Determine the direction of the force that will act on the charge in each of the following situations. A positive charge moving to the right in a magnetic field that points out of the screen. A positive charge moving to the right in an electric field that points out of the screen. A negative charge moving out of the screen in a magnetic field that points into the screen.

a) the force goes down, b) The electric force is out of the screen

c) the force is zero

Explanation:

To determine the direction of a magnetic force we use the right hand rule. For a positive charge, the thumb is in the direction of speed, the fingers extended in the direction of the magnetic field, and the palm points in the direction of force. Let's apply this to our case

a) thumb   to the right

 Fingers spread out

And the force goes down

b) the electric force in the direction of the electric field if the charge is positive

 Positive charge

Electric field out of the screen

The electric force is out of the screen

c) charge moving out screen

   Magnetic field entered on the screen

Since they are parallel, therefore the force is zero