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Self-Test 1 Q&A 3-3
Self-Test Questions Volume 1
Question | Answer |
---|---|
Describe matter | Any substance that has weight and takes up space |
What cannot be broken down into a simpler substance using ordinary chemical means? | Elements |
Define molecule | The smallest part of a substance that has all the characteristics of that substance |
What are the elements that form molecules? | Atoms |
What type of charge does a proton carry? An electron? | Protons carry a positive charge. Electrons carry a negative charge. |
When is an atom considered electrically balanced? | When the negative charge of the electron is equal to the positive charge of the proton. |
Describe electrical current | The uniform movement of electrons in a specific direction through a conductor (wire). |
What is the term for an atom with eight electrons in the valence shell? | Stable or balanced atom. |
What type of charge does a normal atom that has lost one electron have? | Positive |
What is an atom that has gained an electron called? | Negative ion. |
The uniform movement of free electrons in a specific direction | Current flow |
6.28 x 10^18 electrical charges | Coulomb |
One coulomb passing a given point per second | Ampere |
Symbol for current used in equations | I |
Symbol for quantity of amperes | A, a |
List the four effects of electrons flowing through an electric circuit | Heat, chemical change, magnetism, and physical shock. |
Unit of measure for “electrical pressure.” | Volt |
The force which causes electrons to move from atom to atom | Voltage or emf |
The symbol “E” when used in formulas | Voltage |
Changes mechanical energy into electrical energy | Generator |
Changes heat energy into electrical energy | Thermocouple |
Unit of measure for all electrical opposition | Ohm |
"When 1 volt of pressure pushes 1 ampere of current flow through an electrical path, then 1 ohm of resistance is present" | Ohm’s Law |
“R.” | The symbol for resistance in a math formula. |
Name five factors that affect resistance | Length of the conductor, Cross-sectional area of the conductor, Type of material the conductor is made of, Temperature, and Reactance. |
The rate of doing work | Power |
“W” or “P.” | “W” is the symbol for power in a drawing and “P” is the symbol for power in a math formula |
Unit in which electrical motors are rated | Horsepower |
Number of watts per horsepower | 746W |
Unit in which generators and regulators are rated | Watts |
State the fundamental law of magnetism | Like poles repel each other; unlike poles attract. |
When do magnetic lines of force cross? | Never |
What action takes place when you place the south pole of one magnet near the south pole of another? | They repel each other. |
What surrounds all current-carrying conductors? | Magnetic lines of force. |
How can you strengthen the magnetic lines of force around a conductor? | By forming a number of loops close together. |
What three items are necessary to have an electromagnet? | Coil of wire, core material, and current flow. |
What type of core is preferred in the construction of relays and solenoids? | Soft iron core |
Uses the principle of electromagnetic induction. Produced by a machine called a generator. Requires a magnetic field, electric conductor, and relative motion. | Mechanical Energy |
Develops a difference of potential between two unlike materials. Two unlike materials placed in an electrolyte. Wet cell and dry cell. | Chemical Energy |
Direct current. Electrons flowing in one direction. Used in emergency lighting. Produced by a battery | DC |
Alternating current. Slip rings used in a generator produce it | AC |