PHYSICS
Practice Exam 3_A

# Practice Exam 3_A - 1 In the figure the current element idl...

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1. In the figure, the current element i dl, the point P, and the three vectors (1, 2, 3) are all in the plane of the page. At point P the direction of the vector dB, due to this current element, is: A) in the direction marked "3" B) in the direction marked "1" C) out of the page D) into the page E) in the direction marked "2" 2. A 45-mH inductor is connected to an ac source of emf with a frequency of 400 Hz and a rms voltage of 20 V. The RMS current is: 3. In an ideal 1:8 step- down transformer, the primary power is 10 kW and the secondary current is 25 A. The primary voltage is therefore: Page 1

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4. Four long straight wires carry equal currents into the page as shown. The direction of the magnetic FORCE exerted on wire F is: A) east B) west C) north D) zero E) south 5. A hollow cylindrical conductor (inner radius = a , outer radius = b ) carries a current i uniformly spread over its cross-section (shaded). Which graph below correctly gives the magnitude of B as a function of the distance r from the center of the cylinder? b a Page 2