1. As used in the laws of refraction and reflection, the "normal" direction is:
a) tangent to the interface.
b) along the incident ray.
c) perpendicular to the electric field vector of the ray.
d) perpendicular to the interface.
2. At any point the magnetic field lines are in the direction of:
a) The magnetic force on a moving positive charge.
b) The magnetic force on a moving negative charge.
c) The velocity of a moving negative charge.
d) None of the above.