# Electron enters uniform magnetic field and takes circular path

**1. The problem statement, all variables and given/known data**

A time t = 0 an electron enters a region of uniform magnetic field B = 0.010 T and has kinetic energy of 6.40E-16 J. It goes through a half-circle, exits the field and then accelerates across a gap with a potential difference of 2000 V, increasing in speed. It then hits a collecting cup. At what time t does it hit the cup?

**2. Relevant equations**

Δt=(1/2)T=(1/2)(2πm/|q|B)

x=v_{0}t+(1/2)at^{2}

**3. The attempt at a solution**

I can find the time to go through the half circle using the first equation above. It is 1.788E-9s. I need to find the time to get to the cup so I can add the two times up to get the total time.

http://ift.tt/1mEKNit

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