#mse45 lm

[neonberk]

mse 45 hw10

Q7. (12 pts.) A coil of wire 0.5 m long and having 20 turns carries a current of 1.0 A. Answer the following: (4 pts.) Compute the flux density if the coil is within a vacuum. (4 pts.) A bar of an iron–silicon alloy, the B-H behavior for which is shown in Figure 20.29, is positioned within the coil. What is the flux density within this bar? (4 pts.) Suppose that a bar of molybdenum is now situated within the coil. What current must be used to produce the same B field in the Mo as was produced in the iron–silicon alloy (part b) using 1.0 A?

Figure 20.29

Table 20.2

12/12

i have no idea how the units work but it does work soo

[neonberk]

mse 45 hw10

Q6. (14 pts.) Assume there exists some hypothetical metal that exhibits ferromagnetic behavior and that has (1) a simple cubic crystal structure, (2) an atomic radius of 0.125 nm, and (3) a saturation flux density of 0.85 T. Determine the number of Bohr magnetons per atom for this material.

14/14

always, make sure your units cancel out nicely ! also we weren't taught this in lecture so,,, thank u google (and hence that complain at the top of my hw)

[neonberk]

mse 45 hw10

Q5. (12 pts) The magnetic flux density within a bar of some material is 0.630 T at an H field of 5 × 10^5 A/m. Compute the following for this material: (4 pts.) The magnetic permeability. (4 pts.) The magnetic susceptibility. (4 pts.) What type(s) of magnetism would you suggest is (are) being displayed by this material? Why?

12/12

*for (c), its better to say paramagnetic since Xm is small and positive

the units for magnetism are confusing as heck

[neonberk]

mse 45 hw10

Q4. (20 pts.) A charge of 2.0 × 10-10 C is to be stored on each plate of a parallel-plate capacitor having an area of 650 mm2 (1.0 in2) and a plate separation of 4.0 mm (0.16 in). Answer the following: (4 pts.) What voltage is required if a material having a dielectric constant of 3.5 is positionedwithin the plates? (4 pts.) What voltage would be required if a vacuum were used? (4 pts.) What are the capacitances for parts (a) and (b)? (4 pts.) Compute the dielectric displacement for part (a). (4 pts.) Compute the polarization for part (a).

20/20

[neonberk]

mse 45 hw10

Q3. (12 pts.) For CaO, the ionic radii for Ca2+ and O2- ions are 0.100 and 0.140 nm, respectively. If an externally applied electric field produces a 5% expansion of the lattice, compute the dipole moment for each Ca2+-O2- pair. Assume that this material is completely unpolarized in the absence of an electric field.

10/12 *charge is ±2 so Q should be 2*e

[neonberk]

mse 45 hw10

Q2. (14 pts.) a. (6 pts.) A parallel-plate capacitor using a dielectric material having an εr of 2.2 has a plate spacing of 2 mm (0.08 in.). If another material having a dielectric constant of 3.7 is used and the capacitance is to be unchanged, what must be the new spacing between the plates? b. (8 pts.) A parallel-plate capacitor with dimensions of 38 mm by 65 mm and a plate separation of 1.3 mm must have a minimum capacitance of 70 pF (7 × 10-11 F) when an ac potential of 1000 V is applied at a frequency of 1 MHz. Which of the materials listed in Table 18.5 are possible candidates? Why?

Table 18.5

14/14

[neonberk]

mse 45 hw10

Q1. (16 pts.) For intrinsic semiconductors, the intrinsic carrier concentration ni depends on the temperature as 𝑛𝑖 ∝ 𝑒𝑥𝑝 (− 𝐸𝑔/2𝑘𝑇). Using this fact and the data in Figure 18.16 for silicon and germanium, determine the band gap energies of these materials.

Figure 18.16

16/16

[neonberk]

mse 45 hw9

Q8. (12 pts.) The following electrical characteristics have been determined for both intrinsic and p-type extrinsic gallium antimonide (GaSb) at room temperature:

Calculate electron and hole mobilities.

10/12 *minor mistakes/math error