1.

In the figure, the current element idl, the point P, and the three vectors (1, 2, 3) are all in the plane of the page. The direction of dB, due to this current element, at the point P is: A. in the direction marked "1"
 B. in the direction marked "2"
 C. in the direction marked "3"
 D. out of the page
 E. into the page

2.

The magnitude of the magnetic field at point P, at the center of the semicircle shown, is given by: A. m0/R2
 B. m0/2pR
 C. m0i/4pR
 D. m0i/2R
 E. m0i/4R

3. The magnetic field outside a long straight current-carrying wire depends on the distance R from the wire axis according to:
 A. R
 B. 1/R
 C. 1/R2
 D. 1/R3
 E. 1/R3/2

4. The magnetic field (in T) a distance 2 cm from a long straight wire carrying a current of 2 A is about:
 A. 2 × 10–7
 B. 1 × 10–5
 C. 2 × 10–5
 D. 1 × 10–3
 E. 10

5. Two long parallel straight wires carry equal currents in opposite directions. At a point midway between the wires, the magnetic field they produce is:
 A. zero
 B. non-zero and along a line connecting the wires
 C. non-zero and parallel to the wires
 D. non-zero and perpendicular to the plane of the two wires
 E. none of the above

6. Two parallel long wires carry the same current and repel each other with a force F per unit length. If both these currents are doubled and the wire separation tripled, the force per unit length becomes:
 A. 2F/9
 B. 4F/9
 C. 2F/3
 D. 4F/3
 E. 6F

7. A long straight wire carrying a 3.0 A current enters a room through a window 1.5 m high and 1.0 m wide. The path integral around the window frame has the value
(in T×m):
 A. 0.2
 B. 2.5 × 10–7
 C. 3.0 × 10–7
 D. 3.8 × 10–6
 E. none of these

8. Two long straight wires enter a room through a window. One carries a current of 3.0 A into the room while the other carries a current of 5.0 A out. The magnitude in T×m of the path integral around the window frame is:
 A. 2.5 × 10–6
 B. 3.8 × 10–6
 C. 6.3 × 10–6
 D. 1.0 × 10–5
 E. none of these

9. The magnetic field B inside a long ideal solenoid is independent of:
 A. the current
 B. the core material
 C. the spacing of the windings
 D. the cross-sectional area
 E. the direction of the current

10. A toroid has a square cross section with the length of an edge equal to the radius of the inner surface. The ratio of the magnitude of the magnetic field at the inner surface to the magnitude of the field at the outer surface is:
 A. 1/4
 B. 1/2
 C. 1
 D. 2
 E. 4 This is the end of the test. When you have completed all the questions and reviewed your answers, press the button below to grade the test.