A negative charge (−q) is moving in the +x direction when it encounters a region of constant magnetic field pointing in the −y direction. Which is the direction of the initial net force on the charge?
+y
−y
+z
−z
???
Grade Distribution
Magnetostatics
A proton (q=+e) is released from rest in a uniform E and uniform B. E points up, B points into the page. Which of the paths will the proton initially follow?
A + charged particle moving up (speed v) enters a region with uniform B (left) and uniform E (into page). What's the direction of Fnet on the particle, at the instant it enters the region?
To the left
Into the page
Out of the page
No net force
Not enough information
A proton (speed v) enters a region of uniform B. v makes an angle θ with B. What is the subsequent path of the proton?
Helical
Straight line
Circular motion, ⊥ to page. (plane of circle is ⊥ to B)
Circular motion, ⊥ to page. (plane of circle at angle θ w.r.t. B)
Impossible. v should always be ⊥ to B
A negative charge (−q) is moving in the +x direction when it encounters a region of constant magnetic field pointing in the −y direction. Which is the direction of the initial net force on the charge?
+y−y+z−z
???
CORRECT ANSWER: C
Make sure to take into account the sign change
