Deck 7: Electricity and Magnetism

Question 1

To say that electric charge is conserved means that no case has ever been found where

A)the total charge on an object has changed.
B)the net amount of negative charge on an object is unbalanced by a positive charge on another object.
C)the total amount of charge on an object has increased.
D)net charge has been created or destroyed.
E)none of the above

Answer 1

D

Question 2

A negatively charged rod is brought near a metal can that rests on a wood table. You touch the opposite side of the can momentarily with your finger. The can is then

A)positively charged.
B)negatively charged.
C)uncharged.
D)charged the same as it was.

Answer 2

A

Question 3

Every proton in the universe is surrounded by its own

A)electric field.
B)gravitational field.
C)both A and B
D)none of the above

Answer 3

C

Question 4

A positive ion has more

A)electrons than neutrons.
B)electrons than protons.
C)protons than electrons.
D)protons than neutrons.
E)neutrons than protons.

Question 5

Strip electrons from an atom and the atom becomes a

A)positive ion.
B)negative ion.
C)different element.

Question 6

In an electrically neutral atom the number of protons in the nucleus is equal to the number of

A)electrons that surround the nucleus.
B)neutrons in the nucleus.
C)both A and B
D)neither A nor B

Question 7

A conductor differs from an insulator in that a conductor has

A)more electrons than protons.
B)more protons than electrons.
C)more energy than an insulator.
D)faster moving molecules.
E)none of the above

Question 8

The unit of electric charge, the coulomb, is the charge on

A)one electron.
B)a specific large number of electrons.

Question 9

A balloon will stick to a wooden wall if the balloon is charged

A)negatively.
B)positively.
C)either negatively or positively.
D)neither negatively nor positively.

Question 10

The electrical forces between charges depends on the

A)magnitude of electric charges.
B)separation distance between electric charges.
C)both A and B
D)none of the above

Question 11

The fundamental force underlying all chemical reactions is

A)gravitational.
B)nuclear.
C)centripetal.
D)electrical.
E)none of the above

Question 12

Rub electrons from your hair with a comb and the comb becomes

A)negatively charged.
B)positively charged.

Question 13

When the distance between two charges is halved, the electrical force between the charges

A)quadruples.
B)doubles.
C)halves.
D)is reduced by one-quarter.
E)none of the above

Question 14

An electron and a proton

A)attract each other.
B)repel each other.

Question 15

To say that an object is electrically polarized is to say

A)it is electrically charged.
B)its charges have been rearranged.
C)its internal electric field is zero.
D)it is only partially conducting.
E)it is to some degree magnetic.

Question 16

To say that electric charge is conserved is to say that electric charge

A)may occur in an infinite variety of quantities.
B)is a whole-number multiple of the charge of one electron.
C)will interact with neighboring electric charges.
D)can neither be created nor destroyed.

Question 17

Which force binds atoms together to form molecules?

A)gravitational
B)nuclear
C)electrical
D)centripetal
E)none of the above

Question 18

The electrical force between charges is strongest when the

A)charges are close together.
B)charges are far apart.
C)electric force is constant everywhere.

Question 19

A main difference between gravitational and electric forces is that electrical forces

A)attract.
B)repel or attract.
C)obey the inverse-square law.
D)act over shorter distances.
E)are weaker.

Question 20

A difference between electric forces and gravitational forces is that electrical forces include

A)separation distance.
B)repulsive interactions.
C)the inverse-square law.
D)infinite range.
E)none of the above

Question 21

Two charges separated by 1 m exert a 1-N force on each other. If the magnitude of each charge is doubled, the force on each charge is

A)1 N.
B)2 N.
C)4 N.
D)8 N.
E)none of the above

Question 22

A wire that carries an electric current

A)is electrically charged.
B)may be electrically charged.

Question 23

A proton and an electron are placed in an electric field. Which undergoes the greater acceleration?

A)the electron
B)the proton
C)Both accelerate equally.
D)Neither accelerates.

Question 24

An electroscope is charged positively as shown by foil leaves that stand apart. As a negative charge is brought close to the electroscope, the leaves

A)fall closer together.
B)spread farther apart.
C)do not move.

Question 25

Two charges separated by 1 m exert a 1-N force on each other. If the charges are pulled to a 3-m separation distance, the force on each charge will be

A)0)33 N.
B)0)11 N.
C)0 N.
D)3 N.
E)9 N.

Question 26

Electrons are made to flow in a wire when there is

A)an imbalance of charges in the wire.
B)more potential energy at one end of the wire than the other.
C)a potential difference across its ends.

Question 27

The electrical force on a 2-C charge is 60 N. What is the value of the electric field at the place where the charge is located?

A)20 N/C
B)30 N/C
C)60 N/C
D)120 N/C
E)240 N/C

Question 28

A coulomb of charge that passes through a 6-V battery is given

A)6 joules.
B)6 amperes.
C)6 ohms.
D)6 watts.
E)6 newtons.

Question 29

An electron is pushed into an electric field where it acquires a 1-V electrical potential. If two electrons are pushed the same distance into the same electric field, the electrical potential of the two electrons is

A)0)25 V.
B)0)5 V.
C)1 V.
D)2 V.
E)4 V.

Question 30

If you use 10 J of work to push a coulomb of charge into an electric field, its voltage with respect to its starting position is

A)less than 10 V.
B)10 V.
C)more than 10 V.

Question 31

About how much electrical resistance does the human body have?

A)200,000 ohms
B)300,000 ohms
C)400,000 ohms
D)500,000 ohms

Question 32

Normally a balloon charged to several thousand volts has a relatively small amount of

A)charge.
B)energy.
C)both
D)neither

Question 33

The units used to measure electrical resistance are called

A)volts.
B)AC.
C)ohms.
D)watts.

Question 34

Charge carriers in a metal are electrons rather than protons because electrons are

A)negative.
B)smaller.
C)loosely bound.
D)all of the above
E)none of the above

Question 35

If you use 10 J of work to push a charge into an electric field and then release the charge, as it flies past its starting position, its kinetic energy is

A)less than 10 J.
B)10 J.
C)more than 10 J.

Question 36

A charged balloon neatly illustrates that something can have a great amount of

A)potential energy and a low voltage.
B)voltage and a small potential energy.
C)both voltage and potential energy.
D)none of the above

Question 37

To be safe in the unlikely case of a lightning strike, it is best to be inside a building framed with

A)steel.
B)wood.
C)both the same

Question 38

Two charges separated by one meter exert a 1-N force on each other. If the charges are pushed to 0.25-m separation, the force on each charge will be

A)1 N.
B)2 N.
C)4 N.
D)8 N.
E)16 N.

Question 39

The electric field around an isolated electron has a certain strength 1 cm from the electron. The electric field strength 2 cm from the electron is

A)half as much.
B)the same.
C)twice as much.
D)four times as much.
E)none of the above

Question 40

An ampere is a unit of electrical

A)pressure.
B)current.
C)resistance.
D)all of the above
E)none of the above

Question 41

A woman experiences an electrical shock. The electrons making the shock come from the

A)woman's body.
B)ground.
C)power plant.
D)hair dryer.
E)electric field in the air.

Question 42

When two lamps are connected in parallel to a battery, the electrical resistance that the battery senses is

A)more than the resistance of either lamp.
B)less than the resistance of either lamp.
C)neither A nor B

Question 43

A wire carrying a current is normally charged

A)negatively.
B)positively.
C)not at all.

Question 44

A 10 ohm resistor has 5 A current in it. What is the voltage across the resistor?

A)5 V
B)10 V
C)15 V
D)20 V
E)more than 20 V

Question 45

When a light switch is turned on in a DC circuit, the average speed of electrons in the lamp is

A)the speed of sound waves in metal.
B)the speed of light.
C)1000 cm/s.
D)less than 1 cm/s.
E)dependent on how quickly each electron bumps into the next electron.

Question 46

The current through a 10 ohm resistor connected to a 120-V power supply is

A)1 A.
B)10 A.
C)12 A.
D)120 A.
E)none of the above

Question 47

Alternating current is normally produced by a

A)battery.
B)generator.
C)both A and B
D)neither A nor B

Question 48

Electrons move in an electrical circuit

A)by being bumped by other electrons.
B)by colliding with molecules.
C)by interacting with an established electric field.
D)because the wires are so thin.
E)none of the above

Question 49

When a pair of 1 ohm resistors are connected in series, their combined resistance is

A)1 ohm, and when connected in parallel, 2 ohms.
B)2 ohms, and when in parallel, 1 ohm.
C)1/2 ohm, and when in parallel, 2 ohms.
D)2 ohms, and when in parallel, 1/2 ohm.
E)none of the above

Question 50

When a battery does 24 J of work on 10 C of charge, the voltage it supplies is

A)2)4 V.
B)4)2 V.
C)24 V.
D)240 V.
E)none of the above

Question 51

In an electric circuit, the safety fuse is connected to the circuit in

A)series.
B)parallel.

Question 52

The current in a 100-W bulb connected to a 120-V source is

A)0)5 A.
B)1)2 A.
C)12,000 A.
D)none of the above

Question 53

When two lamps are connected in series to a battery, the electrical resistance that the battery senses is

A)more than the resistance of either lamp.
B)less than the resistance of either lamp.
C)neither A nor B

Question 54

The source of electrons lighting an incandescent AC light bulb is

A)the power company.
B)electrical outlet.
C)atoms in the light bulb filament.
D)the wire leading to the lamp.
E)the source voltage.

Question 55

When a 10-V battery is connected to a resistor, 2 A of current flow in the resistor. What is the resistor's value?

A)2 ohms
B)5 ohms
C)10 ohms
D)20 ohms
E)more than 20 ohms

Question 56

In a common DC circuit, electrons move at the speed of

A)a fraction of a centimeter per second.
B)many centimeters per second.
C)a sound wave.
D)light.
E)none of the above

Question 57

The source of electrons in an ordinary electrical circuit is

A)a dry cell, wet cell, or battery.
B)the back emf of motors.
C)the power station generator.
D)the electrical conductor itself.
E)none of the above

Question 58

The electric power of a lamp that carries 2 A at 120 V is

A)1/6 W.
B)2 W.
C)60 W.
D)20 W.
E)240 W.

Question 59

Which statement is correct?

A)Current flows through a circuit.
B)Voltage flows through a circuit.
C)Resistance is established across a circuit.
D)Current causes voltage.

Question 60

There are electrons in the filament of the AC lamp in your bedroom. When you turn on the lamp and it glows, the glowing comes from

A)different electrons; the ones that flow in the circuit to your lamp.
B)the same electrons.
C)the positive charges that flow in the filament.

Question 61

The number of electrons delivered daily to an average American home by an average power utility in the mid-1980s was

A)zero.
B)110.
C)220.
D)billions of billions.
E)none of the above

Question 62

Magnetic domains normally occur in

A)iron.
B)copper.
C)silver.
D)all of the above
E)none of the above

Question 63

As more lamps are put into a series circuit, the overall current in the power source

A)increases.
B)decreases.
C)stays the same.

Question 64

The source of all magnetism is

A)tiny pieces of iron.
B)tiny domains of aligned atoms.
C)ferromagnetic materials.
D)moving electric charge.
E)none of the above

Question 65

Compared to the resistance of two resistors connected in series, the same two resistors connected in parallel have

A)more resistance.
B)less resistance.
C)the same resistance.

Question 66

An iron rod becomes magnetic when

A)positive ions accumulate at one end and negative ions at the other end.
B)its atoms are aligned having plus charges on one side and negative charges on the other.
C)the net spins of its electrons are in the same direction.
D)its electrons stop moving and point in the same direction.
E)none of the above

Question 67

An iron nail is more strongly attracted to the

A)north pole of a magnet.
B)south pole of a magnet.
C)north or south pole-no difference really.

Question 68

The power dissipated in a 4 ohm resistor carrying 3 A is

A)7 W.
B)18 W.
C)36 W.
D)48 W.
E)not enough information given

Question 69

What is the power rating of a light bulb when 0.8 A flow through it when connected to a 120-V outlet?

A)12 W
B)15 W
C)60 W
D)96 W
E)120 W

Question 70

When we say an appliance "uses up" electricity, we really are saying that

A)current disappears.
B)electric charges are dissipated.
C)the main power supply voltage is lowered.
D)electrons are taken out of the circuit and put somewhere else.
E)electron kinetic energy is changed into heat.

Question 71

Like kinds of magnetic poles repel while unlike kinds of magnetic poles

A)attract.
B)repel also.
C)may attract or repel.

Question 72

The headlights, radio, and defroster fan in an automobile are connected in

A)series.
B)parallel.

Question 73

If you plug an electric toaster rated at 110-V into a 220-V outlet, current in the toaster will be about

A)half what is should be.
B)the same as if it were plugged into 110-V.
C)more than twice what it should be.
D)twice what it should be.

Question 74

Surrounding every moving electron is

A)a magnetic field.
B)an electric field.
C)both A and B
D)none of the above

Question 75

Several paper clips dangle from the north pole of a magnet. The induced pole in the bottom of the lowermost paper clip is a

A)north pole.
B)south pole.
C)north or south pole-no difference really.

Question 76

In the 110-V circuit shown,

A)110 C of charge flow through the lamp every second.
B)110 J of energy are converted to heat and light in the circuit every second.
C)110 J of energy are given to each coulomb of charge making up the current in the circuit.
D)110 J of energy are shared among all the coulombs in the circuit at any instant.
E)none of the above.

Question 77

Magnetic field lines about a current-carrying wire

A)extend radially from the wire.
B)circle the wire in closed loops.
C)both A and B
D)neither A nor B

Question 78

Magnetism is due to the motion of electrons as they

A)move around the nucleus.
B)spin on their axes.
C)both A and B
D)none of the above

Question 79

Moving electric charges will interact with

A)an electric field.
B)a magnetic field.
C)both A and B
D)none of the above

Question 80

As more lamps are put into a parallel circuit, the overall current in the power source

A)increases.
B)decreases.
C)stays the same.