- A proton is accelerated through a potential difference of 10 kV
and enters a uniform magnetic field at right angles. Calculate the
value of the magnetic flux density necessary to move the proton in
a circular path of radius 10 mm. 
- A piece of wire of cross-sectional area A and resistivity ρ is
bent into a circular loop of radius r and placed in a magnetic
field with its plane at right angles to the field. Determine the
magnitude of the current in the loop if the field is reduced to
zero in time t. 
- A 40 μF capacitor is charged to a voltage of 120 V. How much
work must be done to transfer 60 μC from the negative plate to the
- A point charge of magnitude +q and speed v is located at a
distance d from a long straight wire carrying a current I.
(a) Determine the magnitude of the
force on the charge if it is moving directly towards the wire.
(b) Is the direction of the force
parallel or anti-parallel to the wire? Use a fully labeled sketch
to motivate your answer.