Determine the direction of the force if any that will act on

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

Solution

(a)

the force is opposite to the field direction when the charge is negative.

therefore, the force points to the left.

(b)

the force is in same direction to the field direction when the charge is positive.

therefore, the force is directed in upward.

(c)

to the right (From Flemins left hand rule and charge is negetive so direction reverses)

(d)

From Flemins left hand rule, the force is in downward when the field points out of the screen and charge moving to the right.

(e)

the force is opposite to the field direction when the charge is negative.

therefore, the force points into the screen.

(f)

here, charge is positive, and its move into the screen, and also field is into the screen

So, v and B are in same direction. vxB = 0, vector multiplication of two vectors in same

direction yeilds magnitude of 0 So, there is zero force.