# Thread: Another Question on 3-d vectors

1. ## Another Question on 3-d vectors

The electron beam that forms the picture in an old-style cathode ray tube TV is controlled by electric and magnetic forces in three dimensions. Suppose that a forward force of 5 femtonewtons is exerted to accelerate an electron in a beam. The electronics engineer wants to divert the beam 30 degrees left and 20 degrees upward. Determine the magnitude of the
a) component of the force to the left.
b) upward component of the force.
c) resultant force acting on the electron.

For a, 5 tan 30 yield the answer but I cant explain why.

2. Originally Posted by dalbir4444
The electron beam that forms the picture in an old-style cathode ray tube TV is controlled by electric and magnetic forces in three dimensions. Suppose that a forward force of 5 femtonewtons is exerted to accelerate an electron in a beam. The electronics engineer wants to divert the beam 30 degrees left and 20 degrees upward. Determine the magnitude of the
a) component of the force to the left.
b) upward component of the force.
c) resultant force acting on the electron.

For a, 5 tan 30 yield the answer but I cant explain why.
Consider the diagram below. We are looking down at the beam. The "forward" force is F = 5 fN and the force required to deflect the beam at 30 degrees is L.

So what is is L?

-Dan