Unit 31
What is a amperes (amps)
The rate of electrical currents flow
What is an alternating current?
a current of electrons that changes direction of flow
What is the maximum number of electrons in each energy level in the first , second, third and fourth?
1. 2 2. 8 3. 18 4. 32
Difference between DC generator and Ac generator?
A magnetic field induces current to flow in the armature windings located in the rotor for DC generators. AC armature windings are locates in the stator.
What is a semiconductor?
A material that conducts electricity better than an insulator but not as well as a conductor
What series stays the same in a circuit?
Amperage
What is a short circuit?
An electrical circuit that contains a source and path without a load.
How does electrical flow work?
An electron moves from one atom to another and causes an electron to leave that atom.
Static charges can only be neutral. True or False?
False, can be neutral, positively, or negatively charged
Doping can only produce positive charge in the semiconductor material. True or False
False, can produce negative or positive, depending on the chemical used
AC is available in single phase. True or False?
False, single phase and three phase
How can electricity be classified?
Static or dynamic
What are atoms made of?
protons, neutrons, electrons
What is electricity?
the flow of electrons
What are P-type (positive) semiconductors doped with?
Boron and gallium m.
What is direct current (DC)?
A continuous flow of electrons in one direction.
What semiconductor devices are made when joining N-type and P-type materials?
Diodes, transistors and rectifiers
In an AC generator, what causes a change in direction of current flow?
Each revolution of the rotor
Define free electron
Electrons that have escaped their atomic bonds.
How are electrons arranged?
Energy levels
What is resistance?
Opposition to the flow of electricity
What does P. I. E. R stand for?
P= W= power I= amp= A= current= intensity E= volts= V= Potential= Electromoto force R= ohms= resistance
What are N-type (negative) semiconductors doped with?
Phosphorous and arsenic
If an object loses electrons, what is the charge?
Positive
What's the charge for protons?
Positively
What is ohm'w law?
Relationship between the voltage, current, and resistance in an electrical circuit. E=IR
What is static electricity?
Result of a standing charge.
When do the resistance increase on conductors?
Rise in temperature
What mathematical formula is used to calculate the effective voltage?
Root mean square
What are some insulators?
1. Ceramic 2. Rubber 3. Plastics 4. Thermoplastics
What is DC used for?
1. Cordless tools (primarily) 2. Control systems 3. Electronic air cleaners 4. Operating electronic circuits
What are the common measurements terms used for electrical circuit?
1. Current 2. Voltage 3. Wattage 4. Resistance
What applications can the rotor reach high speeds of 3,600 rpm?
1. Electrical power generating plants 2. Steam turbines 3. Gas turbine
What are some good metal conductors?
1. Gold 2. Silver 3. Copper 4. Aluminum
What are other forms of energy that can be used to generate electricity?
1. Heat 2. Light 3. Chemical (common) 4. Mechanical 5. Magnetic (common)
What are some materials used for semiconductors?
1. Silicon (most common) 2. Carbon 3. Germanium
What makes a good conductor?
Atoms that have just a few electrons on their outer energy level.
What happens when electrons are farther away from the nucleus and not as tightly bonded?
Attraction is weaker
How is the energy level to the nucleus with fewer electrons?
Closest to the Nucleus
What is wattage?
Indicates power
What is a not a good conductor?
Insulators
How is the energy level to the nucleus when there is more electrons?
Is farthest away from the nucleus
What is dynamic electricity?
Is in motion created by flowing electrons
What makes a good electrical conductor?
Materials with a large number of free electrons.
What is coulomb?
Measure of electrical charge
What is voltage?
Measurement of potential
If the electrons are increased in an object, what is the charge?
Negative
What's the charge for electrons?
Negative
If the number of electrons and protons are equaled, what is the charge?
Neutral
What's the charge for neutrons?
No charge
What's in the center of a atom?
Nucleus composed of protons and neutrons.
What is phase?
Number of waveforms occurring at the same time.
What is doping?
The addition of trace amounts is another chemical into the the crystalline structure.
What is watt?
The measure of the rate at which electrical work is done.
Describe the basic structure of the atom.
The smallest piece of an element that can exist and still retain the same chemical properties is the atom.
Atoms that have just a few electrons on their outer energy level make a good conductor. True or False
True
The ability to make current flow is called electromotive force or potential. True or false?
True
The revolution in electronic circuits is based on the discovery and advancement of semiconductors. True or False
True
The voltage level of AC current can be more easily changed or transformed than DC current. True or False?
True
Usually the number of electrons and protons are equal. True of False
True
How do batteries generate electricity?
Turning chemical energy into electrical energy
How do generators create electricity?
Uses magnetic and mechanical energy
What is an electrostatic precipitator?
Uses static electricity to filter the air.
What are the two factors for the ability of electricity to do work?
Voltage and current