What Determines the Speed and Frequency of an Electron in a Magnetic Field?

[missyc8]

Homework Statement

An electron with kinetic energy 1.92 keV circles in a plane perpendicular to a uniform magnetic field. The orbit radius is 26.0 cm.
Find the speed of the electron.

Find the magnetic field.

Find the frequency of circling. (Hz)

Find the period of the motion.

Homework Equations

v=sqrt(2*(3.7E-16J/9.109E-31)
k=(mv)^2/2
B-mvqr

The Attempt at a Solution

for velocity i get 2.85E-23 m/s ...but it is wrong...i do not know what to do

 

[willem2]

The Attempt at a Solution

for velocity i get 2.85E-23 m/s ...but it is wrong...i do not know what to do

try computing sqrt(2*(3.7E-16J/9.109E-31)) again