Test Review Flashcards
Name two safety rules
Think- think of all the rules concerning safety.
Work with one hand when possible- worst electric shock occurs when the current path is from hand to hand.
How many amps does it take to cause death?
0.1-0.2 amps
Name the types of PPE.
- Head protection
- Eye protection
- Hearing protection
- Fire-retardant clothing
- Gloves
- Safety harness
What is the rule for setting a ladder?
Angle of a ladder is 76 degrees and rise over run 4:1
What are the types of electrical sources?
A/C- bidirectional
D/C- unidirectional
What is an Atom and what does it consist of?
An atom is the smallest unit of matter. It has in its nucleus a nuetron-nuetral, and a proton-positive. The outside of the nucleus has electrons-negative.
What is the outer shell of an atom and its properties?
The outer shell is the valence shell and it contains the valence electrons with no more than 8 in it.
What is a conductor?
Is made from a material that permits electrical flow. It has 1-3 electrons in it so it gives them up easily.
What is electrical flow?
It is the flow of electrons thru a conductor.
What is an insulator?
An insulator is a material that resist the flow of electrons. It has 7 or 8 electrons in its valence shell.
What is a semiconductor?
A semiconductor is a material that is neither a good conductor or insulator. It has four valence electrons.
Name the methods of producing electricity
- Magnetism
- Chemical action
- Pressure
- Heat
- Friction
- Light
What is a coulomb?
A coulomb is a quanity of measure of electrons. It contains 6.25x10 to the 18 electrons.
What is a volt?
A volt is the potential difference or electromotive force. (Emf) It is the amount of potential necessary to cause 1 coulomb to produce 1 joule of work. It is the pressure of an electrical circuit.
What is an ohm?
It is the unit of resistance to current flow.
What is a watt?
A watt is the amount of power used in a circuit. It is the measure of true power
What is a permanent magnet?
Are magnets that do not require any power or force to maintain their field.
What are magnetic materials?
- Ferromagnetic material- a metal that is easily magnitized ex. Iron, nickel, cobalt, manganese
- Paramagnetic material- metals that can be magnitized but not as easily as ferromagnetic metals. Ex. Platinum, titanium, and chromium
- Diamagnetic material- metal or non metal materials that can’t be magnetized. Ex. Copper, brass
What is electromagnetic?
Law that states that whenever an electric current flows through a conductor a magnetic field is formed around the conductor.
What determines the number of flux lines by an electromagnetic?
Number of turns of wire and the current flow.
What is permeability?
The measure of a materials ability to become magnitized.
What is reluctance?
Is the resistance to magnatism.
What is saturation?
When all the molecules of the magnetic material are lined up.
What is coercive force?
Is the measure of a materials ability to retain magnetism.
What is flux density?
In the english system, the measure for magnetic strength
How do you demagnetize?
- Place item in a/c magnetic fields
- Hit item
- Heat item
What is a variable resistor and name two.
A resistor whose values can be changed or varied. Potentiometer and rheostat.
Name the laws of series.
- The current is the same at any point in the circuit.
- The total resistance is the sum of the individual resistors.
- The applied voltage is equal to the sum of the voltage drops across all the resistors.
Name the laws of parallel.
- The total current flow in the circuit is equal to the sum of the currents through all the branches.2. The voltage drop across any branch of a parrallel circuit is the same as the applied voltage.
- Total resistance of a parrallel Circuit is always less than the resistance of the lowest value resistor.
What is cell voltage?
The amount of voltage produced by an individual cell is determined by the materials from which it is made.
What is a primary cell?
Is a cell that cannot be recharged. The chemical reaction causes one of the electrode to be eaten away as power is produced. When the cell becomes discharged it should be replaced.
Explain current capacity
The amount of current a particular type of cell can deliver is determined be the surface area of its plates
What is specific gravity?
Is a measure of the amount of acid contained in the water
What is a hydrometer?
A device used for measuring the specific gravity of a cell.
Charging cycle info
The terminal voltage of the power supply must be greater than that of the cell or battery. As current flows through the cell, hydrogen is produced at the negative plate and oxygen is produced at the positive plate.
What is a thermocouple?
A thermocouple is a device with two dissimilar metals that produce electricity with heat
What ia a fixed resistor?
A resistor with only one ohmic value, which cannot be changed or adjusted.
