A stiff straight copper wire XY is held fixed in a uniform magnetic field of flux density 
, as shown in the figure below.
The wire XY has length 
and makes an angle of 
with the magnetic field.
Calculate the force on the wire due to a constant current of 
in the wire.
The current in the wire is now changed to an alternating current of r.m.s. value 
. Determine the total variation in the force on the wire due to the alternating current.
.
.
