a. A positive charge is dropped downward into a uniform magnetic field directed into the page. What direction is the force exerted on the charge as it first enters the magnetic field?
b. A positive charge initially moving to the right enters a region containing a uniform magnetic field. The charge is initially deflected upward as it enters the magnetic field. What must be the direction of the magnetic field?
c. A long, straight wire carries a current. There is a uniform magnetic field directed to the left (not due to the wire) and the force exerted on the wire is directed downward. In what direction is the current?
d. A long, straight wire carries current directed out of the page. What is the directing of the magnetic field that the current generates at a location directly above the wire?
e. A wire loop exists in the plane of the page. An increasing magnetic field directed out of the page penetrates through the loop. What is the direction of the induced current?