Question

1.

A straight current-carrying wire in a uniform magnetic field experiences a magnetic force

a		only if the wire is moving.
b		only if the wire is parallel to the field.
c		parallel to the wire.
d		perpendicular to the wire.

2.

Magnetic field strength is greater

a		where the field lines are closer together.
b		where the field lines are further apart.
c		where the field lines are evenly spaced.
d		where the field lines cross.

3.

A moving, charged particle in a uniform magnetic field will NOT experience a magnetic force

a		if it moves parallel to the field lines.
b		if it moves perpendicular to the field lines.
c		if it moves around the field lines in circles.
d		None of the above.

4.

If a straight wire carries a 2.00-A current perpendicular to a uniform, 0.125-T magnetic field for 3.50 cm, the force on the wire will be

a		zero.
b		8.75x10-3 N.
c		0.875 N.
d		87.5 N.

Answer 1

1. (d) Perpendicular to the wire (by F = ILB sin and Fleming's left hand rule)

2. (a) where the field lines closer together (closer field lines shows magnetic field strength is greater)

3. (a) if it moves parallel to the lines (by F = q v B sin, if =0 then F =0 N)

4. (b) 8.75 x 10-3 N   (by F = ILB sin = 2 x 3.5 x 10-2 x 0.125 = 8.75 x 10-3 N)