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Unformatted text preview: MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Figure 29.1
«n:— 20 cm —:h K K K I
x K x 20 CH1
X X X lﬂﬂ 1) In Fig. 29.1, a wire and a 10—0 resistor are used to form a circuit in the shape of a square, 20 cm by 1) 20 cm. A uniform but nonsteady magnetic field is directed into the plane of the circuit. The
magnitude of the magnetic field is decreased from 1.50 T to 0.50 T in a time interval of 32 ms. The
average induced current and its direction through the resistor, in this time interval, are closest to: A) 130 mA, from b to a B) 75 mA, from b to a C) 130 mA, from a to b D) 190 mA, from a to b E) 75 mA, from a to b Figure 29.5 2
+ 2) In Fig. 29.5, a coil of wire is placed on the axis of a solenoid carrying a DC current. Which of the 2)
following will NOT result in an EMF being induced in the coil?
A) Move the coil toward point P.
B) Rotate the coil about the x—axis.
C) Rotate the coil about the y—axis.
D) Rotate the coil about the z—axis.
E) Change the current in the solenoid. Figure 29.7 3) In Fig. 29.7, a straight wire carries a steady current I. A bar is in contact with a pair of circular rails, 3)
and rotates about the straight wire. The induced current through the resistorR is:
A) zero B) from b to a C) from a to b Figure 29.9 4) In Fig. 29.9, a bar magnet moves away from the solenoid. The induced current through the resist01 4)
A) zero B) from a to b C) from b to a Figure 29.10 T. 5) In Fig. 29.10, a bar is in contact with a pair of parallel rails and is in motion with velocity v. A 5)
uniform magnetic field is present. The induced current through the resistorR is:
A) zero B) from b to a C) from a to b 6) A bar magnet is held vertically with its upper end a little bit below the center of a horizontal metal
ring. The upper end of the magnet is its north pole (see Fig. 29.12). The bar magnet is now dropped.
An observer views the ring from above its center. To this observer, how will the induced current in the ring behave as the magnet falls?
A) The current will ﬂow clockwise and be increasing.
B) The current will ﬂow clockwise and be decreasing. 7) In Fig. 29.20, a bar is in contact with a pair of parallel rails. A steady, uniform, magnetic field B is
present. The bar is in motion with velocity v. The polarity of the induced emf in terminals X and Y
is: C) The current will ﬂow counterclockwise and be decreasing.
D) The current will ﬂow counterclockwise and be increasing. E) The induced current will be zero. A) Y is positive and X is negative
B) X and Y are at the same potential
C) X is positive and Y is negative Figure 29.12 Figure 29.20 6) 7) ...
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- Spring '10
- Magnetic Field, bar magnet