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:
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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
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