Problem 18.46 What is the ratio of the radii of their circular paths? R235/R238=
ID: 1773711 • Letter: P
Question
Problem 18.46 What is the ratio of the radii of their circular paths? R235/R238= 0.987 Submit My Answers Give Up Correct A mass spectrometer is used to separate the uranium isotopes 235U and 238U. Part B In this spectrometer, singly ionized uranium ions pass first through a 140 m/s velocity selector, and then into a 2.60 T magnetic field. Find the diameter of the an traced out by the 35U isotope Express your answer with the appropriate units ? Das 1.32-104 m Submit My Answers Give Up Incorrect; Try Again; 3 attempts remaining Part C Find the diameter of the arc traced out by the 2U isotope. Express your answer with the appropriate units D8.83-10 m Submit My Answers Glve Up ncorrect; Try Again; 6 attempts remainingExplanation / Answer
1. R = mv/Bz ...............[1]
Assuming the ions are the same, then the ratio of your two radii will be simply the ratio of the masses.
For example, U-238 radius will be 238/235 of the radius for U-235.
2. m = 9.1 * 10^-31 * 235 (kg) = ..........[2];
v = 140 (m/s); B= 2.6 (T); z = 1.602 * 10^-19 (C) ................[3]
Therefore R = 2.1385 * 10^-28 * 140/(2.6 * 1.602 * 10^-19) = 7.2 * 10^-8 m or approximately 72 nm.
The diameter will be double the radius or about 144 nm.
3. Based on the ratios in 1, the diameter will be 238/235 * 144 nm ~ 145.8 nm
Hopefully it's of some help.