In a television set, electrons are accelerated from rest through a potential difference of 18 kV. The electrons then pass through a 0.34 T magnetic field that deflects them to the appropriate spot on the screen. Find the magnitude of the maximum magnetic force that an electron can experience.

Question

In a television set, electrons are accelerated from rest through a potential difference of 18 kV. The electrons then pass through a 0.34 T magnetic field that deflects them to the appropriate spot on the screen. Find the magnitude of the maximum magnetic force that an electron can experience. 
I started by using F=Bqvsin theta. I tried to find the velocity by converting 18kV to Joules and using that in the .5mv^2 kinetic energy equation to find the velocity. I plugged in this velocity into the F=Bqv Sin theta equation to try to find the F but I am still getting this wrong. Could anyone tell me my mistake? Thanks!

I assume you are converting the electrical energy with the charge of one electron. 
1/2 m v^2= Vq 
solve for v.

Thence proceed as you stated.