Quiz 9: Magnetism and Electromagnetic Induction

The rule for the interaction of magnetic poles is similar to the rule for electric A)circuits. B)polarization. C)charges.

Unlike electric charges,magnetic poles cannot be A)located. B)isolated. C)destroyed.

Like kinds of magnetic poles repel while unlike kinds of magnetic poles A)attract. B)repel also. C)may attract or repel.

Every magnet contains at least A)one pole. B)two poles. C)four poles.

Refrigerator magnets are typically A)short range. B)long range. C)none of these

If you break a bar magnet in half you'll A)destroy its magnetic properties. B)have two magnets. C)have four magnets. D)none of the above

Magnet A has twice the magnetic field strength of magnet B and pulls on magnet B with a force of 100 N.The amount of force that magnet A exerts on magnet B is A)about 50 N. B)exactly 100 N. C)more than 100 N. D)not enough information

Compared with the huge force that attracts an iron tack to a strong magnet,the force that the tack exerts on the magnet is A)relatively small. B)equally huge. C)not enough information

The ultimate source of all magnetism is A)tiny bits of iron. B)tiny domains of aligned atoms. C)ferromagnetic materials. D)moving electric charge.

A strong magnetic field easily penetrates A)human flesh. B)plastic coatings. C)both of these D)none of the above

Every spinning electron is A)electrically charged. B)a tiny magnet. C)both of these D)none of the above

Surrounding every stationary electron is A)a magnetic field. B)an electric field. C)both of these D)neither of these

Surrounding every moving electron is A)a magnetic field. B)an electric field. C)both of these D)neither of these

Magnetism is due to the motion of electrons as they A)move around the nucleus. B)spin on their axes. C)both of these D)neither of these

An iron rod becomes magnetic when A)opposite ions accumulate at each end. B)its atoms are aligned. C)the net spins of many internal electrons are aligned. D)its electrons stop moving and point in the same direction.

A compass needle in a magnetic field experiences A)a torque. B)a net force. C)both of these D)none of the above

Wood does not have magnetic properties because it contains no A)iron or other metals. B)magnetic domains. C)moving electrons. D)none of the above

Magnetic domains normally occur in A)iron. B)copper. C)silver. D)all of the above E)none of the above

A magnet will become weaker if it is A)dropped on a hard surface. B)held in a hot flame. C)either D)neither

An iron nail is attracted A)more strongly to the north pole of a magnet. B)more strongly to the south pole of a magnet. C)equally to either pole of a magnet. D)none of the above

A bar magnet that holds a chain of nails illustrates A)magnetic field displacement. B)magnetic induction. C)electromagnetic induction.

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)either of these D)neither of these

When a bar magnet is broken in half,the strength of the four new poles relative to pole strength before breaking is A)less than half. B)half. C)the same. D)somewhat more.

The magnetic field lines generated by a bar magnet A)are external only. B)are both external and internal to the magnet. C)follow an inverse-square law. D)none of the above

The magnetic field lines about a straight current-carrying wire are A)circular. B)radial. C)elliptical. D)spiral.

Magnetic field lines about a current-carrying wire A)extend radially from the wire. B)circle the wire in closed loops. C)both of these D)none of the above

When current reverses direction in a wire,the surrounding magnetic field A)also reverses direction. B)becomes momentarily stronger. C)contracts. D)expands.

When a current-carrying wire is bent into a loop,its magnetic field inside the loop A)weakens. B)becomes concentrated. C)cancels. D)none of the above

As the number of loops in a current-carrying wire coil is increased,the magnetic field becomes A)more spread out. B)more stable. C)stronger. D)weaker. E)none of the above

The magnetic field strength inside a current-carrying coil will be greater if the coil encloses A)a vacuum. B)a wooden rod. C)a glass rod. D)an iron rod. E)none of the above

A magnetic field exists in a current-carrying coil of wire A)if it contains a piece of iron. B)with or without a contained piece of iron. C)only if the current changes.

The magnetic field inside a current-carrying coil increases when A)current is increased. B)the number of loops of wire in the coil increases. C)an iron core is inserted. D)all of the above E)none of the above

A common electromagnet consists of a A)bar magnet that carries an electric current. B)current-carrying wire coil. C)current-carrying coil with a piece of iron inside.

Superconducting electromagnets A)account for cases of magnetic levitation. B)are characterized by easy penetration of external magnetic fields. C)both of these D)none of the above

A superconducting electromagnet makes use of A)zero resistance coils of wire. B)super-high temperatures. C)high-speed electrons. D)close packing of high-density magnetic domains.

The lift experienced by Maglev trains is due to magnetic A)attraction. B)repulsion. C)dipoles.

Moving electric charges will interact with A)an electric field. B)a magnetic field. C)both of these D)none of the above

Into which stable force field can a proton be placed at rest without being accelerated? A)magnetic field B)electric field C)both of these D)none of the above

Maximum magnetic force occurs when electrons move A)in the same direction as the magnetic field. B)opposite to the magnetic field direction. C)perpendicular to the magnetic field direction. D)at non-right angles to the magnetic field direction. E)none of the above

The minimum or no magnetic force on a moving electron occurs for motion A)parallel to the magnetic field. B)perpendicular to the magnetic field. C)at non-right angles to the magnetic field direction.

No magnetic force acts on a current carrying wire when it A)carries a very small current. B)is perpendicular to the magnetic field. C)either or both of these D)none of the above

A magnetic force acts most strongly on a current carrying wire when it A)carries a very large current. B)is perpendicular to the magnetic field. C)either or both of these D)none of the above

When an electron passes through the magnetic field of a horseshoe magnet,the electron's A)speed is increased. B)direction of motion is changed. C)both of these D)none of the above

An electron beam directed through a magnetic field A)may be deflected. B)may experience a force. C)both of these D)neither of these

No net force acts on a loop of wire in a magnetic field when A)no current is in the loop. B)no magnetic field lines pass through the loop. C)both of these D)neither of these

If a magnet produces a force on a current-carrying wire,the wire A)produces a force on the magnet. B)may or may not produce a force on the magnet. C)neither of these

Near our planet Earth are A)cosmic rays. B)magnetic fields. C)both of these D)none of the above

Earth's magnetic field affects cosmic rays by A)deflecting them. B)slowing their speeds. C)destroying them. D)absorbing them.

The intensity of cosmic rays bombarding the Earth's surface is greatest at A)the poles. B)mid-latitudes. C)the equator. D)no particular locations.

A galvanometer measures A)magnetic fields. B)electric current. C)electric voltage. D)none of the above

A galvanometer is a useful device in electric A)electromagnets. B)transformers. C)generators and motors. D)meters. E)none of the above

A galvanometer calibrated to read current is A)an ammeter. B)a voltmeter. C)an ohm meter. D)none of the above

A galvanometer calibrated to read potential difference is A)an ammeter. B)a voltmeter. C)an ohm meter. D)none of the above

Since magnetic force on a moving electron is always perpendicular to its direction of motion,magnetic force is unable to change an electron's A)speed. B)direction. C)speed and direction. D)none of the above

Which force field can increase a moving electron's speed? A)electric field B)magnetic field C)both of these D)none of the above

Which force field can both accelerate an electron and change its speed? A)electric field. B)magnetic field. C)both of these D)none of the above

Which of these singly ionized atoms of the same speed will curve most in a magnetic field? A)helium B)iron C)uranium D)all the same

In which of these locations is cosmic ray intensity greatest? A)Mexico City B)Toronto C)Singapore D)all about the same

The discovery of electromagnetic induction is credited to A)Joseph Henry in America. B)Michael Faraday in England. C)both of these D)none of the above

Faraday's law describes A)electromagnetic induction. B)the connection between current,voltage,and resistance. C)the attraction and repulsion of magnetic poles. D)the force between magnetic poles. E)all of the above

Electromagnetic induction is employed in A)credit card readers. B)computers. C)mobile phones. D)all of the above E)none of the above

Electromagnetic induction occurs in a coil when there is a change in A)electric field intensity. B)magnetic field intensity. C)voltage. D)the coil's polarity. E)none of the above

Voltage can be induced in a wire by A)moving the wire near a magnet. B)moving a magnet near the wire. C)changing the current in a nearby wire. D)all of the above E)none of the above

When a change of magnetic field occurs in a closed loop of wire, A)a voltage is induced in the wire. B)current is made to flow in the loop of wire. C)electromagnetic induction occurs. D)all of the above E)none of the above

Changing the magnetic field intensity in a copper coil induces A)current. B)voltage. C)both of these D)none of the above

Thrust a magnet into a coil of wire and you'll induce A)voltage. B)current. C)both of these D)none of the above

When a bar magnet is thrust into a coil of wire,a greater voltage is induced with A)a greater number of loops in the coil. B)faster thrusting motion. C)a stronger bar magnet. D)all of the above

When a bar magnet is thrust at the same speed into a coil having twice the number of loops,the induced voltage is A)half. B)the same,no different. C)twice as much. D)four times as much. E)none of the above

The frequency with which a magnet plunges into and out of a wire coil equals the frequency of the induced A)voltage. B)current. C)both of these D)none of the above

When a bar magnet is thrust into a coil of wire,the coil A)attracts the magnet as it enters. B)repels the magnet as it enters. C)both of these D)none of the above

A copper ring can be made to levitate about the extended bar of an electromagnet because the magnetic field induced in the ring A)remains strong and steady. B)opposes the field producing it. C)is attracted to the top end of the bar. D)none of the above

The amount of current produced by electromagnetic induction depends on the A)amount of induced voltage. B)resistance of the circuit to which it is connected. C)both of these D)none of the above

The metal detectors that travelers walk through at airports operate via A)Ohm's law. B)Faraday's law. C)Coulomb's law. D)Newton's laws.

Metal detectors that locate metal beneath sand on a beach are activated by A)electric fields. B)magnetic fields. C)electromagnetic induction. D)alternating current.

Fred swings a sheet of copper in pendulum fashion between the poles of a strong magnet.The sheet slows in entering the magnetic field because the field A)induces swirling currents in the copper and accompanying magnetic fields that resist motion. B)experiences both air and magnetic friction. C)is repelled by free electrons in the copper. D)none of the above

If you drop a bar magnet in a vertical copper pipe it will fall slowly because A)of air resistance. B)it induces a magnetic field in the pipe that resists motion of the magnet. C)the copper is a good conductor of both electricity and magnetism. D)of electron repulsion.

Alternating current is normally produced by a A)battery. B)generator. C)both of these D)none of the above

The current produced by a common generator is A)dc. B)ac. C)neither of these

Which of these statements is true? A)a battery produces dc and a generator produces ac B)a battery produces ac and a generator produces dc C)a battery and a generator produce dc D)a battery and a generator produce ac

Compared with a motor,a generator is A)one and the same. B)its opposite. C)of an entirely different design.

An electric motor and electric generator are A)very similar devices. B)entirely different devices. C)none of the above

An electric motor and electric generator differ in A)the roles of input and output. B)basic construction. C)size. D)quality.

A device that transforms electrical energy to mechanical energy is a A)generator. B)motor. C)transformer. D)magnet. E)none of the above

A device that transforms mechanical energy to electrical energy is a A)generator. B)motor. C)transformer. D)magnet. E)none of the above

Voltage produced by a generator alternates because A)it produces pulses of current. B)the magnetic field that produces it alternates. C)alternations in the mechanical energy input. D)effectively it is an ac motor in reverse. E)the current it produces alternates.

A turbogenerator produces A)energy. B)power. C)neither,but transforms energy from one form to another. D)none of the above

Disregarding the effects of friction,a cyclist will coast farther when a lamp powered by a wheel generator is A)of low wattage. B)of high wattage. C)burned out. D)none of the above

Power is the rate at which A)energy is transferred. B)voltage can be changed. C)current can be induced.

The rate at which energy is transferred is A)power. B)electromagnetic induction. C)transformation. D)none of the above

An electric generator A)can create enough energy to light cities. B)can convert mechanical energy to electric energy. C)needs no energy source. D)all the above E)none of the above

The sloshing of electrons inside a generator needs A)an outside source of energy. B)a copper lattice. C)positive ions. D)none of the above

The energy source for a generator may be A)a waterfall. B)steam from a turbine. C)wind. D)any of these E)none of the above

A topic that most underlies electrical studies and all of physics is A)Newton's laws of motion. B)the conservation of momentum. C)the conservation of energy.

The rate at which a transformer transfers energy is called A)electromagnetic induction. B)transformer efficiency. C)power.

A transformer requires A)alternating voltage. B)direct current. C)both of these D)none of the above

A transformer actually transforms A)energy from one value of voltage to another. B)magnetic and electric field lines. C)generators into motors. D)motors into generators. E)all of the above

Compared with the power input to an ideal transformer,the power output is A)greater. B)less. C)either greater or less. D)the same.

Compared with the voltage input to a transformer,the voltage output can be A)greater. B)less. C)greater or less.

Transformers use ac so there will be the required A)transfer of energy from coil to coil. B)voltage for transformation. C)change in magnetic field for operation. D)change in input current. E)magnetic field intensities.

An efficient step-up transformer increases A)power. B)energy. C)both of these D)none of the above

An efficient step-down transformer decreases A)current. B)voltage. C)power. D)energy. E)all of the above

The principal difference between a step-up and step-down transformer is A)step-up transformers can handle more current. B)different geometries. C)different ratios of turns for each set of loops or coils. D)none of the above

Compared with the current in the primary coil of a transformer,the current in the secondary coil A)is greater. B)is less. C)can be greater or less. D)none of the above

The voltage across the input terminals of a transformer is 110 V.The primary coil has 50 loops and the secondary has 25 loops.The output is A)25 V. B)55 V. C)110 V. D)220 V. E)none of the above

The voltage across the input terminals of a transformer is 110 V.The primary coil has 50 loops and the secondary coil has 100 loops.The output is A)25 V. B)55 V. C)110 V. D)220 V. E)none of the above

A certain transformer doubles input voltage.If the primary coil has 10 A of current,then the current in the secondary coil is A)2 A. B)5 A. C)10 A. D)25 A. E)none of the above

An ideal transformer has 50 turns in its primary and 250 turns in its secondary.When 12-V ac is connected to the primary,the voltage available to the secondary is A)5 V. B)10 V. C)30 V. D)60 V.

An ideal transformer has 50 turns in the primary and 500 turns in the secondary.An input of 12 V will produce an output of A)12 V. B)120 V. C)1200 V. D)none of the above

If the primary of a transformer were connected to a dc power source,the transformer would have a voltage output A)at a higher efficiency than with an ac source. B)the same as its input. C)that is also dc. D)only briefly while being connected or disconnected. E)none of the above

A current of 4 A exist in the primary coil of a transformer powered with 110 V.What is the power output of the secondary coil? A)27.5 W B)110 W C)440 W D)880 W E)not enough information

A transformer for a laptop computer converts a 120-V input to a 24-V output.Compared with the number of turns on the primary coil,the secondary has A)1/5 as many turns. B)5 times as many turns. C)the same number of turns. D)none of the above

An electronic game requires 6 V for operation.With a transformer it can be powered by a 120-V outlet.If the primary has 500 turns,the secondary has A)4 turns. B)25 turns. C)50 turns. D)more than 50 turns. E)none of the above

A transformer has an input of 6 V and an output of 42 V.If the input is changed to 12 V,the output would be A)12 V. B)48 V. C)84 V. D)more than 84 V. E)none of the above

The rapid change of a magnetic field induces A)an electric field. B)a stronger magnetic field. C)both of these D)none of the above

The rapid change of an electric field induces A)a stronger electric field. B)a magnetic field. C)both of these D)none of the above

Maxwell's counterpart to Faraday's law simply states that A)each change in one field induces the other. B)electric and magnetic fields are one and the same. C)induced fields are parallel to each other. D)all of the above

In the field induction credited to Maxwell,wires A)can be insulated or non-insulated. B)are minimized. C)are not needed.

The induced electric and magnetic fields of Maxwell are A)parallel to each other. B)perpendicular to each other. C)non-directional.

Induced electric and magnetic fields produce A)stronger electric or magnetic field. B)higher voltages produced by Faraday induction. C)both of these D)none of the above

Electric and magnetic fields combine to produce A)sound. B)light. C)both of these D)none of the above

The frequency of a generated electromagnetic wave matches the A)field strength of the fields. B)energy of the fields. C)frequency of vibrating charges that produced it. D)frequency of domains in the magnetic part of the wave.

What any type of field generation cannot create is A)light. B)electromagnetic waves. C)energy.

A friend says that changing electric and magnetic fields underlie the production of light. A)agree with your friend B)disagree with your friend C)find a new friend

What is the cause of a magnetic field about a permanent magnet and about a current-carrying wire?

Distinguish between a common bar magnet and an electromagnet.

What happens to a current-carrying wire in a magnetic field? How does orientation of the wire make a difference?

State and explain Faraday's law of induction.

How are electric motors and electric generators similar? Different?

What correction do you suggest to a friend who states that a step-up transformer boosts energy,while a step-down transformer reduces energy in a circuit?

What is the connection,if any,between electromagnetic induction and sunshine?