Question

A positive charge is moving across a room from south to north. A magnetic field runs from east to west. In what direction is the magnetic force on the moving positive charge?
toward the east

toward the west

toward the west

toward the ceiling

Answer 1

Answer:

Toward the ceiling

Explanation:

The direction of the magnetic force acting on a charged particle is given by using the right-hand rule. According to this rule, the thumb, the index finger and the middle finger of the right hand are held perpendicular to each other. The index finger shows the direction of motion of the charge, the middle finger points in the direction of the magnetic field and the thumb gives the magnetic force.

Here, the motion of the charge is from south to north. The magnetic field acting on it runs from east to west. So, using right-hand rule, the direction of magnetic force is toward the ceiling.

$F=q(v\times B)$

$F=q(J\times (-i))$

F = + Fk (toward the ceiling)

Answer 2

Answer:

toward the ceiling

Explanation:

In order to determine the direction of the magnetic force on the charge, we should use the right-hand rule. Putting the thumb, the index finger and the middle finger of the right hand perpendicular to each other, we have: (for a positive charge)

- The index finger corresponds to the direction of motion of the charge (in this case, toward north)

- The middle finger corresponds to the direction of the magnetic field (in this case, towards west)

- The thumb will give us the direction of the magnetic force --> in this case, the thumb points towards the ceiling, so the direction of the magnetic force is towards the ceiling.