Sample Exam II

1. A 50-cm long rod is moving at a constant speed of 100 cm/s perpendicular to a 0.15T magnetic field. The rod is connected to 10.0 Ohms external resistor. How much force is required to keep the rod moving at constant speed?

(a) 0.27 N  (b) 0.90 N  (c) 6.4 N  (d) 10.0 N 

  2. A 1.0 m long solenoid carries a current of 1000A. If the magnetic field at the center of the solenoid is 8p T, how many turns are in the solenoid?

  (a) 1000 (b)  20000   (c)  30000   (d) 2000

  3. An electron moving with velocity v to the right enters a region of uniform magnetic field that points out of the paper.  After the electron enters this region, it will be

  (a) deflected out of the paper  (b) deflected upward

(c) deflected into the plane of the paper  (d) deflected downward

  4.  Two long parallel wires are placed side-by-side on a horizontal, frictionless table. If the wires carry currents in the opposite directions

(a) wires would move toward one another

(b) wires would move away from one another

(c) wires would be lifted off the table

(d) nothing at all would happen

  5. A/an_______must be inserted INTO the circuit while a/an______ can be attached to the circuit.

  (a) ammeter, voltmeter (b) voltmeter, galvanometer

(c) voltmeter,ammeter  (d) voltmeter, ohmmeter 

  6. A resistance irreversibly converts electrical energy into

  a. mechanical work. b. potential energy. c. chemical energy. d. heat energy

  7. A 1000-turn circular loop coil 30 cm in diameter is initially aligned so that its axis is parallel to the Earth's
magnetic field. In 3 ms the coil is flipped so that its axis is perpendicular to the Earth's magnetic field. If a voltage of
0.166 V is thereby, induced in the coil, what is the value of the Earth's magnetic field?

  8. If the current through the 12 Ohms resistor is 12 A, how much power is dissipated in the resistor?

  9.  A single 10 cm x 10 cm rectangular loop carrying a current of 2 A, is in a magnetic field of 0.4 T.
Find the maximum torque that acts on this loop.

  10. An electric power line carries a current of 1400 A in a location where the earth's magnetic field is 0.50x10^-4 T.
The line makes an angle of 60 degrees with respect to the field. Determine the magnitude of the magnetic force on
a 120-m length of line.

  11. When an external resistor of resistance R1 = 16 Ohms is connected to the terminals of a battery, a current
of 6 A flows through the resistor. When an external resistor of resistance R2 62.4 Ohms is connected instead,
the current is 2 A.

  a. Calculate the emf of the battery.     b. Calculate the internal resistance of the battery.