Here you see an apparatus where charged particles from the source, at the left,
ID: 1634180 • Letter: H
Question
Here you see an apparatus where charged particles from the source, at the left, fly to the right and enter a space with crossed electric (E) and magnetic (B) fields. The upper plate has a positive charge and the lower one, a negative charge. The electric field between the plates points straight down the page, causing an electric force Fxd that pushes the moving charges straight down. The magnetic field, indicated by the Xs points straight into the page and produces a magnetic force, Fx straight up the page.1) What can you say about the charge on the particles flying from the source?
a) They must be negative
b) They must be positive
c) There's no way to know
2) The particle moving faster than those that fly straight through would
a) follow the same straight path; speed does not affect the direction
b) drift down the page toward the area marked by 2
c) drift up the page toward the area marked by 1
3) Which of these currently identifies one or more differences between electric and magnetic forces?
a) Electric forces point along field lines; magnetic forces point at a right angle to them
b) Electric forces do not depend on the particles speed, but magnetic forces do
c) voltage create electric fields but current create magnetic fields
d) all of these are correct
Explanation / Answer
(1) Charge must be positive because the electric field is acting downward. Therefore the force on the positive charge will be in downward direction. If the charge would be negative then the force will be upward.
hence the correct option is b.
(2) Magnetic force is directly proportional to the speed
F = qVB
hence on increasing the speed the net force will be in the upward direction which provide acceleration in the upward direction so it will be drift toward upper side.
hence the correct option is C.
(3) all statements are correct.