Electrodynamics.
consider a particle of charge q and mass m that travels with velocity u(vector) =vu(unit vector) in the field of an electromagnetic wave in free space. wave propagates in z-direction.
a) what is the force on the particle?
b) in what does this convert to in the special case where the particle moves in the same direction as the wave?
c) under which conditions (if there exist) will this force be eliminated for the previous case?

The dipole moment of the water molecule (h2o) is 6.17x10^-30 c.m. consider a water molecule located at the origin whose dipole moment p points in the +x-direction. a chlorine ion ( of charge-1.60x10^-19c , is located at x=3.00x10^-9m . assume that is much larger than the separation d between the charges in the dipole, so that the approximate expression for the electric field along the dipole axis can be used. a) find the magnitude of the electric force that the water molecule exerts on the chlorine ion. b) what is the direction of the electric force. -x-direction or +x-direction c) is this force attractive or repulsive?