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

Given are a uniform electric field, E = 30,000 V/m inside a capacitor (see picture), and a uniform magnetic filed, B = 10 T, perpendicular to the plane of the page, present in all of the area.

Identical charged particles are moving in a trajectory marked by the dashed line, under the influence of the two fields: The trajectory inside the capacitor is a straight line, and the trajectory outside the capacitor is circular, with radius r = 1 cm.

**What is the velocity v of the charged particles?**

**2. Relevant equations**

Possibly r = mv / qB , but I don’t know the mass of the particle.

Maybe E = F/q

**3. The attempt at a solution**

I know that the magnetic field is into the page based on the RHR. The particle is in circular motion because of the velocity and magnetic force vectors. The answer is v = 3000 m/s but I have no idea how it was derived.

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

**2. Relevant equations**

**3. The attempt at a solution**

http://ift.tt/1kpoETn