Question

Assume that a uniform magnetic field is directed into thispage. If an electron is released with an initial velocity directedfrom the bottom edge to the top edge of the page, which of thefollowing describes the direction of the resultant force acting onthe electron?

A. out of the page
B. to the right
C. to the left
D. into the page

Answer 1

Answer:

B). to the right

Explanation:

Since the direction of magnetic field is into the page

So here we know that

$B = B_o(-\hat k)$

now the velocity is from bottom to top

so we have

$v = v_o \hat j$

now the force on the moving charge is given as

$\vec F = q(\vec v \times \vec B)$

now we have

$\vec F = (-e)(v_o \hat j \times B_o(-\hat k))$

$\vec F = e v_o B \hat i$

so force will be towards Right