ELEC-256 [1-6] Flashcards
1
Q
A
Basic Circuit - Pictorial representation
2
Q
A
Basic Circuit - Schematic Representation
3
Q
One to four valance electrons
A
Conductors
4
Q
Semiconductors
A
Five Valance Electrons
5
Q
More than Five Valance Electrons
A
Insulators
6
Q
The long bar denotes the _______ and the short bar ______
A
- Positive Terminal
- Negative Terminal
7
Q
A
Symbol for a cell
8
Q
A
Symbol for a battery
9
Q
A
A 1.5 volt battery
10
Q
When the amount of charge that passes a point in one second is one coulomb, the current is
A
One Ampere
11
Q
A
Voltmeter
12
Q
A
Ammeter
13
Q
A
Cells in series
14
Q
A
Cells in Parallel
15
Q
Describe
A
Measuring Voltage
- To measure voltage place the voltmeter leads across the component whose voltage you wish to determine.
16
Q
A
Measuring current
- To measure current, insert the ammeter into the circuit so that the current you wish to measure passes trough the instrument
17
Q
A
Open circuit
18
Q
A
Closed circuit
19
Q
A
Using a fuse to protect a circuit
20
Q
A
Basic Resistive Circuit
21
Q
Resistance
A
Is an opposition to current flow. It can be thought of as friction in the circuit. Resistance is measure in Ohms
22
Q
Ohm’s law
A
23
Q
For a fixed resistance Ohm found that doubling the voltage____
A
Doubled the current
24
Q
For a fixed voltage Ohm found that the opposition to current was
A
directly proportional to the lenght of the wire and inversely proportional to its cross-sectional area
25
Ohms was able to show that current is inversely proportional to
resistance e.g when he double the resistance he found that the current decreased to half of its former value
26
The resistance of a material is dependent on:
1. Type of material
2. Lenght of the conductor
3. Cross-Sectional area
4. Temperature
27
The resistance of a metallic conductor is inversely proportional to the ...
Cross sectional area of the conductor
28
1. p=resistivity, in ohm meters
2. l=lenght in meters
3. A=across-sectional area in square meters
29
If the diameter of a wire is doubled, its resistance will be...
One-fourth as great
30
31
Any material for which resistance increases as temperature increases is said to have a...
positive temperature coefficient
32
33
Types of resistors
1. Fixed resistors (constant resistance values)
2. Variable resistors (potentiometers and rheostats)
34
35
36
Defined as the rate of doing work
Power
37
Defined as work per unit charge
voltage
38
The rate of transfer of charge
current
39
Formulas for Power
40
41
Defined as the ratio of power output Pout to power input Pin usually expressed in percent and the noted by the greek letter Π (eta)
Efficiency of a device or system
42
43
is the combination of any number of sources and loads connected in any manner that allows charge to flow
An Electric Circuit
44
All electric circuits obtain their energy either from ...
a direct current (dc) source or from an alternating current (ac) source
45
What two conditions determine whether two elements are connected in series?
Two elements are said to be in series if they are connected at a single point and if there are no other current-carrying connections at this point.
46
The summation of voltage rises and voltage drops around a closed loop is equal to zero
Kirchhoff's voltage law
47
Is defined as any path that originates at a point, travels around a circuit, and returns to the original point without retracing any segments
A closed loop
48
49
50
If a circuit has more than one voltage source in series then the voltage sources may effectively be replaced by...
A single source having a value that is the sum or difference of the individual sources
51
Voltage Polarities
When voltage sources do not result in voltage rises in the same direction
52
A typical lead-acid automobile battery consists of six cells connected in series. If the voltage between the battery terminals is measured to be 13.6 V, what is the average voltage of each cell within the battery?
53
Interchanging series components
The order of series components may be changed without affecting the operation of the circuit.
54
The voltage dropped across any series resistor is proportional to the magnitude of the resistor. The total voltage dropped across all resistors must equal the applied voltage source(s) by KVL.
The Voltage Divider Rule
55
If the output terminals are shorted together, the current in the circuit will be a maximum and the terminal voltage will be equal to approximately zero.
In such a situation, the voltage dropped across the internal resistance will be equal to the voltage of the ideal source.
56
Terminal Voltage
The voltage that appears between the positive and negative terminals
57
Simplify the circuit shown below into a single source in series with the four resistors. Determine the direction and magnitude of the current in the resulting circuit.
58
An "arbitrary electrical point of reference" or "common point" in a circuit
Circuit Ground
59
If an ammeter having an internal resistance of 250 Ω is used to measure the current in the circuits, determine the current through the ammeter and calculate the loading effect for each circuit
60
Kirchhoff's Current Law (KCL)
The summation of currents entering a node is equal to the summation of currents leaving the node.
61
Verify that Kirchhoff's current law applies
3 mA + 6 mA + 1mA = 2 mA + 4 mA + 4 mA
62
Determine the unknown currents
63
An important effect of combining parallel resistors is that the resultant resistance will always be ...
smaller than the smallest resistor in the combination.
64
Solve for the total conductance and total equivalent resistance
65
Determine the conductance and resistance of the network
