Exam #3 UPS

what are things that can increase resistance?

1) size (thinner wire) 2) length (longer wire) 3) material (rubber) 4) temperature (higher temperature)

Magnet A has 2x 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 ___________

100 N

34) An electric generator of itself A) cannot produce energy, but convert energy of other forms to electric energy. B) can produce enough energy to light cities. C) neither

A) cannot produce energy, but convert energy of other forms to electric energy

23) Magnetic field lines about a current-carrying wire A) circle the wire in closed loops. B) extend radially from the wire. C) both D) neither

A) circle the wire in closed loops

24) Earthʹs magnetic field affects cosmic rays by A) deflecting them. B) destroying them. C) absorbing them. D) slowing their speeds.

A) deflecting them

5) The number of protons in the nucleus of an electrically neutral atom is equal to the number of A) electrons that surround the nucleus. B) neutrons in the nucleus. C) both D) neither

A) electrons that surround the nucleus

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

A) has a single direction

15) Stretch a copper wire so that it is thinner and the resistance between its ends A) increases. B) remains unchanged. C) decreases.

A) increases

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

A) its charges have been rearranged

10) Electric potential Energy is measured in units of A) joules. B) volts. C) amperes. D) watts.

A) joules

18) When two lamps are connected in parallel to a battery, the electric resistance that the battery senses is A) less than the resistance of either lamp. B) more than the resistance of either lamp. C) none of the above

A) less than the resistance of either lamp

19) Compared to a single lamp connected to a battery, two lamps connected in parallel to the same battery will draw A) more current. B) the same current. C) less current.

A) more current

20) The headlights, radio, and defroster fan in an automobile are connected in A) parallel. B) order of energy efficiency. C) series.

A) parallel

1) The nucleus of an atom is charged A) positively. B) negatively. C) both C) both

A) positively

2) When you remove electrons from a metal cup, the cup becomes A) positively charged. B) ionized. C) negatively charged.

A) positively charged

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

A) the magnetic field that produces it alternates

22) An iron rod becomes magnetic when A) the net spins of its electrons are in the same direction. B) positive ions accumulate at one end and negative ions at the other end. C) its atoms are aligned with positive charges on one side and negative charges on the other side. D) electron motion stops. E) none of the above

A) the net spins of its electrons are in the same direction

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

B) electric current

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

B) electromagnetic induction

14) The electric current in a copper wire is normally composed of A) ions. B) electrons. C) protons. D) all or any of the above

B) electrons

35) A transformer actually transforms A) generators into motors. B) energy from one value of voltage to another. C) non-safe forms of energy to safe forms of energy. D) magnetic field lines. E) all of the above

B) energy from one value of voltage to another

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

B) generator

27) Compared to a motor, a generator is A) of an entirely different design. B) it's opposite. C) one and the same.

B) it's opposite

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

B) repel each other

16) When a person experiences an electric shock, the origin of the electrons comprising the shock is A) a power plant. B) the personʹs own body. C) the ground. D) likely a faulty lamp. E) the electric field in the air.

B) the personʹs own body

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

B) the roles of input and output

17) The electric resistance of a superconductor is A) usually lower than that of ordinary resistors. B) zero. C) infinite.

B) zero

31) When a magnet is thrust into a coil of wire, a greater voltage is induced A) with a greater number of loops in the coil. B) with faster thrusting motion. C) both D) neither

C) both

13) Which statement is correct? A) voltage flows through a circuit B) resistance is established across a circuit C) charge flows through a circuit D) current causes voltage

C) charge flows through a circuit

9) A balloon will stick to a wooden wall if the balloon is charged A) positively. B) negatively. C) either D) neither

C) either

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

C) isolated

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

C) motor

4) One main difference between gravitational and electric forces is that electric forces A) are weaker. B) act over shorter distances. C) repel or attract. D) attract. E) obey the inverse-square law.

C) repel or attract

12) The reason that Lillianʹs hair stands out when her hand is on a charged Van de Graaff generator is A) a high voltage is communicated to strands of hair. B) electrons and protons are deposited on her hair. C) strands of hair become charged and repel one another. D) strands of hair find themselves in an electric field.

C) strands of hair become charged and repel one another

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

D) all of the above

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

D) all of the above

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

D) is a whole-number multiple of the charge of one electron

what causes electric charge flowing in an electric circuit?

The cause is the difference in pressure.

What does "electric charge is conserved" mean?

The meaning is that in any charging process there are no electrons created or destroyed, they are just transferred from one material to another.

when a bar magnet is broken in half, each half becomes _______________________

a new magnet with N and S poles.

a balloon will stick to the wall when it is a) negatively charged b) positively charged c) either

c)either

A galvanometer measure _________

current

changing the magnetic field intensity in a closed loop of wires induces ________ and ________

current; voltage

the rule for interaction of magnetic poles is similar to the rule for ________

electric charges

another term for voltage is _________________

electric pressure

An object is positively/negatively charged when it looses/gains ________

electrons

when a person experiences an electric shock the origin of the electrons comprising the shock is ____________________

from your own body

alternating current is normally produced by a ________

generator

One main difference between gravitational and electric force is ____________________

gravity only attracts while electricity can attract and repel.

A bar magnet that holds a chain of nails illustrates magnetic __________

induction

To say that an object is electrically polarized means ________________________

it has a distortion of charge or the rearranging of charges.

electric potential energy is measured in units of ___________

joules

a rubber rod rubbed with fur becomes _________ charged

negatively

the electron is __________ charged

negatively

the neutron is _____________ charged

nuetrally

the unit of electrical resistance is _________

ohm's

The nucleus is _________ charged

positively

The proton is ___________ charged

positively

When you remove electrons from a metal cup, the metal cup becomes __________ charged

positively

a pair of positively charged straws will ______ each other

repel

the flow of charge in a circuit depends on ___________________

the difference of potential

the difference between AC and DC is _____________

the direction they flow.

The reason that hair of somebody stands out when her hand is on a charged Van de Graaff generator is ______________

the hair becomes charged and the strands repel each other

the difference between magnetic poles and electric charges is _______________________

the magnetic poles cannot be isolated like electric charges can

The source of all magnetism is ___________________________________________

the movement of electrons when they spin on their axis around the nucleus.

The objects become charged because ______________________________________________________

the number of positive and negative charges are not balanced. It will either have more electrons or more protons.

A charged balloon illustrates that something can have a great amount of ________ and a small amount of ________

voltage; energy

electric potential is measured in units of _____________

volts

the number of electrons delivered daily by power utilities to an average American home in a typical year in this century is ________

zero