Electrical Theory Dc

Front 1

An atom that has lost or gained one or more electrons is said to have an ____

Back 1

ion charge

Front 2

______ is the term used to describe how large the electrostatic force is between two charged objects. If a charged body is placed between two objects with a potential difference, the charged body will try to move in one direction, depending upon the polarity of the object. If an electron is placed between a negatively charged body and a positively charged body, the action due to the potential difference is to push the electron toward the positively charged object.

Back 2

Potential difference

Front 3

The sum of the potential differences of all charged particles in the electrostatic field is referred to as _____

Due to the force of its electrostatic field, these electrical charges have the ability to do work by moving another charged particle by attraction and/or repulsion. This ability to do work is called "potential"; therefore, if one charge is different from another, there is a potential difference between them

Back 3

electromotive force (EMF)

Front 4

potential difference is also called ____

Back 4

"voltage."

Front 5

_____ are materials with electrons that are loosely bound to their atoms, or materials that permit free motion of a large number of electrons.

Back 5

Conductors

Front 6

Elements, in which the valence shell is almost empty, that is, those, which have only one or two electrons, tend to give up these electrons very easily. Substances, which have a large number of, free electrons

Back 6

Conductors

Front 7

______, or nonconductors, are materials with electrons that are tightly bound to their atoms and require large amounts of energy to free them from the influence of the nucleus

Back 7

Insulators

Front 8

The Closer that a valence shell is to having its full complement of eight means that the more stable the element is. An element whose valence shell is short of being completely filled will try to attract and hold free electrons. Substances, which have very few free electrons, are called ______

Back 8

insulators

Front 9

____ are made of materials that conduct electricity, but offer opposition to current flow

Back 9

Resistors

Front 10

Current flow continuously in the same direction

Back 10

Direct Current

Front 11

Current flow periodically reverses direction

Back 11

Alternating Current

Front 12

It is the property of an electric circuit that opposes the movement of electrons and dissipates power. _____ is measured in ohms and is represented by the symbol (R) in equations. One ohm is defined as that amount of resistance that will limit the current in a conductor to one ampere when the potential difference (voltage) applied to the conductor is one volt. The shorthand notation for ohm is the Greek letter omega

Back 12

Resistance

Front 13

_________ is defined as the measure of the resistance a material imposes on current flow. The resistance of a given length of conductor depends upon the resistivity of that material, the length of the conductor, and the cross-sectional area of the conductor

Back 13

Resistivity

Front 14

Electricity is generally used to do some sort of work, such as turning a motor or generating heat. Specifically, _____ is the rate at which work is done, or the rate at which heat is generated. The unit commonly used to specify electric _____ is the watt.

is also described as the current (I) in a circuit times the voltage (E) across the circuit.

Back 14

power

Front 15

______ is defined as the ability of a coil to store energy, induce a voltage in itself, and oppose changes in current flowing through it. The symbol used to indicate inductance is a capital L.

Back 15

Inductance

Front 16

______ is defined as the ability to store an electric charge and is symbolized by the capital letter C. Capacitance (C), measured in farads

Back 16

Capacitance

Front 17

Chemicals can be combined with certain metals to cause a chemical reaction that will transfer electrons to produce electrical energy.

A chemical reaction produces and maintains opposite charges on two dissimilar metals that serve as the positive and negative terminals. The metals are in contact with an electrolyte solution. Connecting together more than one of these cells will produce a battery.

Back 17

Electrochemistry

Front 18

Atoms with the proper number of electrons in orbit around them are in a neutral state, or have a "zero charge." Bodies of matter consisting of these atoms will neither attract nor repel other matter that is in its vicinity. If electrons are removed from the atoms in this body of matter, as happens due to friction when one rubs a glass rod with a silk cloth, it will become electrically positive

If this body of matter (e.g., glass rod) comes near, but not in contact with, another body having a normal charge, an electric force is exerted between them because of their unequal charges.

Back 18

Static Electricity

Front 19

is used to produce a voltage by rotating coils of wire through a stationary magnetic field, or by rotating a magnetic field through stationary coils of wire. This is one of the most useful and widely employed applications of producing vast quantities of electric power

Back 19

Magnetic Induction

Front 20

By applying pressure to certain crystals (such as quartz or Rochelle salts) or certain ceramics (like barium titanate), electrons can be driven out of orbit in the direction of the force. Electrons leave one side of the material and accumulate on the other side, building up positive and negative charges on opposite sides.

When the pressure is released, the electrons return to their orbits. Some materials will react to bending pressure, while others will respond to twisting pressure.

If external wires are connected while pressure and voltage is present, electrons will flow and current will be produced. If the pressure is held constant, the current will flow until the potential difference is equalized.

Back 20

Piezoelectric Effect

Front 21

_____ refers to the ability of a material to concentrate magnetic lines of flux.

Materials that can be easily magnetized are considered to have a high ___

Back 21

Permeability (µ)

Front 22

_____ is the strength of a magnetic field in a coil of wire.

Back 22

Magnetomotive force (MMF)

Front 23

Opposition to the production of flux in a material is called _____, which corresponds to resistance.

Back 23

reluctance

Front 24

Reluctance is inversely proportional to _____

Back 24

permeability (µ).

Front 25

determines the polarity of the induced voltage. Induced voltage has a polarity that will oppose the change causing the induction.

When current flows due to the induced voltage, a magnetic field is set up around that conductor so that the conductor’s magnetic field reacts with the external magnetic field.
This produces the induced voltage to oppose the change in the external magnetic field

Back 25

Lenz’s Law

Front 26

The purpose of a rectifier circuit is to ___

Back 26

convert AC power to DC.

Front 27

The output of this circuit then becomes a pulsating DC, with all of the waves of the input AC being transferred.

Back 27

Full wave bridge rectifier

Front 28

A ____ is an uninterrupted, or unbroken, path for current from the source (EMF), through the load, and back to the source.

Back 28

closed circuit

Front 29

An _____, or incomplete circuit, exists if a break in the circuit occurs; this prevents a complete path for current flow

Back 29

open circuit

Front 30

A _____ is a circuit, which offers very little resistance to current flow and can cause dangerously high current flow through a circuit

Back 30

short circuit

Front 31

A ___ is a circuit where there is only one path for current flow. In a series circuit, the current will be the same throughout the circuit. This means that the current flow through R1 is the same as the current flow through R2 and R3.

Back 31

series circuit

Front 32

In a parallel circuit, the total resistance of the resistors in parallel is referred to as _____ In all cases, this will be less than any of the individual parallel circuit resistors.

Back 32

equivalent resistance.

Front 33

______ supplies all DC loads and keeps battery fully charged at all times

Back 33

Charger

Front 34

_____ increases capacity because the chemical react better at higher temperature

Back 34

Raising temperature

Front 35

______ decreases capacity due to reverse of above.Rated based on 77 degrees F (25C)

Back 35

Lowering temperature

Front 36

State OHMS law

Back 36

E = IR

I = current (AMPS)
E = Voltage (V)
R = Resistance

Front 37

_____ can be described as the current (I) in a circuit squared times the resistance (R) of the circuit.

Back 37

POWER
P= (I^2) R

PIIR

Front 38

series resistance =

Back 38

R1 + R2 +R3

Front 39

What is the purpose of a battery?

Back 39

To store chemical energy and convert this chemical energy into electrical energy when the need arises

Front 40

A discharged battery will have ____ , indicating that much of the sulfuric acid has reacted with the plates. Leaving behing mostly water in the electrolyte solution

Back 40

a LOW Specific Gravity.

Front 41

_____ is slightly higher than nominal battery voltage

Back 41

Float Charging Voltage

Front 42

_____ is higher than both float and nominal

Back 42

Equalizing Charging Voltage

Front 43

More _____ = More Torque

Back 43

Armature Current

Front 44

What does a rectifier do?

Back 44

AC to DC

Front 45

What is the effect of hooking up batteries in Series

Back 45

same current , more voltage

Front 46

Causes electrons to flow

Back 46

Volage (water tower)

Front 47

1 to 3 electrons in the outer shell

Back 47

Conductor

Front 48

What causes electromotive force?

Back 48

potential difference

Front 49

Armature current is ____ to torque

Back 49

directly proportional

Front 50

describes flow from - to +

Back 50

electron flow

Front 51

describes flow from + to -

Back 51

whole flow (conventional flow)