Maxwell guessed that visible light was an electromagnetic wave because of its:
a.frequency.
b.wavelength.
c.speed.
d.energy.
e.polarization.
Ans c
The force on a charged particle created by its motion in a magnetic field is maximum at what angle between the particle velocity and field?
a.zero
b.180
c.90
d.45
e.135
Ans c
If a proton is released at the equator and falls toward the Earth under the influence of gravity, the magnetic force on the proton will be toward the:
a.north.
b.south.
c.east.
d.west.
Ans. C
There is a magnetic force on a particle. It is possible that the particle is:
a.uncharged.
b.stationary.
c.moving in the direction of the magnetic field.
d.not part of a wire.
e.moving opposite the direction of the magnetic field.
Ans. D
There is a current I flowing in a clockwise direction in a square loop of wire that is in the plane of the paper. If the magnetic field B is toward the right, and if each side of the loop has length L, then the net magnetic force acting on the loop is:
a.2ILB.
b.ILB.
c.IBL2.
d.I2BL.
e.zero.
Ans. E
There is a current I flowing in a clockwise direction in a square loop of wire that is in the plane of the paper. If the magnetic field B is toward the right, and if each side of the loop has length L, then the net magnetic torque acting on the loop is:
a.2ILB.
b.ILB.
c.IBL2.
d.I2BL.
e.zero.
Ans. C
A current in a long, straight wire produces a magnetic field. The magnetic field lines:
a.go out from the wire to infinity.
b.come in from infinity to the wire.
c.form circles that pass through the wire.
d.form circles that go around the wire.
e.are parallel to the wire.
Ans d
Two long parallel wires 40 cm apart are carrying currents of 10 A and 20 A in the same direction. What is the magnitude of the magnetic field halfway between the wires?
a.1.0 10-5 T
b.2.0 10-5 T
c.3.0 10-5 T
d.4.0 10-5 T
e.5.0 10-5 T
Ans. A
Two parallel conductors are carrying currents in the same direction. The currents are non-zero and not necessarily equal. The magnitude of the magnetic field midway between them is 40 T. If one of the currents then has its direction reversed, what is the resulting magnitude of the magnetic field midway between them?
a.a value greater than 40 T
b.40 T
c.a value less than 40 T
d.0 T
e.It could be any value.
Ans. A
Two parallel wires are separated by 0.25 m. Wire A carries 5.0 A and Wire B carries 10 A, both currents in the same direction. The force on 0.80 m of Wire A is:
a.half that on 0.80 m of wire B.
b.one-fourth that on 0.80 m of wire B.
c.toward Wire B.
d.away from Wire B.
e.one-eighth that on 0.80 m of wire B.
f. two of the above are correct
Ans. C
A current in a solenoid coil creates a magnetic field inside that coil. The field strength is directly proportional to:
a.the coil area.
b.the current.
c.the coil diameter.
d.Both A and B are valid choices.
e.None of the above choices are valid.
Ans. B
A current in a solenoid with N turns creates a magnetic field at the center of that loop. The field strength is directly proportional to:
a.number of turns in the loop.
b.current strength.
c.length of the solenoid coil.
d.Both choices A and B are valid.
e.None of the above are valid.
Ans. D
A uniform 4.5-T magnetic field passes through the plane of a wire loop 0.10 m2 in area. What flux passes through the loop when the direction of the 4.5-T field is at a 30 angle to the normal of the loop plane?
a.5.0 Tm2
b.0.52 Tm2
c.0.39 Tm2
d.0.225 Tm2
e.0.125 Tm2
Ans. C
According to Lenz's law the direction of an induced current in a conductor will be that which tends to produce which of the following effects?
a.enhance the effect which produces it
b.produce a greater heating effect
c.produce the greatest voltage
d.oppose the effect which produces it
e.produce the greatest magnetic field
Ans. D
A bar magnet is falling through a loop of wire with constant velocity. The south pole enters first. As the magnet leaves the wire, the induced current (as viewed from above):
a.is clockwise.
b.is counterclockwise.
c.is zero.
d.is along the length of the magnet.
e.More information is needed.
Ans. B
A metal rod is falling toward the surface of the Earth near the equator. As it falls, one end of the rod becomes positively charged due to the motional emf of the rod through the Earth's magnetic field. The rod is oriented so that:
a.the rod is vertical with the positive end higher.
b.the rod is horizontal with the positive end toward the north.
c.the rod is horizontal with the positive end toward the east.
d.the rod is horizontal with the positive end toward the west.
e.the rod is horizontal with the positive end toward the south.
Ans. C
A bar magnet is falling through a loop of wire with constant velocity. The north pole enters first. As the south pole leaves the loop of wire, the induced current (as viewed from above) will be:
a.clockwise.
b.counterclockwise.
c.zero.
d.along the length of the magnet.
e.More information is needed.
Ans. A
An inductor, battery, resistance, and ammeter and switch are connected in series. If the switch, initially open, is now closed, what is the current's final value?
a.zero
b.battery voltage divided by inductance
c.battery voltage times inductance
d.battery voltage divided by resistance
e.resistance times inductance
Ans. D
What is the effective (rms) current value for an AC current with an amplitude of 10 A?
a.28 A
b.3.1 A
c.7.1 A
d.14 A
e.20 A
Ans. C
A radar pulse returns 3.0 104 seconds after it is sent out, having been reflected by an object. What is the distance between the radar antenna and the object? (c = 3.00 108 m/s)
a.9.0 104 m
b.4.5 104 m
c.6.0 104 m
d.1.0 104 m
e.2.0 104 m
Ans. B
Find the frequency of x-rays of wavelength 1010 m. (c = 3 108 m/s)
a.3 1018 Hz
b.3 1016 Hz
c.6 109 Hz
d.3 108 Hz
e.6 107 Hz
Ans. A
Two long parallel wires 40 cm apart are carrying currents of 10 A and 20 A in the opposite direction. What is the magnitude of the magnetic field halfway between the wires?
a.1.0 10-5 T
b.2.0 10-5 T
c.3.0 10-5 T
d.4.0 10-5 T
e.5.0 10-5 T
Ans C