Final Exam 250106 - Department of Electrical and Computer...

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Unformatted text preview: Department of Electrical and Computer Engineering Module 0404215 Electromagnetic (I) Final Exam 25/01/2006 Time allowed: 2 hour Q1 Complete the following statements: (20 points) 1. Two vectors A and B are said to be equal if they have ……………………………………….. 2. If a sphere of radius 2 cm contains a volume charge density given by 4 cos 2 θ (C/m 3 ), then the total charge contained in the sphere is ……………… 3. The curl of a vector field is a measure of the ………………. of the vector field per unit area Δs , with the orientation of Δs chosen such that the ………………… is ……………………. 4. Stokes’s theorem transforms the ……………………… of the curl of a vector field into a ……………………. of the field over a contour that bounds the surface. 5. If ε is independent of the magnitude of E, then the material is said to be………..because D and E are related……..…...., and if it is independent of the direction of E, the material is said to be............... 6. For a spherical volume of radius a contains a uniform charge density ρ v , the value for D, if R ≥ a, is …………… ∧ ∧ 7. Given That E = (3x 2 + y ) x + x y kV/m, then the work done in moving a -2 μC charge from (0,5,0) to (2,-1,0) by taking the path y = 5-3x is …………………. 8. At the boundary between two different media, the normal component of B is …..... and the tangential components of H are related by ……………..……………………… 9. The inductance of circuit is defined as the ratio of ……… linking the circuit to the ………… 10. Electric and magnetic forces exhibit a number of important differences: 1………………………………….. 2 ……………………………….. Q2 Two extensive homogeneous isotropic dielectrics meet on plane z = 0 . For z ≥ 0 , ε r1 = 4 and ∧ ∧ ∧ for z ≤ 0 , ε r 2 = 3 . A uniform electric field E 1 = 5 x − 2 y + 3 z kV/m exists for z ≥ 0 . Find: (a) E 2 for z ≤ 0 (b) The angles which E 1 and E 2 make with the interface (c) The energy densities in J/m 3 in both dielectrics (d) The energy with a cube of side 2 m centered at (3, 4, -5) (10 points) Q3 A long (practically infinite) straight wire of radius a carries a steady current I that is uniformly distributed over the cross section of the wire. Determine the magnetic filed H at r from the axis of the wire and plot the magnitude of H as a function of r for (a) inside the wire ( r ≤ a ) and (b) outside the wire ( r ≥ a ) (10 points) Q4 Obtain an expression for B at a point on the axis of a very long solenoid with radius a, situated at its end points. Show how does B at the end points compare to B at the midpoint of the solenoid? (6 points) Q5 Two coaxial circular wires of radii a and b (b>a) are separated by distance h (h>>a, b) as shown in the figure. Find the mutual inductance between wires? (4 points) ALL THE BEST DR OMAR AL SARAEREH www.Husni.Net ...
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