Mass-to-Charge Ratio of an Ion in Mass Spectrometer

[camel-man]

Homework Statement

Consider fields of 1.4e5 N/C and 2.7 T within a velocity selector. If the charge then exits and encounters a field of 1.4 T and radius of 2.4 mm within the mass spectrometer, what would be the mass to charge ratio of this ion?

Homework Equations

v = E/B
m = qrB/V[/B]

q = 1.6 x 10 ^-19C
r = 2.4 x 10^-3 m
B = 1.4 T

The Attempt at a Solution

I got 51851 m/s for v

and my answer came out way off when I plugged it in for m.

I have the answer but when I try to do it myself. I get the wrong answer.

 

[BvU]

The exercise asks for m/q, not for m. What did you get ?
And what exactly do you mean when you say 'I get the wrong answer' ?

By the way: you got 5.2 x 10⁴ m/s, not 51851 m/s : you can't achieve five digit accuracy when all you're given is two digit numbers! But v wasn't wanted.
(However, when you work out this exercise with the given numbers in the expression for m/q, you do end up to within 1 promille of m/q of a known particle...what a coincidence!)