Question

Bo, in x X x X / X X X X Schematic diagram of a mass spectrometer is shown in the figure. It has two components the velocity selector and a chamber where only magnetic field is applied to make the particle go on a circular path. X X x X x X X + ----- * X + Detector *+ * * * Detector Useful Equations: array X + * X *- I T 1 02 X X + FB Fe =qE Fb = qvBsine & TY Fe X Velocity selector +

a) Mark the forces acting on the charge particle when it is in the velocity selector region and mention the cause for each force in the space below.

b) What condition should be satisfied if you want the particle to be not deflected in the velocity selector?

c) From the above condition obtain an expression for the velocity that is selected.

d) If this particle enters perpendicular to the magnetic field in the second chamber using the knowledge of circular motion and centripetal acceleration obtain the expression for radius of the path in terms of the magnetic field, charge, mass and velocity.

e) Substitute the velocity that you obtained in part c in the above expression and obtain an expression for q/m ratio.

f) If the B = 0.025T, E = 2.5 x 10^3 V/m, Bo = 0.035T and the particle hits the chamber at distance 2r = 50 cm. What will be the charge/mass ratio?

Answer 1

o creste FB=Fe qVB-AE qVB or mu? = r = mv a Bo ME 2 BB als 2.50103 - 25 x .0258.035 as Loys 1.14 x 10?