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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 = 53x 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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 Spring '12
 OmarSarayra
 Electromagnet

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