Phys chapter 22 test 5

31) Like kinds of magnetic poles repel while unlike kinds of magnetic poles

attract

8) An electron and a proton

attract each other

37) Thrust a magnet into a coil of wire and the coil

becomes an electromagnet has a current in it. *C) both

15) Which statement is correct?

charges flow in a clossed circuit

33) An electron is shot through a spot somewhere between the ends of a horseshoe magnet. The electron

direction is changed

17) Heat a copper wire and its electric resistance

increases

32) Magnetic domains normally occur in

iron

26) The source of all magnetism is

moving electric charge

4) To say that electric charge is conserved is to say that electric charge

*E) can be neither created nor destroyed.

21) When a 60-watt light bulb is connected to a 120-volt source the current in the light bulb is

0.5 a

50) Neon signs require about 12,000 volts to operate. If the circuit uses a 120-volt power source, the ratio of primary to secondary turns on the transformer should be

1:100

23) The power dissipated in a 4-ohm resistor carrying 3 A is

36 w

47) A certain transformer doubles input voltage. If the primary coil has 10 A of current, then the current in the secondary coil is

5 a

14) Electrons are made to flow in a wire when there is

a potential difference across its ends

36) When there is a change in the magnetic field in a closed loop of wire

electromagnetic induction occurs a current is created in the loop of wire. a voltage is induced in the wire *D) all of these

30) Compared to the huge force that attracts an iron tack to a strong magnet, the force that the tack exerts on the magnet is

equally huge

35) Superconducting electromagnets

exist now

10) To say that an object is electrically polarized is to say

its charges have been rearranged

29) The intensity of cosmic rays bombarding the Earth's surface is largest at the

poles

13) When the distance between two charges is halved, the electrical force between the charges

quadruples

12) After a capacitor is fully charged, the total number of electrons it contains

remains unchanged

6) A difference between gravitational and electric forces is that electrical forces

repel or attract

24) The ratio of the potential difference across a metallic conductor to the current in the conductor is known as

resistance

38) The magnetic field strength inside a current-carrying coil will be greater if the coil encloses a

rod of iron

7) A transistor is an example of a

semiconductor

43) Compared to the primary voltage, the secondary voltage may be

smaller, larger, or the same

22) Compared to the amount of electric current in the filament of a lamp, the amount of current in the connecting wire is

the same

40) A transformer transforms

voltage

A positive ion has more

*E) protons than electrons.

19) Alternating current is normally produced by a

generator

39) 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,

*C) twice as much voltage is induced.

5) The unit of electric charge, the coulomb, is the charge on

*E) a specific large number of electrons.

25) Moving electric charges will interact with

*A) an electric field or a magnetic field.

28) Magnetic field lines about a current-carrying wire

*A) circle the wire in closed loops.

3) To say that electric charge is quantized is to say that the charge on an object

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

45) Disconnect a small-voltage battery from a coil of many loops of wire and a large voltage is produced by

*A) the collapse in the magnetic field.

34) When a bar magnet is broken in two, each half is

*B) at most half as strong as the original magnet.

49) The principal advantage of ac power over dc power is that

*C) ac voltage can be transformed via conventional transformers.

16) Electrons move in an electrical circuit

*C) by interacting with an established electric field.

42) Transformers use ac so there will be the required

*C) change in magnetic field for operation.

27) An iron rod becomes magnetic when

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

46) Rapid change of a magnetic field induces

electric field

41) An electric motor is very similar to

electric generator

Which force binds atoms together to form molecules?

electrical

9) Two protons attract each other gravitationally and repel each other electrically. By far the greater force is

electrical repulsion

48) Metal detectors, like the ones used at airports, are activated by

electromagnetic induction

44) The output power of an ideal transformer is

equal the input power

18) A wire carrying a current is normally charged

not at all

11) When a car is struck by lightning, the resulting electric field inside the car is

zero

20) The number of electrons delivered daily to an average American home by an average power utility in the mid-1980s was

zero