An electron experiences a downward force of 12.8×10-19 N while traveling in a magnetic field of 8×10-5 T west, what is the magnitude of the velocity?

Explanation:

Given that,

Magnetic force acting on an electron,

The magnitude of the magnetic field,

We need to find the magnitude of the velocity. We know that the magnetic force is given by :

Where

v is the velocity

So,

So, the magnitude of velocity is.

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west