# Electrical Sciences DC Theory

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1. Two or more chemical cells connected in a series.
Batteries
2. Graphic representation used to show the relationship between component group or stages in a circuit.
Block diagram
3. Direction of electron flow is from a point of negative potential to a point of positive potential.
Conventional and electron flow
4. To find the individual branch currents in a parallel circuit when only resistance and total current are known, the resistance in each circuit can be used to divide the total current into fractional currents in each branch.
Current division
5. Sum of the currents flowing through each branch of a parallel circuit is equal to the total current flow in the circuit.
Current in parallel
6. An armature coil cuts across the magnetic field to produce a voltage output.
DC generator
7. When the positive terminal of a voltage source is connected to a diode’s anode, and the negative terminal is connected to the cathode.
Forward bias
8. A circuit that rectifies the entire cycle of the AC sine wave.
Full-wave rectifier
9. When a single diode is used in a rectifier circuit, current will flow through the circuit only during one half of the input voltage cycle.
Half-wave rectifier
10. Law 1: The sum of the voltage drops around a closed loop is equal to the sum of the voltage sources of that loop (Kirchhoff’s Voltage Law).

Law 2: The current arriving at any junction point in a circuit is equal to the current leaving that junction (Kirchhof’'s Current Law).
Kirchhoff’s laws
11. Graphic representation showing the components of a circuit by means of single lines and the appropriate graphic symbols.
One-line diagram
12. If one of the paths for current to flow is opened, current will continue to follow as long a some or more of the remaining paths provides a complete path.
Open circuit (parallel)
13. If the path for current is broken no current flows.
Open circuit (series)
14. Circuits that have two or more components connected across the same voltage source.
Parallel circuit
15. Converts AC power to DC power.
Rectifiers
16. Total resistance in a parallel circuit can be found by applying Ohm’s Law. Divide the voltage across the parallel resistance by the total line current.
Resistance in parallel
17. Total resistance in a series circuit is equal to the sum of all the parts of that circuit.
Resistance in series
18. The measure of the resistance a material imposes on current flow.
Resistivity
19. When the diode’s anode is connected to the negative side of the source, and the cathode is connected to the positive side of the source.
Reverse bias
20. The standard means by which we communicate information in electrical and electronics circuits.
Schematic diagram
21. A circuit where there is only one path for current flow.
Series circuit
22. A sudden and very large increase in circuit current associated with a zero or very low resistance current path.
Short circuit (parallel)
23. If there is no resistance in a circuit or if resistance suddenly becomes or approaches zero, a very large current will flow. Condition of very low resistance and high current flow.
Short circuit (series)
24. Is defined as the amount of change of the resistance of a material for a given change in temperature.
Temperature coefficient (α)
25. Consists of two different types of metal joined at a junction and is used to convert heat energy into a voltage output.
Thermocouples
26. Used when it is necessary to obtain different values of voltage from a single energy source.
Voltage divider
27. A very simple way to show wiring connections in an easy to follow manner.
Wiring diagram
28. LIST the four ways to produce a DC voltage.
• Batteries
• DC Generator
• Thermocouples
• Rectifiers
29. STATE the purpose of a rectifier.
The purpose of a rectifier circuit is to convert AC power to DC power
30. DESCRIBE the outputs of the following circuits:
a. Half-wave rectifier
b. Full-wave bridge rectifier
When a single diode is used in a rectifier circuit, current will flow through the circuit only during one-half of the input voltage cycle

A full-wave rectifier circuit is a circuit that rectifies the entire cycle of the AC sine-wave
31. DESCRIBE what is meant by the term “voltage divider”.
A voltage divider, or network, is used when it is necessary to obtain different values of voltage from a single energy source
32. DESCRIBE the voltage and current effects of an open in a series DC circuit
Circuits can be opened deliberately, such as by the use of a switch, or they may be opened by a defect, such as a broken wire or a burned-out resistor.

Since no current flows in an open series circuit, there are no voltage drops across the loads. The loads consume no power, and total power consumed by the circuit is zero.
33. DESCRIBE the voltage and current effects in a shorted DC circuit.
If there is no resistance in a circuit, or if the resistance suddenly becomes or approaches zero, a very large current will flow.
34. STATE Kirchhoff’s Voltage Law
The sum of the voltage drops around a closed loop is equal to the sum of the voltage sources of that loop
35. STATE Kirchhoff’s Current Law.
The current arriving at any junction point in a circuit is equal to the current leaving that junction
36. Block Diagram
37. One Line
38. Wiring Diagram
39. Schematic Diagram
40. The measure of the resistance a material imposes on current flow.
Resistivity
41. The amount of change of the resistance of a material for a given change in temperature
Temperature coefficient of resistance
42. An uninterrupted, or unbroken, path for current from the source (EMF), through the load, and back to the source.
Closed Circuit
43. Incomplete circuit, exists if a break in the circuit occurs; this prevents a complete path for current flow.
Open Circuit
44. A circuit that offers very little resistance to current flow and can cause dangerously high current flow through a circuit
Short Circuit
 Author: ereim ID: 29541 Card Set: Electrical Sciences DC Theory Updated: 2010-08-11 14:46:10 Tags: DC Theory Folders: Description: DC Theory Show Answers: