Deck 23: Electric Current

Question 1

The unit of electrical resistance is the

A)volt.
B)ampere.
C)ohm.
D)none of the above

Answer 1

ohm.

Question 2

Ohm's law tells us that the amount of current produced in a circuit is

A)directly proportional to voltage.
B)inversely proportional to resistance.
C)both of these
D)neither of these

Answer 2

both of these

Question 3

When you turn on a lamp, the initial current in its filament is greater at first, rather than a moment later, which indicates

A)something is faulty.
B)a time delay for current attaining its average speed.
C)increased temperature means increased resistance.
D)nothing of interest

Answer 3

increased temperature means increased resistance.

Question 4

A coulomb of charge flowing in a bulb filament powered by a 6-volt battery is provided with

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

Question 5

A suitable electric pump in an electric circuit is a

A)chemical battery.
B)generator.
C)both of these
D)neither of these

Question 6

Just as a sustained flow of water in a hydraulic circuit needs a pump, in electric circuits the flow of charge needs

A)current.
B)voltage.
C)resistance.

Question 7

An ampere is a unit of electric

A)current.
B)voltage.
C)resistance.

Question 8

Voltage is most similar to

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

Question 9

Electrons flow in a wire when there is

A)an imbalance of charges in the wire.
B)a potential difference across its ends.
C)a difference in potential energy across its ends.
D)none of the above

Question 10

To think of electric potential difference we are thinking about

A)current.
B)voltage.
C)resistance.

Question 11

If you stretch a copper wire so that it is thinner, the resistance between its ends

A)decreases.
B)remains unchanged.
C)increases.

Question 12

Just as water flows from a region of high pressure to a region of low pressure, electric charge flows from a region of

A)high electric pressure to a region of low electric pressure.
B)high potential energy to a region of low potential energy.
C)deep to shallow regions.
D)all of the above

Question 13

Two light bulbs are connected to a battery, one at a time. The bulb that draws more current has the

A)lower resistance, and is brightest.
B)lower resistance, but is dimmer.
C)higher resistance, and is brightest.
D)higher resistance, but is dimmer.
E)none of the above

Question 14

Which statement is correct?

A)charge flows in a circuit
B)voltage flows in a circuit
C)resistance flows in a circuit
D)all of the above

Question 15

Heat a copper wire and its electric resistance

A)decreases.
B)remains unchanged.
C)increases.

Question 16

If two copper wires of the same length have different thickness, then the thicker wire has

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

Question 17

Just as in hydraulic circuits there is water pressure, in electric circuits there is

A)current.
B)voltage.
C)resistance.

Question 18

The current produced by voltage in a circuit is impeded by

A)electric barriers.
B)closed switches.
C)electric resistance.
D)none of the above

Question 19

It is correct to say that in electric circuits

A)charge flows through a circuit.
B)flowing charge is current.
C)voltage is applied across a circuit.
D)voltage is the ratio of energy per charge.
E)all of the above

Question 20

Electric resistance in our skin is lowered when our skin is

A)moist.
B)dry.
C)none of the above

Question 21

The source of electrons in a simple electric circuit is

A)the voltage source.
B)energy stored in the voltage source.
C)energy released by the voltage source.
D)the electrical circuit itself.
E)none of the above

Question 22

Two lamps with different filament thicknesses, and therefore different resistances, are connected in series. Greater current is in the lamp with the

A)thick filament.
B)thin filament.
C)same in each

Question 23

The number of electrons delivered daily to an average American home by an average power utility in the early 21^st century was

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

Question 24

Electrons flow in an electrical circuit by

A)being bumped by other electrons.
B)colliding with molecules.
C)interacting with an established electric field.
D)none of the above

Question 25

The source of electrons that illuminate a common lamp in your home is

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

Question 26

A capacitor is useful in

A)boosting the energy output of a circuit.
B)increasing the current in a resistor.
C)smoothing pulsed current.
D)changing dc to ac in a circuit.
E)increasing or decreasing voltage.

Question 27

Direct current is normally produced by a

A)battery.
B)generator.
C)both of these
D)neither of these

Question 28

An electric diode is useful for

A)storing electrical energy.
B)boosting voltage.
C)limiting current.
D)voltage modification.
E)changing ac to dc.

Question 29

Electrons that are energized to glow in the filament of a common ac lamp are

A)supplied by a wall outlet.
B)supplied by a wall outlet, which in turn are supplied by your power company.
C)electrons already in the filament.
D)none of the above

Question 30

The voltage across a 10-ohm resistor carrying 5 A is

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

Question 31

For electric current in the home, your power company supplies

A)energy.
B)electrons.
C)both of these
D)neither of these

Question 32

Current that is typically 60 hertz is

A)direct current.
B)alternating current.
C)either of these
D)neither of these

Question 33

The cause of electrical shock is predominantly

A)excess current.
B)excess voltage.
C)reduced resistance.
D)none of the above

Question 34

The resistance of a filament that carries 2 A when a 10-V potential difference across it is

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

Question 35

The current in two identical light bulbs connected in series is 0.25 A. The voltage across both bulbs is 110 V. The resistance of a single light bulb is

A)22 ohms.
B)44 ohms.
C)220 ohms.
D)440 ohms.
E)none of the above

Question 36

Alternating current is normally produced by a

A)battery.
B)generator.
C)both of these
D)neither of these

Question 37

The source of energy that illuminates a lamp in your home is

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

Question 38

If an electric toaster rated at 110 V is accidently plugged into a 220-V outlet, the current drawn by the toaster will be

A)half its normal value.
B)the same as its normal value.
C)twice its normal value.
D)none of the above

Question 39

Current in a conductor can be increased by

A)increasing the voltage across it.
B)reducing its resistance.
C)both of these
D)neither of these

Question 40

When Eddie Electron experiences an electrical shock, the source of electrons composing the shock is

A)the ground beneath Eddie's feet.
B)Eddie's body.
C)the power plant.
D)whatever electric device being handled.
E)electric field in the air.

Question 41

The electric field established by a generator in an ac circuit

A)increases via the inverse-square law.
B)changes magnitude and direction with time.
C)acts in one direction.
D)is non-existent.
E)none of the above

Question 42

One kilowatt-hour is a unit of

A)energy.
B)power.
C)voltage.
D)current.
E)resistance.

Question 43

A lamp rated at 120W 120V has a filament resistance of

A)1 ohm.
B)60 ohms.
C)100 ohms.
D)144 ohms.
E)none of the above

Question 44

When we say an appliance "uses up electricity," we mean

A)current disappears.
B)electric charges are dissipated.
C)voltage is lowered.
D)electric energy dissipates into heat.

Question 45

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)need more information

Question 46

A power line with a resistance of 2 ohms carries a current of 80 A. The power dissipated in the line is

A)40 W.
B)160 W.
C)320 W.
D)12,800 W.
E)none of the above

Question 47

The drift speed of electrons that compose current in a flashlight is about

A)the speed of sound waves in metal.
B)the speed of light.
C)1000 cm/s.
D)less than 1 cm/s.
E)any of the above under different conditions.

Question 48

In units of measurement, power in watts is equal to

A)amperes x ohms.
B)amperes x volts.
C)amperes/second.
D)volts/second.
E)none of the above

Question 49

Although electrons in metal move in haphazard directions at many times the speed of sound, the drift speed of electrons that compose electric current is

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

Question 50

One joule per coulomb is a unit of

A)energy.
B)power.
C)voltage.
D)current.
E)resistance.

Question 51

A 100-W lamp glows brighter than a 25-W lamp. The current drawn by the 100-W lamp is

A)less.
B)greater.
C)the same.

Question 52

The electric field established by a battery in a dc circuit

A)increases via the inverse-square law.
B)changes magnitude and direction with time.
C)acts in one direction.
D)is non-existent.
E)none of the above

Question 53

The power consumed by a device drawing 0.8 A when connected to 120 V is

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

Question 54

A 100-W lamp glows brighter than a 25-W lamp. The electrical resistance of the 100-W lamp is

A)less.
B)greater.
C)the same.

Question 55

Power is defined as the energy expended per unit of time. When translated to electrical terms, power is equal to

A)current multiplied by resistance.
B)current multiplied by voltage.
C)current divided by time.
D)voltage divided by time.
E)none of the above

Question 56

When a 12-V battery powers a single 6-ohm lamp,

A)2 joules flow in the lamp each second.
B)6 joules flow in the lamp each second.
C)12 joules flow in the lamp each second.
D)none of the above

Question 57

A 60-W light bulb connected to a 120-V source draws a current of

A)0.25 A.
B)0.5 A.
C)2.0 A.
D)4.0 A.
E)more than 4 A.

Question 58

The energy dissipated in a light bulb in a circuit is provided by the

A)lamp filament itself.
B)wires leading to the lamp.
C)voltage source.
D)none of the above

Question 59

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

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

Question 60

One kilowatt is a unit of

A)energy.
B)power.
C)voltage.
D)current.
E)resistance.

Question 61

A heater draws 20A when connected to a 110-V line. If the electric power costs 20 cents per kilowatt hour, the cost of running the heater for 10 hours is

A)$0.44.
B)$1.10.
C)$4.40.
D)$11.00.
E)none of the above

Question 62

A 60-W and a 100-W light bulb are connected in series to a 120-V outlet. Which bulb draws more current?

A)60-W bulb
B)100-W bulb
C)both the same.

Question 63

An electric heater is rated 300W 110V. The safety fuse in the circuit can withstand 15 A of current. How many heaters can be safely operated in the circuit?

A)2
B)3
C)4
D)5
E)more than 5

Question 64

The amount of current in a CFL rated 23W 120V is about

A)0.2A.
B)5.2A.
C)more than 5.2A.

Question 65

The amount of current in an LED bulb rated 10.5W 120V is

A)less than 1 A.
B)about 1 A.
C)more then 1 A.

Question 66

A 60-W and a 100-W light bulb are connected in parallel to a 120-V outlet. Which bulb draws more current?

A)60-W bulb
B)100-W bulb
C)both the same.

Question 67

Compared with the amount of current in the filament of a lamp, the amount of current in the connecting wires is

A)definitely less.
B)often less.
C)actually more.
D)the same.
E)incredibly, all of the above

Question 68

Modern automobile headlights are connected in

A)parallel.
B)a perpendicular orientation.
C)series.
D)none of the above

Question 69

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)none of these

Question 70

A 60-W and a 100-W light bulb are rated at 120V. Which bulb has a higher resistance?

A)60-W bulb
B)100-W bulb
C)both the same.

Question 71

The amount of current in an incandescent bulb rated 75W 120V is about

A)0.4 A.
B)0.6 A.
C)1.2 A.
D)more than 1.2 A.

Question 72

A lamp rated 23W 120V means that it will deliver 23 W

A)when the voltage across it is 120 V.
B)whether or not it is connected to 120 V.
C)as long as the current is ac.
D)none of the above

Question 73

In a circuit powered by a battery, charge

A)flows through the battery.
B)is energized by the battery.
C)both of these
D)neither of these

Question 74

When a pair of identical lamps are connected in parallel

A)voltage across each is the same.
B)current in each is the same.
C)power dissipated in each is the same.
D)all of the above

Question 75

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)none of these

Question 76

By convention, the direction of current in a circuit is

A)from the positive terminal of a source to the negative terminal.
B)the direction in which positive charge flows.
C)both of these
D)neither of these

Question 77

If you wish to keep chicken warm in a shed on a cold night, the best lamp to use is

A)an incandescent lamp.
B)a fluorescent lamp.
C)an LED lamp.
D)a CFL lamp.

Question 78

The brightness of a lamp is directly related to its

A)brand.
B)place of manufacture.
C)power rating.
D)all of the above
E)none of the above

Question 79

On some early automobiles both headlights failed when one bulb burned out. The headlights were likely connected in

A)parallel.
B)perpendicular.
C)series.
D)haste.

Question 80

The current drawn by a 1200-W toaster connected to 120 V is 10 A. The resistance of the toaster coils is

A)6 ohms.
B)12 ohms.
C)18 ohms.
D)none of the above