PROBLEM 41 & 42 May 18 2010

PROBLEM 41 & 42 May 18 2010 - o a m e c 2 b m e c...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Solving Problems 41 and 42 Physics 002C May 18, 2010 Problem 41. (Like problem 28.13) What is the maximum current that would be emitted from a copper surface (work function = 4.70 eV) illuminated by 1 W of 243 nm light? a) 0.2 A; b) 0.4 A; c) 0.6 A; d) 0.8 A; e) 1.0 A. What do you know? The number of photons per second is 19 1 6 19 6 10 6 . 1 1 7 . 4 1 / 10 6 . 1 1 7 . 4 1 s eV J eV W dt dN . Each photon releases at most 1 electron of charge e = 1.6 10 -19 C. The maximum current is then A s C s C dt dN e 2 . 0 7 . 4 1 10 6 . 1 1 7 . 4 1 10 6 . 1 6 19 1 6 19 . Problem 42. (Like problem 28.15) What is the energy of an annihilation photon [energy equal to m e c 2 ] after Compton scattering twice through 90
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: o ? a) m e c 2 ; b) m e c 2 /2; c) m e c 2 /3; d) m e c 2 /4; e) m e c 2 /5. What do you know? An annihilation photon (from electron-positron pair annihilation) has a wavelength equal to the Compton wavelength. After scattering the first time the wavelength is C C C 2 ) cos 1 ( ' . After the second scattering the wavelength is C C C C C 3 2 ) cos 1 ( 2 ' . The final energy is 2 3 1 3 1 3 ' mc hc hc hc C C ....
View Full Document

This note was uploaded on 09/23/2010 for the course PH 02c taught by Professor Mile during the Spring '04 term at Riverside Community College.

Ask a homework question - tutors are online