(Multiple choice)

(1)

A conducting loop lies in the plane of this page and carries a clockwise induced current. Which of the following statements could be true? 

(a) A constant magnetic field is directed into the page.  

(b) A constant magnetic field is directed out of the page. 

(c) An increasing magnetic field is directed into the page. 

(d) A decreasing magnetic field is directed into the page. 

(e) A decreasing magnetic field is directed out of the page.

(2)

If the current through an inductor were doubled, the energy stored in the inductor would be 

(a) The same. 

(b) Doubled. 

(c) Quadrupled. 

(d) Halved. 

(e) Quartered.

(3)

Two identical bar magnets are dropped from equal heights. Magnet A is dropped from above bare earth, whereas magnet B is dropped from above a metal plate. Which magnet strikes first? 

(a) Magnet A 

(b) Magnet B 

(c) Both strike at the same time. 

(d) Whichever has the N pole toward the ground. 

(e) Whichever has the S pole toward the ground.

(4) True or false: 

(a) The induced emf in a circuit is proportional to the magnetic flux through the circuit. 

(b) There can be an induced emf at an instant when the flux through the circuit is zero. 

(c) Lenz's law is related to the conservation of energy. 

(d) The inductance of a solenoid is proportional to the rate of change of the current in it. 

(e) The magnetic energy density at some point in space is proportional to the square of the magnetic field at that point.