問題一覧
1
A generator converts ……… energy into electrical energy.
mechanical
2
Electrical current in which there is no net motion of the charge carriers is
alternating current
3
In alternating current, the charge carriers move
repeatedly in one direction then in the opposite direction
4
Electrical appliances have labels that state the power used by the appliances. What does the power rating listed on the label represent?
the amount of energy converted each second into other forms of energy
5
Electrical power is the rate at which charge carriers
do work
6
The phenomenon called l2 R loss is also known as
joule heating
7
Which statement is correct regarding electric power?
Electric power equals the current times potential difference
8
A certain circuit connected to a 1.5 v battery dissipates 2.0 W of power. If a second battery is added to the circuit, resulting in a potential difference of 3.0 V , what power will be dissipated? Assume that the resistance of the circuit does not change.
4.0 W
9
A load in a circuit
dissipates energy
10
The symbols in the diagram above indicate
one battery, three lamps, and one open switch.
11
The part of a circuit that converts electrical energy to other forms of energy is
the load
12
A short circuit is
both a and c
13
Which of the schematics shown above conducts electricity through the lamp?
A and C
14
Three lamps are arranged as shown above. Which single lamp must burn out to cause all of the lamps to go out .
lamp 2
15
Which is correct regarding the terminal voltage of a battery?
Terminal voltage is always less than the emf of the battery
16
A battery is used to supply power to a portable MP3 player. If the terminal voltage across the battery is 4.5 V, what is the potential difference across the MP3 player?
4.5 V
17
Several resistors are wired in a circuit so that there is a single path for the flow of electric current. What type of circuit is this?
series circuit
18
Five resistors are wired in a series circuit. How does the equivalent resistance of the circuit compare to the resistances of the individual resistors?
The equivalent resistance is greater than any single resistance.
19
Several resistors are wired in series. What is true about this circuit?
The total circuit current is the same as the current through any one of the resistors
20
Two resistors and a battery are wired in a series circuit. One resistor has twice the resistance of the other resistor. What is true about the voltage across the two resistors?
One-third of the battery voltage is across the lower value resistor
21
The current through one resistor in a parallel resistor circuit is always
less than the total current in the circuit
22
What distinguishes a parallel circuit from a series circuit?
A parallel circuit always has more than one current path
23
Four resistors having equal values are wired as a parallel circuit. How does the equivalent resistance of the circuit compare to the resistance of a single resistor?
The equivalent resistance is one-fourth the resistance value ofa single resistor.
24
Six resistors are wired in a parallel circuit. What is the voltage across each resistor in the circuit if the first resistor is connected to a 24 V battery?
24 V
25
You want to determine the current in a complex circuit. Which piece ofinformation will be least helpful in making your determination?
the number of devices in the circuit
26
You have three 100 resistors available. How would you connect these three resistors to produce a 150 equivalent resistance? You must use all of the resistors.
Connect one resistor in series with two resistors in parallel.
27
A circuit is constructed as follows: four resistors in parallel connected in series with three resistors in parallel connected in series with two resistors in parallel. All of the resistors have the same value. How does the equivalent resistance of this circuit compare to the resistance of asingle resistor?
The equivalent resistance is greater than a single resistor.
28
Because household devices are connected in parallel in a circuit, ___________ as new devices are connected
the potential difference remains the same
29
In any complex resistance circuit, the current through any resistor in the circuit is always
less than or equal to the total circuit current.
30
In the circuit shown above, which resistors, if any, have equal voltages across them?
R a and R d
31
A circuit breaker is designed to limit the amount of __________ in a circuit
current
32
Which of the following devices is always connected in series with a household circuit?
fuse
33
Any device that increases the potential energy of charges circulating in a circuit is called
emf
34
The emf is the energy per unit charge supplied by a source of electrical current
true
35
Batteries and generators are examples of emf sources
true
36
For conventional current, the terminal voltage is more than the emf
false
37
The potential difference across the battery’s terminals , the terminal voltage , is actually slightly less than the emf
true
38
Potential difference across a battery should be taught of as the potential difference
true
39
The potential difference across a load ——— the terminal voltage
equals
40
A set of electrical components connected such that they provide one or more complete paths for the movement of charges
electric circuit
41
Any element or group of elements in a circuit that dissipates energy is called a
load
42
There is a closed -loop path for electrons to follow
a closed circuit
43
There is no charge flow and therefore no
open circuit
44
is transferred at high potential difference to minimize energy loss
Electric energy
45
The rate at which work is done
electric power
46
Electric power
P= I <| v
47
Electric power:::
p = I <| v = I (I R) = I 2 R p = I <| v = (<| V / R ) <| V = (<| V )2 / R
48
A representation of a circuit that uses lines to represent wires and different symbols to represent components
schematic diagram
49
Can be hazardous
short circuit
50
Short closed circuit that does not cointain a load
true
51
Batteries and generators supply energy to charge carriers
true
52
Current cannot be direct or alternating
false
53
They are two different kinds of current direct current and alternating current
true
54
Charges move in only one direction with negative charges
direct current
55
Direct current however that the electrons actually move in the opposite direction
true
56
Potential difference across a load equals the terminal voltage
true
57
Transform non electrical into electrical energy is a source of
emf