Q&A Hero

Q: When we consider the distance a pendulum swings to and fro we're talking about the pendulum's A) frequency. B) period. C) wavelength. D) amplitude.

Q: The vibrating system with the greatest frequency has the A) shortest period. B) longest period. C) both of these D) none of the above

Q: When we consider the time for an oscillating system to make a vibration we're talking about A) frequency. B) period. C) wavelength. D) amplitude.

Q: When we consider how frequently an oscillating system vibrates we're talking about A) frequency. B) period. C) wavelength. D) amplitude.

Q: A wave is a vibration in A) space. B) time. C) both of these D) none of the above

Q: A wiggle in time is a A) vibration. B) wave. C) both of these D) none of the above

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

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

Q: 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.

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

Q: 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.

Q: 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

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

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

Q: 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.

Q: 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

Q: 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

Q: 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

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

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

Q: 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

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

Q: 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.

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

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

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

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

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

Q: 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

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

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

Q: 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.

Q: 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

Q: 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.

Q: 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.

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

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

Q: 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

Q: 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

Q: 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

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

Q: 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

Q: 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

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

Q: 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

Q: 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

Q: 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

Q: 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

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

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

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

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

Q: 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.

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

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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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.

Q: 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

Q: 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

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

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

Q: 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.

Q: 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

Q: 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.

Q: 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

Q: 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.

Q: 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

Q: 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

Q: 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