Magnetic Fields unit test
A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.
Choosing an Ampèrian loop
Biot-Savart law
Circular motion in a magnetic field
Ampère's law vs Biot-Savart
Field of a finite wire segment
Field of a long straight wire
Right-hand rules summary
Velocity selector
Force on a current-carrying wire
Field of a toroid
Hall effect
Why magnetic force does no work
Short answer 1. Define or explain: Torque on a current loop
3 ptsShort answer 2. Define or explain: Magnetic dipole
3 ptsShort answer 3. Define or explain: Field at the center of a circular loop
3 ptsShort answer 4. Define or explain: Force between parallel wires
3 ptsFree response
10 ptsA long straight cylindrical conductor of radius R = 2.0 mm carries a steady current I = 5.0 A distributed uniformly over its cross-section.
State Ampère’s law and use it to derive the magnetic field magnitude at a radius r inside the conductor (r < R).
Derive the field for r > R and evaluate the field at r = 1.0 mm, at r = R, and at r = 6.0 mm.
Describe a graph of B versus r from r = 0 to r = 3R.
A second parallel wire 0.10 m away carries 3.0 A in the same direction. Determine the magnitude of the force per unit length between the wires and state whether it is attractive or repulsive.
The straight wire is replaced by a circular loop of radius 0.050 m carrying 5.0 A. Use the Biot–Savart law to determine the field at the center of the loop, and explain why Ampère’s law is not a convenient tool for this geometry.