Magnetic fields and forces

Question 1

Which of the following is FALSE concerning the properties of magnetic field lines?
The field lines cannot cross
The field strength is proportional to the line density
The field is tangent to the magnetic field line
The field lines can form open loops

Answer 1

The field lines can form open loops

Question 2

If a moving charged particle enters a region with a magnetic field perpendicular to the direction of motion and begins to follow a curved path, which of the following sets of conditions will result in the largest radius?
Mass m, speed v, charge q, magnetic field B
Mass 2m, speed v, charge q, magnetic field 4B
Mass 2m, speed v, charge 4q, magnetic field B
Mass m, speed 2v, charge 2q, magnetic field 2B

Answer 2

Mass m, speed v, charge q, magnetic field B

Question 3

Which of the three following statements about magnetic fields is false?
Magnetic field lines can never cross one another Magnetic field lines, unlike electric field lines, never end
A charged particle travelling anti-parallel to a magnetic field does not experience a force from that field.
None of the three statements are false
All three statements are false

Answer 3

None of the three statements are false

Question 4

An electron is initially moving in the positive x-direction, when suddenly a uniform magnetic  field is turned on.  The electron is observed to be deflected in the negative y-direction.In which direction is the magnetic  field?
positive x-direction
negative x-direction
positive y-direction
negative y-direction
positive z-direction
negative z-direction

Answer 4

negative z-direction