Test 5: Review B

Question 1

The fundamental force underlying all chemical reactions is
A) centripetal.
B) nuclear.
C) gravitational.
D) electrical.

Answer 1

*D) electrical.

Question 2

In an electrically neutral atom the number of protons in the nucleus is equal to the number of
A) neutrons in the nucleus.
B) electrons that surround the nucleus.
C) Choices A and B are both correct.
D) Choices A and B are both incorrect.

Answer 2

*B) electrons that surround the nucleus.

Question 3

Strip electrons from an atom and the atom becomes a
A) positive ion.
B) molecule.
C) different element.
D) negative ion.

Answer 3

*A) positive ion.

Question 4

To say that electric charge is quantized is to say that the charge on an object
A) is sometimes positive.
B) may occur in an infinite variety of quantities.
C) is a whole-number multiple of the charge of one electron.
D) can be neither created nor destroyed.
E) will interact with neighboring electric charges.

Answer 4

*C) is a whole-number multiple of the charge of one electron.

Question 5

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

Answer 5

*A) close together.

Question 6

To say that an object is electrically polarized is to say
A) it is electrically charged.
B) its charges have been rearranged.
C) it is to some degree magnetic.
D) it is only partially conducting.
E) its internal electric field is zero.

Answer 6

*B) its charges have been rearranged.

Question 7

The net charge on a charged capacitor depends on
A) the distance between the capacitor plates.
B) the medium between the capacitor plates.
C) the area of the capacitor plates.
D) All of the above choices are correct.
E) None of the above choices are correct, the net charge is zero.

Answer 7

*E) None of the above choices are correct, the net charge is zero.

Question 8

Particle A has twice the charge of nearby particle B. Compared to the force on Particle A, the force on Particle B is
A) four times as much.
B) half as much.
C) twice as much.
D) the same.
E) None of the above choices are correct.

Answer 8

*D) the same.

Question 9

Every proton in the universe is surrounded by its own
A) gravitational field.
B) electric field and gravitational field.
C) electric field
D) None of the above choices are correct.

Answer 9

*B) electric field and gravitational field.

Question 10

If you comb your hair and the comb becomes positively charged, then your hair becomes
A) uncharged.
B) positively charged.
C) negatively charged.

Answer 10

*C) negatively charged.

Question 11

A conductor differs from an insulator in that a conductor
A) has faster moving molecules.
B) has more electrons than protons.
C) has more protons than electrons.
D) has more energy than an insulator.
E) none of these

Answer 11

*E) none of these

Question 12

Charge carriers in a metal are electrons rather than protons because electrons are
A) smaller.
B) negative.
C) loosely bound.
D) none of these.

Answer 12

*C) loosely bound.

Question 13

In the unlikely case of a lightning strike, it is worse to be inside a building framed with
A) aluminum.
B) iron.
C) wood.
D) steel.

Answer 13

*C) wood.

Question 14

The electric field inside an uncharged metal ball is zero. If the ball is negatively charged, the electric field inside the ball is then
A) greater than zero.
B) zero.
C) less than zero.

Answer 14

*B) zero.

Question 15

A positive charge and a negative charge held near each other are released. As they move, the force on each particle
A) stays the same.
B) increases.
C) decreases.

Answer 15

*B) increases.

Question 16

An ampere is a unit of electrical
A) resistance.
B) pressure.
C) current.
D) none of these

Answer 16

*C) current.

Question 17

In an ac circuit, the electric field
A) is everywhere the same.
B) changes magnitude and direction with time.
C) increases via the inverse square law.
D) is non-existent.

Answer 17

*B) changes magnitude and direction with time.

Question 18

The current through a 10-ohm resistor connected to a 120-V power supply is
A) 10 A.
B) 1 A.
C) 12 A.
D) 120 A.

Answer 18

*C) 12 A.

Question 19

The primary source of electrons in an ordinary electrical circuit is
A) the electrical circuit itself.
B) the back emf of motors.
C) a dry cell, wet cell or battery.
D) the power station generator.

Answer 19

*A) the electrical circuit itself.

Question 20

In a common dc circuit, electrons move at speeds of
A) a fraction of a centimeter per second.
B) the speed of a sound wave.
C) the speed of light.
D) none of these

Answer 20

*A) a fraction of a centimeter per second.

Question 21

An electrical diode is useful for
A) changing ac to dc.
B) storing electrical energy.
C) limiting current.
D) voltage modification.
E) boosting voltage.

Answer 21

*A) changing ac to dc.

Question 22

Alternating current is normally produced by a
A) battery.
B) generator.
C) both
D) neither of these

Answer 22

*B) generator.

Question 23

On some early automobiles both headlights went out when one bulb burned out. The headlights must have been connected in
A) series.
B) perpendicular.
C) haste.
D) parallel.

Answer 23

*A) series.

Question 24

A circuit breaker often serves the same purpose as a
A) battery
B) capacitor.
C) fuse.
D) All of the above choices are correct.

Answer 24

*C) fuse.

Question 25

In a simple circuit containing a bulb, energy is given to the moving charges by
A) the battery.
B) the wires.
C) the bulb.
D) none of these

Answer 25

*A) the battery.

Question 26

A capacitor is used to store
A) both charge and energy.
B) charge.
C) energy.
D) neither charge or energy.

Answer 26

*A) both charge and energy.

Question 27

Two lamps, one with a thick filament and one with a thin filament, are connected in series. The current is greater in the lamp with the
A) thick filament.
B) thin filament.
C) the same in each lamp

Answer 27

*C) the same in each lamp

Question 28

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

Answer 28

*D) moving electric charge

Question 29

If a steady magnetic field exerts a force on a moving charge, that force is directed
A) in the direction of the motion.
B) opposite the motion.
C) at right angles to the direction of the motion.

Answer 29

*C) at right angles to the direction of the motion.

Question 30

An iron rod becomes magnetic when
A) its electrons stop moving and point in the same direction.
B) the net spins of its electrons are in the same direction.
C) its atoms are aligned having plus charges on one side and negative charges on the other.
D) positive ions accumulate at one end and negative ions at the other end.
E) none of these

Answer 30

*B) the net spins of its electrons are in the same direction.

Question 31

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) north or south pole - no difference really.

Answer 31

*A) north pole.

Question 32

The field surrounding every moving electron is
A) always electric but never magnetic.
B) always magnetic but never electric
C) always both electric and magnetic.
D) sometimes magnetic and sometimes electric.
E) none of the above

Answer 32

*C) always both electric and magnetic.

Question 33

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

Answer 33

*C) attract.

Question 34

Magnet A has twice the magnetic field strength of Magnet B and at a certain distance pulls on magnet B with a force of 100 N. The amount of force that magnet A exerts on magnet B is
A) at or about 50 N.
B) exactly 100 N.
C) More information is needed.

Answer 34

*B) exactly 100 N.

Question 35

If a compass is moved from the northern hemisphere to the southern hemisphere, its magnetic needle will change direction
A) hardly at all.
B) by 180 degrees.
C) by 90 degrees.
D) none of these

Answer 35

*A) hardly at all.

Question 36

The force on an electron moving in a magnetic field will be the largest when its direction is
A) exactly opposite to the magnetic field direction.
B) at an angle other than 90 degrees to the magnetic field direction.
C) the same as the magnetic field direction.
D) perpendicular to the magnetic field direction.
E) none of these

Answer 36

*D) perpendicular to the magnetic field direction.

Question 37

Which force field can increase a moving electron’s speed?
A) only a magnetic field
B) either an electric or magnetic field
C) only an electric field
D) none of these

Answer 37

*C) only an electric field

Question 38

When there is a change in the magnetic field in a closed loop of wire
A) electromagnetic induction occurs.
B) a current is created in the loop of wire.
C) a voltage is induced in the wire.
D) all of these

Answer 38

*D) all of these

Question 39

Voltage can be induced in a wire by
A) moving a magnet near the wire.
B) changing the current in a nearby wire.
C) moving the wire near a magnet.
D) Choices A, B, and C are all true.
E) None of the above choices are true.

Answer 39

*D) Choices A, B, and C are all true.

Question 40

Superconducting electromagnets
A) may be possible in the distant future.
B) may be possible soon.
C) exist now.
D) are science fiction.

Answer 40

*C) exist now.

Question 41

If a magnet is pushed into a coil, voltage is induced across the coil. If the same magnet is pushed into a coil with twice the number of loops,
A) twice as much voltage is induced.
B) one half as much voltage is induced.
C) four times as much voltage is induced.
D) the same voltage is induced.
E) none of these

Answer 41

*A) twice as much voltage is induced.

Question 42

Thrust a magnet into a coil of wire and the coil
A) becomes an electromagnet.
B) has a current in it.
C) both of these
D) neither of these

Answer 42

*C) both of these

Question 43

A device that transforms electrical energy to mechanical energy is a
A) generator.
B) transformer.
C) magnet.
D) motor.

Answer 43

*D) motor.

Question 44

If the voltage produced by a generator alternates, it does so because
A) unlike a battery, it produces alternating current.
B) the current it produces alternates.
C) the changing magnetic field that produces it alternates.
D) alterations in the mechanical energy input.
E) in effect it is an ac motor in reverse.

Answer 44

*C) the changing magnetic field that produces it alternates.

Question 45

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

Answer 45

*A) change in magnetic field for operation.

Question 46

Power is transmitted at high voltages because the corresponding current in the wires is
A) low so that overheating of the wires is minimized.
B) also, high to deliver appreciable power to distant places.
C) Choices A and B are both true.
D) Choices A and B are both false.

Answer 46

*A) low so that overheating of the wires is minimized.

Question 47

A step-up transformer has a ratio of one to ten. Neglecting slight losses, if 100 W of power go into the primary coil, the power coming from the secondary coil is
A) 1 W.
B) 100 W.
C) 10 W.
D) 1000 W.
E) none of these

Answer 47

*B) 100 W.

Question 48

Metal detectors, like the ones used at airports, are activated by
A) electromagnetic induction.
B) magnetic fields.
C) alternating current.
D) electric fields.

Answer 48

*A) electromagnetic induction.

Question 49

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

Answer 49

*D) 55 V.

Question 50

If the primary of a transformer were connected to a dc power source, the transformer would have a voltage output
A) only while being connected or disconnected.
B) that is also dc.
C) the same.
D) at a higher efficiency than with an ac source.

Answer 50

*A) only while being connected or disconnected.