 1. Find the wavelength of light. The work functions of sodium and copper are respectively 2. To eject photo-electrons from sodium the longest wavelength is and that for copper is Hence for light of wavelength , sodium is suitable.
The work function for the surface of aluminium is 4. What will be the wavelength of that incident light for which the stopping potential will be zero. A B m C D If the incident light be of threshold wavelength 0 , then the stopping potential shall be zero. A radio station is transmitting waves of wavelength m, If diffracting power of transmitter is 10 kw, then numbers of photons diffracted per second is A 1.
To stop emission of photo electron, retarding potential required to be A 3.
Light of wavelength falls on a sensitive surface. If the surface has received Joule of energy, then what is the number of photons falling on the surface? Find out the maximum velocity of the photo electrons emitted by the surface A Calculate its energy. If work function for aluminium surface is 4. If light of wavelength is used then stopping potential would be A 2. If wavelength changes to 2 then stopping potential becomes V0.
If it is placed at 4 m distant, then value of stopping potential becomes A 2 volt B 1 volt C 4 volt D 16 volt Sol Stopping potential does not depend upon distance from light source.
These electrons are attracted by the anode A and so a current flows in the external circuit. Photoemissive cells are used in exposure meters, cinematography, etc.
This layer is covered with a thin film of silver or gold which is practically transparent. When light falls on the oxide layer move towards the silver film. Then silver film becomes negatively charged and the metal base becomes positively charged. The voltage across the resistance R is proportional to the intensity of light. Photovoltaic cells are used in light meters, exposure meters, etc. The cell consists a semiconductor material like selenium or lead sulphide provided with two electrons.
When light is incident on the cell its resistance decreases and conductivity increases.
Hence the current in the battery circuit containing photoconductive cell changes with change in intensity of light with a time lag.