Physics test 3

require an energy source

A feature common to all generators is that they _______. produce energy produce energy and power produce power require an energy source

potential difference across the ends of the wire

A flow of electric charge in a wire normally requires a _______. voltage source pump potential difference across the ends of the wire sustained energy difference across the ends of the wire

periodically alternates

A generator normally produces ac because the magnetic field experienced by interior coils _______. experiences force produces electromagnetic induction remains steady periodically alternates

B

A positive ion has more A.electrons than protons. B.protons than electrons. C.protons than neutrons. D.neutrons than protons. E.electrons than neutrons.

may be electrically charged

A wire that carries an electric current is electrically charged. is never electrically charged. may be electrically charged.

5 coulombs per second

An electric current of 5 amperes in a wire carries _______. 5 joules per ohm 5 coulombs per joule 5 coulombs per second 5 volts per coulomb

A

An uncharged pith ball is suspended by a nylon fiber. When a negatively charged rubber rod is brought nearby, without touching it, the pith ball A.becomes polarized. B.is repelled by the rod. C.is unaffected. D.becomes charged by induction. E.None of the above choices are correct.

all of the above

Between a pair of equal and opposite charges, field lines are more concentrated closer to the charges. vectors, with patterns that stem from the inverse-square law. directed from positive to negative. all of the above none of the above

less current

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

much the same with small modifications

Compared with a simple galvanometer, an electric motor is _______. much the same with small modifications different in that it is a source of voltage fundamentally different a complicated voltmeter

loose outer electrons

Conducting materials are composed of atoms with strong cohesive forces between them. loose outer electrons. vastly more charge than insulators. excess neutrons compared with protons.

9

Consider the power dissipated by the two circuits in the video. The ratio of power dissipation in the parallel circuit to that in the series circuit is 1/9 1/3 3 1 9

charge

Electric potential, measured in volts, is the ratio of electric energy to the amount of electric voltage. charge. current. resistance. none of the above

energy dissipates

Electric power in a circuit is the rate at which _______. energy dissipates wattage dissipates voltage dissipates current dissipates

there is relative motion of hte loop and wire or when current changes in the loop when near a magnet

Electromagnetic induction occurs in a loop of wire only when _______. a magnet moves near the loop the loop moves near a magnet current changes in a loop near a magnet there is relative motion of the loop and wire or when current changes in the loop when near a magnet

zero

Electrons in the filament of a lamp that carries ac have a net speed that is _______. about the speed of sound very low, about a snail's pace zero about the speed of light

a magnetic field in the loop changes

Faraday's law states that induced voltage in a loop of wire depends on the rate at which _______. current is made to oscillate within the loop voltage changes a magnet is thrust into the loop a magnetic field in the loop changes

increases

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

negatively charged

If you comb your hair and the comb becomes positively charged, then your hair becomes uncharged. positively charged. negatively charged.

C. electrons that surround the nucleus

In an electrically neutral atom the number of protons in the nucleus is equal to the number of A. neutrons in the nucleus. B. both electrons and neutrons. C. electrons that surround the nucleus. D. none of the above

change in magnetic field intensity

In order for electromagnetic induction to occur in a circuit, there must be a _______. meter to measure current coil of wire battery or some other voltage source change in magnetic field intensity

aligned iron atoms

Magnetic domains are composed of clustered _______. electrically charged iron atoms crystals of iron ions iron atoms in random directions aligned iron atoms

circle the wire in closed loops

Magnetic field lines about a current-carrying wire circle the wire in closed loops. extend radially from the wire. Choices A and B are both correct. None of the above choices are correct.

north to south

Outside a magnet, magnetic field lines are conventionally drawn from north to south. south to north. either way

equator

The cosmic rays deflected most by Earth's magnetic field are above the _______. mid longitudes of Earth north and south poles lower levels of the atmosphere equator

twice as long

The electric resistance in a length of wire is doubled when the wire is _______. half as long doubled in temperature properly insulated twice as long

A

The electrical force between charges depends only on the charges' A.magnitude and separation distance. B.separation distance. C.magnitude. D.None of the above choices are correct.

A

The electrical force between charges is strongest when the charges are A.close together. B.far apart. C.The electric force is constant everywhere.

the electric field

The entity that travels at about the speed of light in an electric circuit is _______. the electric field current voltage the voltage and electric field, but not current

the electric field

The entity that travels at about the speed of light in an electric circuit is _______. voltage current the electric field the voltage and electric field, but not current

negative

The figure shows the path of a charged particle moving in a magnetic field directed into the screen. The figure shows the path of a charged particle moving in magnetic field B directed into the screen. The particle moves clockwise along the circular path. What is the particle's charge? negative positive neutral

pependicular in direcation to the magnetic field

The force that acts on a current-carrying wire placed in a magnetic field is _______. perpendicular in direction to the magnetic field opposite in direction to the magnetic field parallel in direction to the magnetic field perpendicular or parallel to the magnetic field, depending on the orientation of the field

perpendicular in direction to the magnetic field

The force that acts on an electron traveling in a magnetic field is _______. parallel in direction to the magnetic field opposite in direction to the magnetic field perpendicular in direction to the magnetic field perpendicular or parallel to the magnetic field, depending on the orientation of the field

like poles repel each other and opposite poles attract

The fundamental rule for the attraction and repulsion of magnets is _______. magnetic forces follow the inverse-square law magnetic poles attract other magnetic poles opposite charges attract each other and like charges repel Like poles repel each other and opposite poles attract.

similar to that of an interior bar magnet

The magnetic field about Earth takes a shape _______. similar to that of an interior bar magnet of the field about a straight length of current-carrying wire of an interior current-carrying coil that conforms to the inverse-square law

circular in shape

The magnetic field about a straight length of current-carrying wire is _______. aligned from north to south poles in the wire circular in shape in accord with the inverse-square law similar to the shape of an electric field about a charged wire

moving electric charge

The source of all magnetism is ferromagnetic materials. tiny domains of aligned atoms. moving electric charge. tiny pieces of iron. none of these

its charges have been rearranged

To say that an object becomes electrically polarized means that it is electrically charged. its internal electric field is zero. it is only partially conducting. its charges have been rearranged. none of the above

F.

Two charged particles attract each other with a force F. If the charges of both particles are doubled, and the distance between them also doubled, then the force of attraction will be F/2. F. 2 F. F/4. none of the above

the wire jumps down

What happens when Dr. Hewitt places a current- carrying wire between the poles of the magnet for the first time? Nothing happens to the wire. The wire jumps down. The wire jumps up.

the wire jumps up

What happens when Dr. Hewitt turns the magnet around and places the current-carrying wire between the poles of the magnet for the second time? The wire jumps up. The wire jumps down. Nothing happens to the wire.

electric motor

What kinds of appliances work on the principle of deflection of a current-carrying wire in a magnetic field? electric generator electric motor both an electric generator and an electric motor

power

What transforms from one coil to another in a transformer is _______. mainly voltage mainly current power electricity

5 ohms

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

D

When a car is struck by lightning, the resulting electric field inside the car is A.small enough to be safe for an occupant inside. B.normally huge for a time longer than the lightning stroke itself. C.normally huge, but for a brief time. D.zero.

work is needed to overcome a resistance to the push

When a magnet is quickly pushed into a coil of wire connected to a circuit, _______. no pushing effort is required resistance via Ohm's law is experienced work is needed to overcome a resistance to the push the magnet is drawn farther into the coil

the coil becomes a stronger electromagnet

When an iron rod is placed inside a current-carrying coil of wire, _______. only then does the coil have a north and south magnetic pole more current is required to increase its magnetic strength the coil becomes a stronger electromagnet the coil becomes an electromagnet

continue growing as brightly

When the filament breaks in one lamp in a parallel circuit, lamps in other branches of the circuit normally _______. continue glowing as brightly continue glowing, but more dimly go out absorb energy from the damaged lamp

go out

When the filament breaks in one lamp in a series circuit, other lamps in the circuit normally _______. continue glowing, but more dimly absorb energy from the damaged lamp go out continue glowing as brightly

more than the resistance of either lamp

When two lamps are connected in series to a battery, the electrical resistance that the battery senses is more than the resistance of either lamp. less than the resistance of either lamp. none of these

electrons already in your body

When your body undergoes electric shock, the source of moving electrons is _______. moisture between you and a voltage source the object making electrical contact electrons already in your body mainly from the ground