Calculating Electron Mass from Magnetic Field and Potential Difference

[invinc1ble]

I don't know if this is the place to post this, but This is a simple Grade 12 Physics question that I have been working on for about half an hour now.

For those who don't normally use this notation,
2E10 = 2X10^10.
2E-2 = 2X10^-2

"A magnetic field of 3.4E-3T deflects electrons into a circular path of radius .014m. The electorns have been accelerated through a potential differenc eof 250V. If the charge of an electron is 1.6E-19C, what is the mass of the electron?"

I have done it three times, and I keep getting 7.25E-31Kg when in actuality, a real electron is 9.11E-31Kg

 

[chroot]

Do you really mean 3,400 tesla? I doubt it.

- Warren

 

[invinc1ble]

sorry.. i'd make that 3.4E-3T
(.0034)

 

[chroot]

Well, I derived

$$m = \frac{B^2 q (2 r)^2}{8 V}$$

and got the same answer you got:

http://www.google.com/search?num=30...014)+meters)^2)+/+(8+*+250+volts)&btnG=Search

Are you sure the problem was copied down properly?

- Warren

 

[invinc1ble]

I did this question from a worksheet, and we both got identical answers.

If you have the same answer that my friend and I do, then chances are it is correct.

Thanks for your help!