PHY 102 Ch. 8

In a circuit consisting of two lamps connected in series, if the current in one lamp is 1 A, what is the current in the other lamp?

1 A

An electron is pushed into an electric field where it acquires a 1-V electric potential. If two electrons are pushed the same distance into the same electric field, the electric potential of both electrons is 2 V. 1 V. 4 V. 0.5 V. 0.25 V.

1 V.

A pair of 60-W and 100-W incandescent lamps are intended for 120-V operation. Which lamp draws more current? 100-W lamp 60-W lamp both the same

100-W lamp

A power line with a resistance of 2 ohms draws a current of 80 A. The power dissipated in the line is 12,800 W. 320 W. 160 W. 40 W. none of the above

12,800 W.

Is this bulb designed for use in a 120- circuit or a 220- circuit? 120-V 220-V

120-V

Two charges separated by 1 m exert a 1.0-N force on each other. If the charges are pushed to 0.25-m separation, the force on each charge will be 1 N. 4 N. 8 N. 2 N. 16 N.

16 N.

A pair of 1-ohm resistors connected in series has a combined resistance of 1 ohm. 2 ohms. 1/2 ohm. none of the above

2 ohms.

Find the current in a 280-W bulb connected in a 120-V circuit.

2.3 A

The power dissipated in a 4-ohm resistor carrying 3 A is 18 W. 36 W. 48 W. 7 W. not enough information

36 W.

An electric toy draws 0.52 A from a 70-V outlet. Find the power that the toy consumes.

36.4 W

If 6 V were impressed across the circuit, consisting of two lamps connected in series, and the voltage across the first lamp were 2 V, what would be the voltage across the second lamp?

4 V

A toaster has a heating element of 19 Ω and is connected to a 80-V outlet. Find the current drawn by the toaster. Ohm's law: I =V/R

4.2 A

An electric heater is rated at 300 W when used in a 110-V circuit. The safety fuse in the circuit can accommodate 15 A of current. How many heaters can be safely operated in the circuit? 2 4 5 more than 5 3

5

A resistor carries a current of 2 A when connected to a 10-V battery. What is the resistor's value? 10 ohms 5 ohms more than 20 ohms 2 ohms 20 ohms

5 ohms

How much energy is given to each coulomb of charge passing through a 6-V battery?

6 Joules

A pair of 60-W and 100-W incandescent lamps are intended for 120-V operation. Which lamp has a larger resistance? 60-W lamp 100-W lamp both the same

60-W lamp

What is the power rating of a device that draws 0.8 A when connected to 120 V? 60 W 96 W 12 W 15 W 120 W

96 W

Which statement is correct? Voltage flows in a circuit. A battery is the source of electrons in a circuit. Charge flows in a circuit. All of these answers are correct.

Charge flows in a circuit.

What is the relationship between current, resistance, and voltage difference? Current = Voltage Difference / Resistance Current = Resistance / Voltage Difference Current = Voltage Difference x Resistance

Current = Voltage Difference / Resistance

Is the current in a lightbulb connected to a 220-V source greater or less than that in the same bulb when it is connected to a 110-V source? Current will be greater in the bulb connected to the 220-volt source. Current will be greater in the bulb connected to the 110-volt source. There is no difference between connecting of bulb to the 220-volt source or 110-volt source.

Current will be greater in the bulb connected to the 220-volt source.

Two charged particles repel each other will a force F. If the charge on one particle is doubled and the distance between them is doubled, the force will be F/2. F/4. F. 2 F. none of the above

F/2.

The unit of resistance is named after Georg Simon Ohm. Micheal Faraday. Isaac Newton. Benjamin Franklin. Charles Coulomb

Georg Simon Ohm.

Coulomb's law is similar in form to _______. Newton's law of gravity all of Newton's laws of motion Ohm's law Faraday's law

Newton's law of gravity

A length of wire has resistance R. Two of these same-length wires braided together have a resistance R. 2R. R/2. none of the above

R/2.

How does the current change if you increase the resistance, keeping the voltage difference the same? The current stays the same. The current increases. The current decreases.

The current decreases.

How do the masses of electrons compare with the masses of protons? The masses of electrons are much less than the masses of protons. The masses of electrons are much more than the masses of protons. The masses of electrons and the masses of protons are the same

The masses of electrons are much less than the masses of protons.

How does the resistance of a thick piece of copper wire compare to the resistance of a thin piece of copper wire? The resistance of the thin piece is greater than that of the thick piece. Both the wire and narrow piece of copper provide the same resistance. The resistance of the thick piece is greater than that of the thin piece.

The resistance of the thin piece is greater than that of the thick piece.

The direction of an electric field is defined as the direction of force on a a positively-charged particle. a negatively-charged particle. charged particle.

a positively-charged particle.

Electrons flow in a wire when there is a potential difference across its ends. an imbalance of charges in the wire. more potential energy at one end of the wire than the other end

a potential difference across its ends.

A sustained flow of electric charge requires a potential difference. a resistance. an electric field. electric polarization.

a potential difference.

The flow of charge in a circuit depends on adequate resistance. a potential difference. adequate chemical action. all of the above

a potential difference.

The unit of electric charge, the coulomb, is the charge on a specific large number of electrons. one proton. one electron.

a specific large number of electrons.

Which has greater resistance: a thick wire or a thin wire of the same length? a thin wire a thick wire

a thin wire

A negatively-charged balloon touching a wooden wall pulls positive charge on the wall surface toward it. polarizes molecules in the wall. pushes negative charge in the wall away from it. all of the above none of the above

all of the above

When you purchase a water pipe in a hardware store, water is not included. When you purchase copper wire, electrons already exist in the wire. must be supplied by you, just as water in a water pipe. may fall out, which is why wires are insulated. none of the above

already exist in the wire.

What unit of measurement is represented by coulomb per second?

ampere

What kind of charge does an object acquire when electrons are stripped from it? an object is left with a positive charge an object is left with a negative charge the charge of object remains the same

an object is left with a positive charge

The electric charge on all electrons are identical. vary from atom to atom. vary from ion to ion

are identical.

The source of electrons lighting an incandescent ac light bulb is atoms in the light bulb filament. the power company. the source voltage. the wire leading to the lamp. the electric outlet.

atoms in the light bulb filament.

An electron and a proton attract or repel depending on distance. attract each other. repel each other.

attract each other.

A sustained electric current can be achieved with a battery. generator. both none of the above

both

Every proton in the universe is surrounded by its own gravitational field. electric field. both none of the above

both

Normally a balloon charged to several thousand volts has a relatively small amount of charge. energy. both neither

both

The electric force between charges depends on the separation distance between electric charges. magnitude of electric charges. both none of the above

both

When we talk about electric power we're talking joules per second. watts. both neither

both

The amount of current in a circuit depends on _______. the electrical resistance of the circuit the voltage across the circuit both of these answers neither of these answers

both of these answers

What factors does the resistance offered by a piece of conductor depend upon? both the geometry and the material of the conductor only the geometry of the conductor neither the geometry nor the material of the conductor material of the conductor

both the geometry and the material of the conductor

The electric field in the wires of an ac circuit changes via the inverse square law. is nonexistent. changes direction with time. remains relatively constant. none of the above

changes direction with time.

Which statement is correct? resistance is established across a circuit voltage flows through a circuit current causes voltage charge flows through a circuit

charge flows through a circuit

The electric force between charges is strongest when the charges are close together. far apart. either

close together.

When both voltage and resistance are doubled? current is halved current is doubled current doesn't change

current doesn't change

What is the effect on current through a circuit of steady resistance when the voltage is doubled? current is halved current is doubled current doesn't change

current is doubled

As more lamps are put into a series circuit, the overall current in the power source stays the same. decreases. increases

decreases

Which force binds atoms together to form molecules? electric nuclear centripetal gravitational none of the above

electric

When we say an appliance "uses up" electricity, we actually are saying that electric charges are dissipated. the main power supply voltage is lowered. electrical energy changes to thermal energy. current disappears. electrons are taken out of the circuit and put somewhere else.

electrical energy changes to thermal energy.

The electric current in a copper wire is normally composed of _______. electrons protons ions electrons, protons, and/or ions

electrons

The number of protons in the nucleus of an electrically neutral atom is equal to the number of electrons that surround the nucleus. neutrons in the nucleus. both neithe

electrons that surround the nucleus.

A positive ion has a deficiency of neutrons. electrons. negative ions.

electrons.

To say a circuit is dc is to say that current in the circuit is parallel to the connecting wires. has a single direction. alternates only slowly.

has a single direction.

As more lamps are put into a parallel circuit, the overall current in the power source remains the same. decreases. increases

increases

Heat a copper wire and its electric resistance increases. remains unchanged. decreases

increases

When a steady voltage is across one-half as much resistance, the current remains the same. is quadrupled. is half. is doubled.

is doubled.

What unit of measurement is represented by watt-second?

joule

Electric potential energy is measured in units of joules. watts. volts. amperes. any or all of these

joules

A 100-W lamp glows brighter than a 25-W lamp. The electric resistance of the 100-W lamp is greater. less. the same.

less

Compared to a single lamp connected to a battery, two identical lamps connected in series to the same battery will draw more current. less current. the same current

less current

A compact fluorescent lamp gives more light output for less power. the same power. greater resistance.

less power.

When a light switch is turned on in a dc circuit, the average speed of electrons in the lamp is the speed of sound waves in metal. the speed of light. less than 1 cm/s. 1000 cm/s. dependent on how quickly each electron bumps into the next electron.

less than 1 cm/s.

The current in a 10-ohm resistor is 5 A. What is the voltage across the resistor? 20 V 15 V more than 20 V 10 V 5 V

more than 20 V

As you comb your hair, electrons are rubbed onto the comb, which becomes positively charged. negatively charged. ionized.

negatively charged.

Electric potential and electric potential energy are _______. one and the same in most cases two terms for the same concept both of these answers neither of these answers

neither of these answers

Compared to the work input to charge an electrostatic generator, the energy output is no more. less. more.

no more.

A difference between an insulator and a conductor is that a conductor has more faster moving molecules. electrons than protons. protons than electrons. energy than an insulator. none of the above

none of the above

What is the resistance of a 120-W incandescent lamp connected to a 120-V power supply? 144 ohms 1 ohm 100 ohms 60 ohms none of the above

none of the above

Electric resistance is normally measured in volts. amperes. joules. newtons. none of the above

none of the above, it is measured in ohms

When we say charge is conserved, we mean that charge can _______. take equivalent forms only be transferred from one place to another be saved, like money in a bank be created or destroyed, as in nuclear reactions

only be transferred from one place to another

Electric field lines about a point charge extend outward when the charge is negative. outward when the charge is positive. in circles

outward when the charge is positive.

A water molecule is electrically polarized. insulating. conducting. charged.

polarized

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 then becomes negatively charged. uncharged. positively charged.

positively charged.

When you remove electrons from a metal cup, the cup becomes negatively charged. ionized. positively charged.

positively charged.

What is the relationship among electric power, current, and voltage? power = current + voltage power = current × voltage power = current - voltage power = current ÷ voltage

power = current × voltage

The purpose of a voltage source is to provide an electrical energy sink. pressure. field

pressure.

If you double both the current and the voltage in a circuit, the power _______. quadruples remains unchanged if resistance remains constant halves doubles

quadruples

When the distance between two charges is halved, the electric force between the charges is reduced by one-quarter. quadruples. is half. doubles. none of the above

quadruples.

A pair of positively-charged plastic straws tend to attract each other. neutralize each other. repel each other.

repel each other.

Two lamps, one with a thick filament and one with a thin filament, are connected in parallel to a battery. The voltage is greater across the lamp with the thick filament. thin filament. same for each

same for each

In an electric circuit, the safety fuse is connected to the circuit in parallel. such a way to reduce danger. series

series

A proton and an electron are placed in an electric field. Which undergoes the greater acceleration? the electron the proton both equally neither

the electron

Two charged particles near each other are released. As they move, the force on each particle increases. Therefore, the particles have the opposite sign. not enough information the same sign.

the opposite sign.

Compared to the amount of electric current in the filament of a lamp, the amount of current in the connecting wire is often less. actually more. definitely less. the same. incredibly, all of the above

the same.

Two lamps, one with a thick filament and one with a thin filament, are connected in parallel. The current is greater in the lamp with the thick filament. thin filament. same in each

thick filament.

Compared to the mass of a proton, the mass of the electron is greater. identical. very much less.

very much less.

What unit of measurement is represented by joule per coulomb?

volt

A charged balloon illustrates that something can have a great amount of potential energy and a low voltage. voltage and a small potential energy. both voltage and potential energy. none of the above

voltage and a small potential energy.

Electric potential is measured in units of volts. watts. amperes. joules. any or all of these

volts.

The electric charge on a current-carrying wire is normally zero. the voltage divided by the resistance. equal and opposite to the charge within the wire.

zero

The number of electrons delivered daily by power utilities to an average American home in a typical year in this century is 110. 220. zero. billions of billions. none of the above

zero.