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Unformatted text preview: 1) Alpha particles (charge = +2e, mass = 6.68 x 10-27 kg) are accelerated in a cyclotron to a final orbit
radius of )
m. The magnetic field in the cyclotron is )
T. The kinetic energy of an alpha particle in
the final orbit is closest to:
A) ) MeV
B) ) MeV
C) ) MeV
D) ) MeV
E) ) MeV
2) If you were to cut a small permanent bar magnet in half,
A) one piece would be a magnetic north pole and the other piece would be a south pole.
B) neither piece would be magnetic.
C) each piece would in itself be a smaller bar magnet with both north and south poles.
D) each piece would contain both north and south poles, but on a given piece the intensity of the north and
south poles would not necessarily be equal.
E) None of these statements is true.
3) Which of the following is an accurate statement?
A) A current carrying loop of wire tends to line up with its plane parallel to an external magnetic field in
which it is positioned
B) A magnetic field line is, by definition, tangent to the direction of the magnetic force on a moving charge
at a given point in space.
C) The magnetic force on a moving charge does not change its energy.
D) The magnetic force on a current carrying wire is greatest when the wire is parallel to the magnetic field.
E) None of these
Answer: C In this figure, a uniform magnetic field of magnitude 0.80 T in the negative z-direction is present in a
region of space. A uniform electric field is also present.
4) In the above figure, an electron, projected with an initial velocity V0 = ) x 104 m/s in the positive xdirection, traverses the region without deflection. The electric field vector, in kV/m, is closest to:
A) - ) j
B) + ) i
C) + ) i
D) + ) j
E) - ) j
Answer: A 5) In the figure above, a wire segment 1.2 m long carries a current I = 3.5 A, and is oriented as shown. A
uniform magnetic field of magnitude 0.50 T is present as shown. Right-handed coordinates are used (as
standard, +z is into the page). The magnetic force on the wire segment, in SI units, is closest to:
A) +1.6 j
B) -1.6 k
C) +1.6 k
D) +1.8 j - 1.6 k
E) -1.8 j + 1.6 k
Figure 27.8 A rigid circular loop has a radius of 0.20 m and is in the x-y plane. A clockwise current I is carried by the
loop, as shown. The magnitude of the magnetic moment of the loop is 0.75 Am2. A uniform external
magnetic field, B = 0.20 T in the positive x-direction, is present.
6) In the above figure, the current in the loop is closest to:
A) 3.0 A
B) 4.5 A
C) 6.0 A
D) 7.5 A
E) 9.0 A
7) In the figure above, the magnitude of the magnetic torque exerted on the loop is closest to:
A) 0.15 N m
B) 0.25 N m
C) 0.35 N m
D) 0.45 N m
E) 0.55 N m
8) A point charge Q moves on the x-axis in the positive direction with a speed of ) m/s. A field point is
on the y-axis at y = + ) mm. The magnetic field produced at the field point, as the charge moves through
the origin, is equal to )
mT pointing in negative z direction. The charge Q is closest to:
A) - ) mC
B) + ) mC
C) - ) mC
D) + ) mC
E) + ) mC Answer: A 9) A circular loop of radius 10 cm and three long straight wires carry currents of I1 = ) A, I2 = ) A, I3
= ) A, and I4 = ) A, respectively, as shown. Each straight wire is 20 cm from the center of the loop. In
Figure 28.1, the y-component of the resultant magnetic field at the center of the loop is closest to:
A) - ) µ T
B) - ) µ T
C) - ) µ T
D) + ) µ T
E) + ) µ T
Answer: A 10) A solenoid shown above, is wound with ) turns on a form 4 cm in diameter and 50 cm long. The
windings carry a current in the sense that is shown. The current produces a magnetic field, of magnitude
) mT, at the center of the solenoid. In Figure 28.7, the current in the solenoid windings is closest to:
A) ) A
B) ) A
C) ) A
D) ) A
E) ) A
Answer: A 11) In the figure above, a wire and a 10 ohm resistor are used to form a circuit in the shape of a square, 20
cm by 20 cm. A uniform but non-steady magnetic field is directed into the plane of the circuit. The
magnitude of the magnetic field is decreased from )
T to )
T in a time interval of ) ms. The
average induced current and its direction through the resistor, in this time interval, are closest to:
A) ) mA, from b to a
B) ) mA, from b to a
C) ) mA, from a to b
D) ) mA, from a to b
E) ) mA, from a to b
Answer: A 12) In the figure above, a coil of wire is placed on the axis of a solenoid carrying a DC current. Which of
the following will NOT result in an EMF being induced in the coil?
A) Rotate the coil about the x-axis.
B) Rotate the coil about the y-axis.
C) Rotate the coil about the z-axis.
D) Move the coil toward point P.
E) Change the current in the solenoid.
Answer: C 13) In the figure above, the inner loop carries a current I that is increasing. The resistor R is in the outer
loop. The induced current through the resistor R is:
B) from a to b C) from b to a
Answer: B 60V )H )Ω
14) An R-L circuit shown above, has a 60 V battery, a ) H inductor, a ) ohm resistor, and a switch S, in
series, as shown. Initially, the switch is open, and there is no magnetic flux in the inductor. At time t = 0 s,
the switch is closed. In Figure 30.1a, when the time t = )
s, the current in the circuit is closest to:
A) ) A
B) ) A
D) ) A
E) ) A
Answer: A A non-planar rigid loop shown above, has two vertical sections, numbered 1 and 3, which are 20 cm long.
It also has two 90 degree arc sections, numbered 2 and 4. The curved sections have a radius of 8 cm, and
the centers are on the z-axis. The loop carries a current of 15 A, as shown. A straight wire lies on the zaxis and carries a current of 25 A, as shown.
15) The force exerted on section 1 due to the 25 A current is closest to:
B) (+2 x 10 -4 N) i
C) (-2 x 10 -4 N) j
D) (-4 x 10 -4 N) i
E) (+4 x 10 -4 N) j
16) In the figure above, the force exerted on section 2 due to the 25 A current is closest to:
B) (+1.2 x 10 -4 N) i
C) (-1.2 x 10 -4 N) j
D) (+1.7 x 10 -5 N) i + (1.7 x 10 -5 N) j
E) (+1.7 x 10 -5 N) i - (1.7 x 10 -5 N) j Answer: A ...
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