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Fuels Vol. 1 Unit 4
Electrical Fundamentals and Circuit Testing
| Question | Answer |
|---|---|
| what is the outermost shell of an atom called and what are the electrons there callled | valence shell and valence electrons |
| what is a substance that permits a large number of free electrons to move through it | conductor |
| what is a substance that has few free electrons | insulator |
| what is the uniform movement of electrons in a specific direction through a conductor | electric current |
| the unit of measure for current flow is | ampere (amp) |
| what is used to measure amps or current flow | an ammeter, or a multimeter |
| what are the four effects of electrons flowing through an electric circuit | heat, chemical change, magnetism, and physical shock |
| what is the force that moves the electrons from one atom to another | volatage (volt) |
| instrument used to measure voltage is | voltmeter |
| a device for producing a voltage by chemical reaction | battery |
| produces voltage by changing mechanical energy to electrical energy | generator |
| two different metals joined together that are heated and allow heat energy to be changed into electrical energy and produces current flow | thermocouple |
| generate electricity when photons reach a semiconducting material | solar cell |
| the compression or decompression of certain substances in their __ form generates voltage | crystallized |
| opposition to current flow that is offered by a material is called | resistance |
| 1 volt of pressure pushes 1 ampere of current flow through an electrical path, then 1 __ of resistance is present | ohm |
| 5 factors that affect resistance | conductor length, conductor size, conductor material, temperature, reactance |
| what reactance generated by the magnetic field of the coils causes the current to lag behind the voltage | inductive |
| what reactance generated as electricity passes through the plates within the capacitor, causing the current to lead the voltage | capacitive |
| type of magnet composed of a black mineral called iodestone or magnetite | natural |
| man-made magnets | artificial or permanent |
| objects magnetized by being placed in a magnetic field created by an electric current | electromagnets |
| fundamental law of magnets states that like poles __ each other, unlike poles __ each other, and the lines of force do not __ each other | repel, attract, cross |
| 3 items that comprise an electromagnet | coil of wire, a core material, and current flow in the coil |
| main difference in DC and AC voltage is the | direction of current flow |
| in what circuit does current move in one direction from the negative terminal of the source, through the circuit, then to the positive terminal | DC circuit |
| what current changes its flow first in one direction and then in the other direction | alternating |
| what type of generator changes mechanical energy to electrical energy by the principle of electromagnetic induction | AC generator |
| an AC generator is a major source of AC voltage. it requires 3 things: | magnetic field, conductor, relative motion |
| the number of times each electrical cycle occurs in 1 second is called | frequency (hertz) |
| the frequency of the AC-generator voltage output depends on the speed of rotation of the __ and the number of pairs of __ | rotor, poles |
| who puts out the standardized symbols used for electrical blueprints and drawings | American National Standard Institute (ANSI) |
| what are used with floor plans to clarify the symbols used on a particular drawing | legend |
| what are used to clarify information shown on the drawings | specifications |
| defined as a line drawing that shows arrangements or relationship of parts | diagram |
| the four types of electrical diagrams | block, wiring, connection, and schematic |
| what diagram is a simple drawing showing the relationship of major parts of a system | block diagram |
| what diagram uses pictures of components instead of blocks and shows the wiring between components and the relative position of those components | wiring diagram |
| diagram that shows the internal and external circuit connections | connection digram |
| drawing that shows the electrical plan of operation of a piece of equipment or component | schematic diagram |
| as little as __ milliamperes can kill you | 100 |
| a common multimeter that the AF uses is the | Fluke 8025A Multimeter |
| what term means that you do not have to open the circuit to connect the multimeter between two wires or connections | "in parallel" |
| when checking voltage on a 3-phase motor, if each leg is supposed to have __ volts, a voltage measurement of less than plus or minus __ percent is acceptable | 120 volts, 10% |
| used to check the resistance of a unit or a circuit | ohmmeter |
| a reading of __ ohms across a fuse is indicative of no resistance and a good fuse | zero (0) |
| a reading of __ ohms across a fuse indicates a break in continuity or a bad fuse | infinity |
| before taking a measurement using an ohmmeter, zero the meter by touching the __ and __ test leads together | red and black |
| used to check the current flow of a unit or a circuit | ammeter |
| easiest to use when measuring current flow b/c you do not have to interrupt the circuit to connect the meter "in series" in order to take the current readings | clamp-on type ammeter |
| worn out motor bearings due to improper lubrication, pump bearings going bad or a flow restriction, a change in load for which it was intended, and potential motor winding problems are all causes of what | abnormal motor amperage |
| formula for determining current is | voltage/resistance |
Created by:
Scottydick
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