Question

A charged particle is moving perpendicularly to a magnetic field B. Fill in the blank indicating the direction for the quantity missing in each option. Use the diagram above for the directions of the various axes.

Answer 1

Force is given by

F = q(V x B)

1)

F = - k

q = - e

V = - i

B = ??

- k = - e(- i x B)

here B should be (- j) because i x j = k

direction of B = - y

2)

- k = - e (V x j)

V should be (i)

direction of V = + x

F = +e (- k x j)

we know k x j = - i

then F = i

direction of F is + x