Problem

Uniform electric and magnetic fields with strength

E

and

B

are directed along the

y

-axis. A particle with specific charge

q/m

leaves the origin in the direction of

x

-axis with an initial velocity

v_0

. Find (a) the

y

-coordinate of the particle when it crosses the

y

-axis for

n

th time. (b) the angle

\alpha

between the particle's velocity vector and the

y

-axis at that moment.