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177 Cards in this Set

  • Front
  • Back

Suitable units for u0 are

Tesla-meter/ampere

A coulomb is

The amount of charge that flows past a point in one second when the current is 1A

In Ampere's Law,  Bn · dns = µ0i, the integration must be over any

In Ampere's Law, Bn · dns = µ0i, the integration must be over any

Closed path

In Ampere's Law, Bn · dns = µ0i,, the symbol ds is

none of the above

In Ampere's law, Bn · dns = µ0i,the directino of the integration around the path

none of the above

A long straight wire carrying a 3.0 A current enters a room through a window 1.5 m high and1.0 m wide. The path integral Bn · dns around the window frame has the value (in T·m):

3.8x10^-6

Two long straight wires enter a room through a door. One carries a current of 3.0 A into theroom while the other carries a current of 5.0 A out. The magnitude of the path integral Bn ·dnsaround the door frame is:

2.5x10^(-6)T*m

If the magnetic field Bn is uniform over the area bounded by a circle with radius R, the netcurrent through the circle is:

0

The magnetic field at any point is given by Bn = Anr × ˆk, where nr is the position vector of thepoint and A is a constant. The net current through a circle of radius R, in the xy plane andcentered at the origin is given by:

2pi(AR^2)/u0

A hollow cylindrical conductor (inner radius = a, outer radius = b) carries a current i uniformlyspread over its cross section. Which graph below correctly gives B as a function of the distancer from the center of the cylinder?

A long straight cylindrical shell carries current i parallel to its axis and uniformly distributedover its cross section. The magnitude of the magnetic field is greatest:

at the outer surface of the shell

A long straight cylindrical shell has inner radius Ri and outer radius Ro. It carries currenti, uniformly distributed over its cross section. A wire is parallel to the cylinder axis, in thehollow region (rRo). Weconclude that the wire:

is on the cylinder axis and carries current i in the direction opposite to that of the currentin the shell

A long straight cylindrical shell has inner radius Ri and outer radius Ro. It carries a current i,uniformly distributed over its cross section. A wire is parallel to the cylinder axis, in the hollowregion (r

does not carry any current

The magnetic field B inside a long ideal solenoid is independent of:

the cross-sectional area of the solenoid

Two long ideal solenoids (with radii 20 mm and 30 mm, respectively) have the same numberof turns of wire per unit length. The smaller solenoid is mounted inside the larger, along acommon axis. The magnetic field within the inner solenoid is zero. The current in the innersolenoid must be:

the same as the current in the outer solenoid

Magnetic field lines inside the solenoid shown are:

Magnetic field lines inside the solenoid shown are:

toward the top of the page

Solenoid 2 has twice the radius and six times the number of turns per unit length as solenoid1. The ratio of the magnetic field in the interior of 2 to that in the interior of 1 is:

6

A solenoid is 3.0 cm long and has a radius of 0.50 cm. It is wrapped with 500 turns of wirecarrying a current of 2.0 A. The magnetic field at the center of the solenoid is:

4.2x10^(-2)T

A toroid with a square cross section carries current i. The magnetic field has its largestmagnitude:

just inside the toroid at its inner surface

A toroid has a square cross section with the length of an edge equal to the radius of the innersurface. The ratio of the magnitude of the magnetic field at the inner surface to the magnitudeof the field at the outer surface is

2

The normal to a certain 1-m2 area makes an angle of 60◦ with a uniform magnetic field.The magnetic flux through this area is the same as the flux through a second area that isperpendicular to the field if the second area is

0.5m^2

Suppose this page is perpendicular to a uniform magnetic field and the magnetic flux throughit is 5Wb. If the page is turned by 30◦ around an edge the flux through it will be:

4.3Wb

A 2-T uniform magnetic field makes an angle of 30◦ with the z axis. The magnetic flux througha 3-m2 portion of the xy plane is:

5.2Wb

A uniform magnetic field makes an angle of 30◦ with the z axis. If the magnetic flux througha 1-m2 portion of the xy plane is 5Wb then the magnetic flux through a 2-m2 portion of thesame plane is:

10Wb

1 weber is the same as:

1 T · m2

1 weber is the same as:

. 1 V · s

The units of motional emf are:

tesla·meter2/second

Faraday’s law states that an induced emf is proportional to

the rate of change of the magnetic flux

The emf that appears in Faraday’s law is:

around the boundary of the surface used to compute the magnetic flux

If the magnetic flux through a certain region is changing with time:

an emf must exist around the boundary

A square loop of wire lies in the plane of the page. A decreasing magnetic field is directed intothe page. The induced current in the loop is:

clockwise

As an externally generated magnetic field through a certain conducting loop increases in magnitude,the field produced at points inside the loop by the current induced in the loop mustbe:

directed opposite to the applied field

At any instant of time the total magnetic flux through a stationary conducting loop is less inmagnitude than the flux associated with an externally applied field. This might occur because:

the applied field is normal to the loop and increasing in magnitude



 A long straight wire is in the plane of a rectangular conducting loop. The straight wire carries
a constant current i, as shown. While the wire is being moved toward the rectangle the current
in the rectangle is:

A long straight wire is in the plane of a rectangular conducting loop. The straight wire carriesa constant current i, as shown. While the wire is being moved toward the rectangle the currentin the rectangle is:

counterclockwise



A long straight wire is in the plane of a rectangular conducting loop. The straight wire carries
an increasing current in the direction shown. The current in the rectangle is:

A long straight wire is in the plane of a rectangular conducting loop. The straight wire carriesan increasing current in the direction shown. The current in the rectangle is:

counterclockwise



A long straight wire is in the plane of a rectangular conducting loop. The straight wire initially
carries a constant current i in the direction shown. While the current i is being shut off, the
current in the rectangle is:

A long straight wire is in the plane of a rectangular conducting loop. The straight wire initiallycarries a constant current i in the direction shown. While the current i is being shut off, thecurrent in the rectangle is:

clockwise



A rectangular loop of wire is placed midway between two long straight parallel conductors as
shown. The conductors carry currents i1 and i2, as indicated. If i1 is increasing and i2 is
constant, then the induced current in the loop is:

A rectangular loop of wire is placed midway between two long straight parallel conductors asshown. The conductors carry currents i1 and i2, as indicated. If i1 is increasing and i2 isconstant, then the induced current in the loop is:

counterclockwise

You push a permanent magnet with its north pole away from you toward a loop of conductingwire in front of you. Before the north pole enters the loop the current in the loop is:

counterclockwise

A vertical bar magnet is dropped through the center of a horizontal loop of wire, with its northpole leading. At the instant when the midpoint of the magnet is in the plane of the loop, theinduced current at point P, viewed from above, is:

essentially zero

A circular loop of wire rotates about a diameter in a magnetic field that is perpendicular tothe axis of rotation. Looking in the direction of the field at the loop the induced current is:

sometimes clockwise and sometimes counterclockwise



 In the experiment shown

In the experiment shown

there is a current in G just after S is opened or closed

The emf developed in a coil X due to the current in a neighboring coil Y is proportional to the:

rate of change of magnetic field in X

One hundred turns of insulated copper wire are wrapped around an iron core of cross-sectionalarea 0.100 m2. The circuit is completed by connecting the coil to a 10-Ω resistor. As themagnetic field along the coil axis changes from 1.00 T in one direction to 1.00 T in the otherdirection, the total charge that flows through the resistor is:

2C



In the circuit shown, there will be a non-zero reading in galvanometer G:

In the circuit shown, there will be a non-zero reading in galvanometer G:

only just after S is opened or closed

A magnet moves inside a coil. Consider the following factors:


I. strength of the magnet


II. number of turns in the coil


III. speed at which the magnet moves


Which can affect the emf induced in the coil?

I, II, III



The graph shows the magnitude B of a uniform magnetic field that is perpendicular to the
plane of a conducting loop. Rank the five regions indicated on the graph according to the
magnitude of the emf induced in the loop, from least to great...

The graph shows the magnitude B of a uniform magnetic field that is perpendicular to theplane of a conducting loop. Rank the five regions indicated on the graph according to themagnitude of the emf induced in the loop, from least to greatest.

2, 4, 3, 1



The circuit shown is in a uniform magnetic field that is into the page. The current in the circuit
is 0.20 A. At what rate is the magnitude of the magnetic field changing? Is it increasing or
decreasing?:

The circuit shown is in a uniform magnetic field that is into the page. The current in the circuitis 0.20 A. At what rate is the magnitude of the magnetic field changing? Is it increasing ordecreasing?:

140 T/s, decreasing



 A changing magnetic field pierces the interior of a circuit containing three identical resistors.
Two voltmeters are connected to the same points, as shown. V1 reads 1 mV. V2 reads:

A changing magnetic field pierces the interior of a circuit containing three identical resistors.Two voltmeters are connected to the same points, as shown. V1 reads 1 mV. V2 reads:

2 mV



A circular loop of wire is positioned half in and half out of a square region of constant uniform
magnetic field directed into the page, as shown. To induce a clockwise current in this loop:

A circular loop of wire is positioned half in and half out of a square region of constant uniformmagnetic field directed into the page, as shown. To induce a clockwise current in this loop:

move it in +x direction



The four wire loops shown have edge lengths of either L, 2L, or 3L. They will move with the
same speed into a region of uniform magnetic field Bn , directed out of the page. Rank them
according to the maximum magnitude of the induced emf, l...

The four wire loops shown have edge lengths of either L, 2L, or 3L. They will move with thesame speed into a region of uniform magnetic field Bn , directed out of the page. Rank themaccording to the maximum magnitude of the induced emf, least to greatest.

1, then 2 and 3 tie, then 4



A square loop of wire moves with a constant speed v from a field-free region into a region
of constant uniform magnetic field, as shown. Which of the five graphs correctly shows the
induced current i in the loop as a function of time t?

A square loop of wire moves with a constant speed v from a field-free region into a regionof constant uniform magnetic field, as shown. Which of the five graphs correctly shows theinduced current i in the loop as a function of time t?





 The figure shows a bar moving to the right on two conducting rails. To make an induced
current i in the direction indicated, a constant magnetic field in region A should be in what
direction?

The figure shows a bar moving to the right on two conducting rails. To make an inducedcurrent i in the direction indicated, a constant magnetic field in region A should be in whatdirection?

Into the page

A car travels northward at 75 km/h along a straight road in a region where Earth’s magneticfield has a vertical component of 0.50 × 10−4 T. The emf induced between the left and rightside, separated by 1.7 m, i

1.8 mV



Coils P and Q each have a large number of turns of insulated wire. When switch S is closed,
the pointer of galvanometer G is deflected toward the left. With S now closed, to make the
pointer of G deflect toward the right one could:

Coils P and Q each have a large number of turns of insulated wire. When switch S is closed,the pointer of galvanometer G is deflected toward the left. With S now closed, to make thepointer of G deflect toward the right one could:

open S



A rod lies across frictionless rails in a constant uniform magnetic field Bn , as shown. The
rod moves to the right with speed v. In order for the emf around the circuit to be zero, the
magnitude of the magnetic field should:

A rod lies across frictionless rails in a constant uniform magnetic field Bn , as shown. Therod moves to the right with speed v. In order for the emf around the circuit to be zero, themagnitude of the magnetic field should:

decrease linearly with time

A rectangular loop of wire has area A. It is placed perpendicular to a uniform magnetic fieldB and then spun around one of its sides at frequency f. The maximum induced emf is:

2πBAf

A rectangular loop of wire is placed perpendicular to a uniform magnetic field and then spunaround one of its sides at frequency f. The induced emf is a maximum when:

the flux is zero



 The diagram shows a circular loop of wire that rotates at a steady rate about a diameter O
that is perpendicular to a uniform magnetic field. The maximum induced emf occurs when the
point X on the loop passes:

The diagram shows a circular loop of wire that rotates at a steady rate about a diameter Othat is perpendicular to a uniform magnetic field. The maximum induced emf occurs when thepoint X on the loop passes:

c

A copper hoop is held in a vertical east-west plane in a uniform magnetic field whose field linesrun along the north-south direction. The largest induced emf is produced when the hoop is:

rotated about an east-west axis

A 10-turn conducting loop with a radius of 3.0 cm spins at 60 revolutions per second in amagnetic field of 0.50 T. The maximum emf generated is:

5.3V

A single loop of wire with a radius of 7.5 cm rotates about a diameter in a uniform magneticfield of 1.6 T. To produce a maximum emf of 1.0 V, it should rotate at:

35 rad/s

A merry-go-round has an area of 300 m2 and spins at 2 rpm about a vertical axis at a placewhere Earth’s magnetic field is vertical and has a magnitude of 5 × 10−5 T. The emf aroundthe rim is:

0



A copper penny slides on a horizontal frictionless table. There is a square region of constant
uniform magnetic field perpendicular to the table, as shown. Which graph correctly shows the
speed v of the penny as a function of time t?

A copper penny slides on a horizontal frictionless table. There is a square region of constantuniform magnetic field perpendicular to the table, as shown. Which graph correctly shows thespeed v of the penny as a function of time t?





A rod with resistance R lies across frictionless conducting rails in a constant uniform magnetic
field Bn , as shown. Assume the rails have negligible resistance. The magnitude of the force that
must be applied by a person to pull the rod t...

A rod with resistance R lies across frictionless conducting rails in a constant uniform magneticfield Bn , as shown. Assume the rails have negligible resistance. The magnitude of the force thatmust be applied by a person to pull the rod to the right at constant speed v is:

B^2L^2v/R

A rod of length L and electrical resistance R moves through a constant uniform magnetic fieldBn , perpendicular to the rod. The force that must be applied by a person to keep the rodmoving with constant velocity nv is:

0

As a loop of wire with a resistance of 10 Ω moves in a constant non-uniform magnetic field, itloses kinetic energy at a uniform rate of 4.0 mJ/s. The induced current in the loop:

is 20 mA

As a loop of wire with a resistance of 10 Ω moves in a non-uniform magnetic field, it loseskinetic energy at a uniform rate of 5 mJ/s. The induced emf in the loop:

is 0.2 V

An electric field is associated with every:

time-dependent magnetic field

A cylindrical region of radius R = 3.0 cm contains a uniform magnetic field parallel to itsaxis. If the electric field induced at a point R/2 from the cylinder axis is 4.5 × 10−3 V/m themagnitude of the magnetic field must be changing at the rate:

0.60 T/s

A cylindrical region of radius R contains a uniform magnetic field parallel to its axis. The fieldis zero outside the cylinder. If the magnitude of the field is changing at the rate dB/dt, theelectric field induced at a point 2R from the cylinder axis is:

(R/4) dB/dt

A cylindrical region of radius R contains a uniform magnetic field, parallel to its axis, withmagnitude that is changing linearly with time. If r is the radial distance from the cylinderaxis, the magnitude of the induced electric field inside the cylinder is proportional to:

r

A cylindrical region of radius R contains a uniform magnetic field, parallel to its axis, withmagnitude that is changing linearly with time. If r is the radial distance from the cylinderaxis, the magnitude of the induced electric field outside the cylinder is proportional to:

1/r

The unit “henry” is equivalent to:

volt-second/ampere



The diagram shows an inductor that is part of a circuit. The direction of the emf induced in
the inductor is indicated. Which of the following is possible?

The diagram shows an inductor that is part of a circuit. The direction of the emf induced inthe inductor is indicated. Which of the following is possible?

The current is increasing and leftward

A 10-turn ideal solenoid has an inductance of 3.5 mH. When the solenoid carries a current of2.0 A the magnetic flux through each turn is:

7.0 × 10−4 wb

A 10-turn ideal solenoid has an inductance of 4.0 mH. To generate an emf of 2.0 V the currentshould change at a rate of:

500A/s

A long narrow solenoid has length f and a total of N turns, each of which has cross-sectionalarea A. Its inductance is:

µ0N2A/l

A flat coil of wire, having 5 turns, has an inductance L. The inductance of a similar coil having20 turns is:

16L

An inductance L, resistance R, and ideal battery of emf E are wired in series. A switch in thecircuit is closed at time 0, at which time the current is zero. At any later time t the current iis given by:

(E/R)(1 − e^(−Rt/L))

An inductance L, resistance R, and ideal battery of emf E are wired in series. A switch in thecircuit is closed at time 0, at which time the current is zero. At any later time t the emf of theinductor is given by:

Ee^(−Rt/L)

An inductance L, resistance R, and ideal battery of emf E are wired in series. A switch in thecircuit is closed at time 0, at which time the current is zero. At any later time t the potentialdifference across the resistor is given by:

E(1 − e^(−Rt/L))

An 8.0-mH inductor and a 2.0-Ω resistor are wired in series to an ideal battery. A switch inthe circuit is closed at time 0, at which time the current is zero. The current reaches half itsfinal value at time

2.8ms

An 8.0-mH inductor and a 2.0-Ω resistor are wired in series to a 20-V ideal battery. A switch inthe circuit is closed at time 0, at which time the current is zero. After a long time the currentin the resistor and the current in the inductor are:

10 A, 10 A

An 8.0-mH inductor and a 2.0-Ω resistor are wired in series to a 20-V ideal battery. A switch inthe circuit is closed at time 0, at which time the current is zero. Immediately after the switchis thrown the potential differences across the inductor and resistor are:

20 V, 0

An inductor with inductance L resistor with resistance R are wired in series to an ideal batterywith emf E. A switch in the circuit is closed at time 0, at which time the current is zero. Along time after the switch is thrown the potential differences across the inductor and resistor

0, E

If both the resistance and the inductance in an LR series circuit are doubled the new inductivetime constant will be:

unchanged



When the switch S in the circuit shown is closed, the time constant for the growth of current
in R2 is:

When the switch S in the circuit shown is closed, the time constant for the growth of currentin R2 is:

L/R2



The diagrams show three circuits with identical batteries, identical inductors, and identical
resistors. Rank them according to the current through the battery just after the switch is
closed, from least to greatest.

The diagrams show three circuits with identical batteries, identical inductors, and identicalresistors. Rank them according to the current through the battery just after the switch isclosed, from least to greatest.

1,3,2



Immediately after switch S in the circuit shown is closed, the current through the battery is

Immediately after switch S in the circuit shown is closed, the current through the battery is

V0/(R1 + R2)

A 3.5-mH inductor and a 4.5-mH inductor are connected in series. The equivalent inductanceis:

8.0 mH

A 3.5-mH inductor and a 4.5-mH inductor are connected in series and a time varying currentis established in them. When the total emf of the combination is 16 V, the emf of the largerinductor is:

9.0 V

A 3.5-mH inductor and a 4.5-mH inductor are connected in parallel. The equivalent inductanceis:

2.0 mH

A 3.5-mH inductor and a 4.5-mH inductor are connected in parallel. When the total emf ofthe combination is 16 V, the rate of change of the current in the larger inductor is:

3.6 × 10^3 A/s

An inductor with inductance L and an inductor with inductance 2L are connected in parallel.When the rate of change of the current in the larger inductor is 1200 A/s the rate of change ofthe current in the smaller inductor is:

2400 A/s

The stored energy in an inductor:

none of the above

An inductance L and a resistance R are connected in series to an ideal battery. A switch in thecircuit is closed at time 0, at which time the current is zero. The energy stored in the inductoris a maximum:

a long time after the switch is closed

An inductance L and a resistance R are connected in series to an ideal battery. A switch inthe circuit is closed at time 0, at which time the current is zero. The rate of increase of theenergy stored in the inductor is a maximum:

at the time t = (L/R) ln 2 after the switch is closed

In each of the following operations, energy is expended. The LEAST percentage of returnableelectrical energy will be yielded by:

sending current through a resistor

A current of 10 A in a certain inductor results in a stored energy of 40 J. When the current ischanged to 5 A in the opposite direction, the stored energy changes by:

30 J

A 6.0-mH inductor is in a series circuit with a resistor and an ideal battery. At the instant thecurrent in the circuit is 5.0 A the energy stored in the inductor is:

7.5 × 10^(−2) J

A 6.0-mH inductor is in a circuit. At the instant the current is 5.0 A and its rate of change is200 A/s, the rate with which the energy stored in the inductor is increasing is:

6.0W

A 6.0-mH inductor and a 3.0-Ω resistor are wired in series to a 12-V ideal battery. A switch inthe circuit is closed at time 0, at which time the current is zero. 2.0 ms later the energy storedin the inductor is:

1.9 × 10^(−2) J

The quantity B^2/µ0 has units of:

J/m^3

A 0.20-cm radius cylinder, 3.0 cm long, is wrapped with wire to form an inductor. At theinstant the magnetic field in the interior is 5.0 mT the energy stored in the field is about:

3.8 × 10^(−6) J



In the diagram, assume that all the magnetic field lines generated by coil 1 pass through coil
2. Coil 1 has 100 turns and coil 2 has 400 turns. Then:

In the diagram, assume that all the magnetic field lines generated by coil 1 pass through coil2. Coil 1 has 100 turns and coil 2 has 400 turns. Then:

none of the above

A charged capacitor and an inductor are connected in series. At time t = 0 the current is zero,but the capacitor is charged. If T is the period of the resulting oscillations, the next time aftert = 0 that the current is a maximum is:

T /4

A charged capacitor and an inductor are connected in series. At time t = 0 the current is zero,but the capacitor is charged. If T is the period of the resulting oscillations, the next time aftert = 0 that the charge on the capacitor is a maximum is:

T /2

A charged capacitor and an inductor are connected in series. At time t = 0 the current is zero,but the capacitor is charged. If T is the period of the resulting oscillations, the next time aftert = 0 that the voltage across the inductor is a maximum is:

T /2

A charged capacitor and an inductor are connected in series. At time t = 0 the current is zero,but the capacitor is charged. If T is the period of the resulting oscillations, the next time aftert = 0 that the energy stored in the magnetic field of the inductor is a maximum is:

T /4

A charged capacitor and an inductor are connected in series. At time t = 0 the current is zero,but the capacitor is charged. If T is the period of the resulting oscillations, the next time aftert = 0 that the energy stored in the electric field of the capacitor is a maximum is:

T /2

A resistor, an inductor, and a capacitor are connected in parallel to a sinusoidal source of emf.Which of the following is true?

The potential differences across all branches are in phase

The rms value of an ac current is:

that steady current that produces the same rate of heating in a resistor as the actualcurrent

The rms value of a sinusoidal voltage is V0/
√2, where V0 is the amplitude. What is the rms
value of its fully rectified wave? Recall that Vrect(t) = |V (t)|.

The rms value of a sinusoidal voltage is V0/√2, where V0 is the amplitude. What is the rmsvalue of its fully rectified wave? Recall that Vrect(t) = |V (t)|.

. V0/√2

A sinusoidal voltage V (t) has an rms value of 100 V. Its maximum value i

141 V

An ac generator produces 10 V (rms) at 400 rad/s. It is connected to a series RL circuit(R = 17.3 Ω, L = 0.025 H). The rms current is:

0.50 A and lags the emf by 30◦

An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50-Ω resistor,a 400-mH inductor, and a 200-µF capacitor. The rms current in amperes is:

0.135

An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50-Ω resistor,a 400-mH inductor, and a 200-µF capacitor. The rms voltage (in volts) across the resistor is:

6.7

An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50-Ω resistor,a 400-mH inductor, and a 200-µF capacitor. The rms voltage (in volts) across the capacitor is:

3.4

An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50-Ω resistor,a 400-mH inductor, and a 200-µF capacitor. The rms voltage (in volts) across the inductor is:

10.8



The ideal meters shown read rms current and voltage. The average power delivered to the load
is:

The ideal meters shown read rms current and voltage. The average power delivered to the loadis:

possibly equal to V I even if the load contains an inductor and a capacitor



 The average power supplied to the circuit shown passes through a maximum when which one
of the following is increased continuously from a very low to a very high value? 

The average power supplied to the circuit shown passes through a maximum when which oneof the following is increased continuously from a very low to a very high value?

R

In a series RLC circuit the rms value of the generator emf is E and the rms value of the currentis i. The current lags the emf by φ. The average power supplied by the generator is given by:

i^2R

The units of the power factor are:

none of these

A series circuit consists of a 15-Ω resistor, a 25-mH inductor, and a 35-µF capacitor. If thefrequency is 100 Hz the power factor is:

0.45

The main reason that alternating current replaced direct current for general use is

ac voltages may be conveniently transformed

A step-down transformer is used to:

decrease the voltage

Iron, rather than copper, is used in the core of transformers because iron:

. has a very high permeability

The core of a transformer is made in a laminated form to:

prevent eddy currents

A generator supplies 100 V to the primary coil of a transformer. The primary has 50 turns andthe secondary has 500 turns. The secondary voltage is:

1000 V

The resistance of the primary coil of a well-designed, 1 : 10 step-down transformer is 1 Ω. Withthe secondary circuit open, the primary is connected to a 12 V ac generator. The primarycurrent is:

essentially zero

The primary of an ideal transformer has 100 turns and the secondary has 600 turns. Then:

the primary current is six times the secondary current

The primary of a 3 : 1 step-up transformer is connected to a source and the secondary isconnected to a resistor R. The power dissipated by R in this situation is P. If R is connecteddirectly to the source it will dissipate a power of:

P/9

In an ideal 1 : 8 step-down transformer, the primary power is 10 kW and the secondary currentis 25 A. The primary voltage is:

3200 V

A source with an impedance of 100 Ω is connected to the primary coil of a transformer and aresistance R is connected to the secondary coil. If the transformer has 500 turns in its primarycoil and 100 turns in its secondary coil the greatest power will be dissipated in the resistor ifR =:

4.0 Ω

Gauss’ law for magnetism:

none of the above

Gauss’ law for magnetism tells us:

that magnetic monopoles do not exist

The statement that magnetic field lines form closed loops is a direct consequence of

Gauss’ law for magnetism

A magnetic field parallel to the x axis with a magnitude that decreases with increasing x butdoes not change with y and z is impossible according to:

Gauss’ law for magnetism

According to Gauss’ law for magnetism, magnetic field lines:

form closed loops

The magnetic field lines due to an ordinary bar magnet:

form closed curves



Four closed surfaces are shown. The areas Atop and Abot of the top and bottom faces and the
magnitudes Btop and Bbot of the uniform magnetic fields through the top and bottom faces
are given. The fields are perpendicular to the faces and ar...

Four closed surfaces are shown. The areas Atop and Abot of the top and bottom faces and themagnitudes Btop and Bbot of the uniform magnetic fields through the top and bottom facesare given. The fields are perpendicular to the faces and are either inward or outward. Rankthe surfaces according to the magnitude of the magnetic flux through the curved sides, leastto greatest.

3, 4, 1, 2

Consider the four Maxwell equations:


1. En ·−→d An = q/60


2. Bn · dAn = 0


3. En · dns = −dΦB/dt


4. Bn · dns = µ0i + µ060 dΦE/dt




Which of these must be modified if magnetic poles are discovered?

Only 2 and 3

One of the Maxwell equations begins with Bn · dns = .... The symbol “dns” means:

none of the above

One of the Maxwell equations begins with En · dns = .... The “◦” symbol in the integral signmeans:

integrate around a closed path

One of the Maxwell equations begins with Bn · dAn = .... The “◦” symbol in the integral signmeans:

integrate over a closed surface

One of the crucial facts upon which the Maxwell equations are based is:

none of the above

Two of Maxwell’s equations contain a path integral on the left side and an area integral on theright. For them:

the path must be the boundary of the area

Two of Maxwell’s equations contain an integral over a closed surface. For them the infinitesimalvector area dAn is always:

perpendicular to the surface and pointing outward

Two of Maxwell’s equations contain a path integral on the left side and an area integral on theright. The directions of the infinitesimal path element dns and infinitesimal area element dAnare:

none of the above

Two of Maxwell’s equations contain a path integral on the left side and an area integral on theright. Suppose the area is the surface of a piece of paper at which you are looking and dAn ischosen to point toward you. Then, the path integral is

counterclockwise around the circumference of the paper

Which of the following equations can be used, along with a symmetry argument, to calculatethe electric field of a point charge?

En · dAn = q/60

Which of the following equations can be used, along with a symmetry argument, to calculatethe magnetic field of a long straight wire carrying current?

Bn · dns = µ0i + µ060dΦE/dt

Which of the following equations can be used to show that magnetic field lines form closedloops?

Bn · dAn = 0

Which of the following equations, along with a symmetry argument, can be used to calculatethe magnetic field produced by a uniform time-varying electric field?

Bn · dns = µ0i + µ060dΦE/dt

Which of the following equations, along with a symmetry argument, can be used to calculatethe electric field produced by a uniform time-varying magnetic field?

En · dns = −dΦB/dt

Which of the following equations, along with a symmetry argument, can be used to calculatethe magnetic field between the plates of a charging parallel plate capacitor with circular plates?

Bn · dns = µ0i + µ060dΦE/dt

Maxwell’s equations, along with an appropriate symmetry argument, can be used to calculate:

none of these

The polarity of an unmarked magnet can be determined using:

a compass

Select the correct statement

gamma rays have higher frequency than infrared waves

Consider: radio waves (r), visible light (v), infrared light (i), x-rays (x), and ultraviolet light(u). In order of increasing frequency, they are

r, i, v, u, x

The order of increasing wavelength for blue (b), green (g), red (r), and yellow (y) light is:

b, g, y, r

Of the following human eyes are most sensitive to:

green light

Which of the following is NOT true for electromagnetic waves?

they travel at different speeds in vacuum, depending on their frequency

The product µ060 has the same units as:

1/velocity2

Maxwell’s equations predict that the speed of electromagnetic waves in free space is given by:

1/(µ060)^(1/2)

Maxwell’s equations predict that the speed of light in free space is

independent of frequency

The speed of light in vacuum is about

3 × 10^10 cm/s

The Sun is about 1.5 × 1011 m away. The time for light to travel this distance is about:

8min

The time for a radar signal to travel to the Moon and back, a one-way distance of about3.8 × 108 m, is:

2.5s

Which of the following types of electromagnetic radiation travels at the greatest speed invacuum?

All of these travel at the same speed

Radio waves differ from visible light waves in that radio waves:

have a lower frequency

Visible light has a frequency of about:

5 × 10^14 Hz

The theoretical upper limit for the frequency of electromagnetic waves is

none of the above (there is no upper limit)

Radio waves of wavelength 3 cm have a frequency of:

10, 000 MHz

Radio waves of wavelength 300 m have a frequency of

1 MHz

If the electric field in a plane electromagnetic wave is given by Em sin[(3×106 m−1)x−ωt], thevalue of ω is:

9 × 10^14 rad/s

An electromagnetic wave is generated by:

any accelerating charge