Consider the motion of a positive point charge in simultaneous uniform electric and…

PHYSICS · Multi correct · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism

Problem

Consider the motion of a positive point charge in simultaneous uniform electric and magnetic fields

\mathbf E=E_0\hat{\mathbf j}

and

\mathbf B=B_0\hat{\mathbf j}

. At time

t=0

, the charge has velocity

\mathbf v

in the

xy

-plane, making an angle

\theta

with the

x

-axis. Which option(s) are correct for

t>0

? (1) (a) If

\theta=0^\circ

, the charge moves in a circular path in the

xz

-plane. (2) (b) If

\theta=0^\circ

, the charge undergoes helical motion with constant pitch along the

y

-axis. (3) (c) If

\theta=10^\circ

, the charge undergoes helical motion with its pitch increasing with time along the

y

-axis. (4) (d) If

\theta=90^\circ

, the charge undergoes linear but accelerated motion along the

y

-axis.