The minimum frequency of light needed to eject electrons from a metal is called the threshold frequency, ?0. Find the minimum energy needed to eject electrons from a metal with a threshold frequency of 2.92×10^14 s^−1. ?0= With what maximum kinetic energy will electrons be ejected when this metal is exposed to light with a wavelength of 235 nm? ??electron=

The minimum frequency of light needed to eject electrons from a metal is called the threshold frequency, ?0. Find the minimum energy needed to eject electrons from a metal with a threshold frequency of 2.92×10^14 s^−1. ?0= With what maximum kinetic energy will electrons be ejected when this metal is exposed to light with a wavelength of 235 nm? ??electron=

Glencoe Physics: Principles and Problems, Student Edition

1st Edition

ISBN:9780078807213

Author:Paul W. Zitzewitz

Publisher:Paul W. Zitzewitz

Chapter27: Quantum Theory

Section: Chapter Questions

Problem 67A

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Similar questions

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A Thomson-type experiment with relativistic electrons. One of the earliest experiments to show that p = mv (rather than p = mv) was that of Neumann. [G. Neumann, Ann. Physik 45:529 (1914)]. The apparatus shown in Figure P4.5 is identical to Thomsons except that the source of high-speed electrons is a radioactive radium source and the magnetic field B is arranged to act on the electron over its entire trajectory from source to detector. The combined electric and magnetic fields act as a velocity selector, only passing electrons with speed v, where v = V/Bd (Equation 4.6), while in the region where there is only a magnetic field the electron moves in a circle of radius r, with r given by p = Bre. This latter region (E = 0, B = constant) acts as a momentum selector because electrons with larger momenta have paths with larger radii. (a) Show that the radius of the circle described by the electron is given by r = (l2 + y2)/2y. (b) Typical values for the Neumann experiment were d = 2.51 104 m, B = 0.0177 T, and l = 0.0247 m. For V = 1060 V, y, the most critical value, was measured to be 0.0024 0.0005 m. Show that these values disagree with the y value calculated from p = mv but agree with the y value calculated from p = mv within experimental error. (Hint: Find v from Equation 4.6, use mv = Bre or mv = Bre to find r, and use r to find y.) Figure P4.5 The Neumann apparatus.
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