Question

Find the direction of the force on a negative charge for eachdiagram shown in Fig. 20-51, where v (green) isthe velocity of the charge and B (blue) is thedirection of the magnetic field. ( means the vector points inward. means it points outward, toward you.)

Figure 20-51

(a)---Select---to the leftto the rightupwarddownwardinto the pageout of the pageThe force is zero.

(b)---Select---to the leftto the rightupwarddownwardinto the pageout of the pageThe force is zero.

(c)---Select---to the leftto the rightupwarddownwardinto the pageout of the pageThe force is zero.

(d)---Select---to the leftto the rightupwarddownwardinto the pageout of the pageThe force is zero.

(e)---Select---to the leftto the rightupwarddownwardinto the pageout of the pageThe force is zero.

(f)---Select---to the leftto the rightupwarddownwardinto the pageout of the pageThe force is zero.

Answer 1

use right-hand rule (fingers in direction of v, curl them towardsB, thumb points in F) and then change the direction of F toopposite what you get (alternatively, use your left hand)

(a)   left
(b)   left
(c)   up
(d)   into page
(e)   zero
(f)   down