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Unformatted text preview: ET331 –Tutorial 10 – Solution, 2005 1 The University of Western Australia School of Electrical, Electronic and Computer Engineering Tutorial Sheet 10 - Solution, 2005 Electromagnetic Theory 331 Question 1 (SADIKU 2 nd edition, problem 9.5, p. 440, 3 rd edition, problem 9.6, p 405) A conducting rod moves with a constant velocity of 3 a z ms-1 parallel to a long straight wire carrying a current of 15 A as shown below. Calculate the emf induced in the rod and state which end is at a higher potential. v 20 cm 40 cm A B 15 A Question 2 The diagram shows in cross section a 20 turn plain square coil of side 0.5 m being used to detect a buried conductor carrying 25 amps at 50 Hz. S 0.5 m 1.0 m ⊗ coil moves over surface Find the mutual inductance between the conductor and the coil in terms of S, the distance of the midpoint of the coil to the point vertically above the conductor. Evaluate the voltage induced in the coil for S = 1.0 m and for S = 0. Where will the voltage be greatest? What is the inductance between the coil and the conductor? (Hint: no additional calculation required!) Question 3 The diagram below shows in cross section a rectangular coil, which rotates at a constant angular velocity of ω radians per second about an axis bisecting the short sides of the coil. A steady magnetic field exists in the neighborhood of the coil due ET331 –Tutorial 10 – Solution, 2005 2 to the presence of a long straight conductor at a distance s from the coil axis, and parallel to it. The coil dimensions are: L × 2 a . ⊗ ⊗ . ω t a a s Find an expression for the voltage developed around the coil (of N turns), in terms of the rotation velocity and time. Express this relation in terms of the product of two factors, the first factor representing the approximate value of voltage assuming a uniform magnetic field, s I B π µ 2 = across the coil, and the second factor representing a “distortion” term, resulting in a non-sinusoidal waveform. Evaluate the voltage for about 6 values in a half cycle, and plot, given the following: ω = 40 π rad/s S = 0.075 m a = 0.05 m L = 1.0 m N = 795 turns I = 50 A Question 4 The diagram shows a cross-sectional view of two telephone circuits which run parallel to each other for a distance of 1.0 km. The diameter of each wire is 1.0 mm. 500mm 500mm 500mm Circuit 1 Circuit 2 • + • + (i) Find the self-inductance of each circuit. (ii) Find the mutual inductance between circuit 1 and circuit 2....
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- Spring '07
- Electromagnet, Magnetic Field, Ampere