PHOTO ELECTRIC EFFECT

Photon | Introduction to Photo Electric Exepriment

Heating Effect Of Electric Current

In photo electric effect, if the energy required to over come the attractive forces on the electron (work function) of Li, Na and Rb are 2.41eV, 2.3eV and 2.09eV respectively, the work function of ''K'' could approximately by in eV

Which of the following is correct regarding photo-electric effect? (i) The photo-electric effect takes place if lambda le lambda_(0) or upsilon ge upsilon_(0) . maximum K.E. of photo-electron K_(max) =hv=(hc)/(lambda) Einstein photo-electric effect equation hv=hv_(0) + K_(max) (ii) The maximum K.E. of electron or stopping potential V_(s)(K_(max) =eV_(s)) for a given metal depends only on frequency or wavelength of incident light and not on its intensity (iii) The saturation current (i =ne, n: number of photo-electrons ejected per unit time) depends on intensity and not frequency (iv) Normally it is assumed that one photon eject one electron. Practically several incident photons eject one electron. If quantum efficiency is given {"Quantum efficiency" =("Number of electrons ejected")/("Number of photons incident")} Number of electrons ejected must be calculated must be calculated and then calculate saturation current

An orbiting satellite can become charged by the photo- electric effect when sunlight ejects electrons from its outer surface. Satellites must be designed to minimize such charging because it can ruin the sensitive microelectronics. Suppose a satellite is coated with platinum, a metal with a very large work function (Phi= 5.32 eV) . Find the longest wavelength of incident sunlight that can eject an electron from the platinum.

Yellow light of 557 nm wavelength is incident on a cesium surface. It is found that no photo electrons flow in the circuit when the cathode-anode voltage drops below 0.25V. Then the threshold wavelength for photo electric effect from cesium is

Which of the following is correct regarding Einstein photo-electric effect equation? (i) The equation is hv =hv_(0) + K_(max) =hv_(0)+ eV_(s) (ii) The variation of V_(s) with v is (iii) The variation of photo-current versus applied potential (iv)

In an experiment on the photo-electric effect Singly ionized helium is excited electronically to different energy levels. The light emitted by ionised helium is incident on photo-electric plate in a photocell. When helium is excited to fourth energy level, then the observed stopping potential of the photocell is found to be five times the stopping potential measured when the photoelectrons are produced by using light emitted by hydrogen atom, excited to the third energy level. Determine the work function of the material of the photo-electric plate.