PROBLEM 45 & 46 May 21 2010

PROBLEM 45 & 46 May 21 2010 - 2 / E U m p . About...

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

View Full Document Right Arrow Icon
Solving Problems 45 and 46 Phys 002C May 21 2010 Problem 45. (Like Problem 28.34) The hydrogen 2P level decays with a 1.6 ns lifetime to the 1S level emitting Lyman radiation at 123 nm. What is the approximate line width of the Lyman radiation? (a) 1 nm; (b) 0.01 nm; (c) 0.00001 nm; (d) 0.1 nm; (e) 0.001 nm. What do you know?  / ) / ( ) / ( ) / ( ) ( / 2 hc hc hc h t h E So = (123 10 t c / 2 -9 ) 2 /(3 10 8 1.6 10 -9 )=3.15 10 -14 m = 3.15 10 -5 nm Problem 46. (Like Problem 28.49) The probability of a particle of energy E getting through a tunnel barrier of width and potential height U in a single try is x } 2 exp{ x , where 2 / ) (
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 2 / E U m p . About how many times would an electron of total energy E =1 eV have to hit a barrier of width =1 nm and height U = 2 eV, before tunneling through? Note, the electron mass is 0.91110 x -30 kg, 1 eV=1.60210-19 J and =1.05410-34 Js. (a) 1; (b) 86; (c) 2,500; (d) 28,000; (e) 64,000,000 What do you know? 2 . 10 10 054 . 1 / 10 6 . 1 10 911 . 2 10 2 / ) ( 2 2 2 34 19 30 9 2 Js J kg m E U m x x The number of tries would need to be exp{10.2} = 28,000....
View Full Document

Ask a homework question - tutors are online