Unformatted text preview: Department of Electrical and Computer Engineering
Module 0404215 Electromagnetic (I)
Final Exam 10/08/2006
Time allowed: 2 hour
Q1) A coaxial capacitor consists of two concentric, conducting,cylindrical surfaces, one of radius a
and another of radius b, as shown in figure 1. The insulating layer separating the two
conducting surfaces is divided equally into two cylindrical sections, one filled with dielectric ε1
and the other filled with dielectric ε2.
(a) Develop an expression for C in terms of the length l and the given
quantities.
(b) Evaluate the value of C for a = 2mm, b = 4mm, ε1= 2, ε2 = 4 and l = 4cm? (15 points) Q2) (a) Find an expression for the magnetic flux density of a solenoid of
length l and radius a (with l >> a) at a point P on the solenoid axis?
(b) Show how is the inductance of the solenoid related to its number of
turns N and its cross sectional area S?
(15 points) Figure 1
→ ∧ ∧ Q3) In a given region of space the vector magnetic potential is given by A = x 5 cos πy + z (2 + sin πx)
(Wb/m).
(i) Determine the magnetic flux density?
(ii) Calculate the magnetic flux, using two different methods, spassing through a square loop
with 0.25mlong edges if the loop is in the x–y plane, its center is at the origin,
and its edges are parallel to the x and yaxes.
(15 points)
Q4) Three point charges, each with q = 3 nC, are located at the corners of a triangle in the x–y plane,
with one corner at the origin, another at (2 cm,0,0), and the third at (0,2 cm,0). Find the force
acting on the charge located at the origin ?
(5 points) ALL THE BEST
DR OMAR ALSARAEREH www.Husni.Net ...
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 Spring '12
 OmarSarayra
 Electromagnet, Magnetic Field, Department of Electrical and Computer Engineering, 2 cm, magnetic ﬂux density, 0.25M, 0,2 cm

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