NCTI Installer Tech 100% SOLUTIONS REVISED 2023//2024

NCTI Installer Tech 100% SOLUTIONS REVISED 2023//2024 Why do only the outer electrons leave their orbit shells? - ANSWER Only outer electrons leave their orbit shells because electrons farthest from the nucleus are more easily freed from their orbits due to a weaker electrostatic force. What is required to have a balanced (or stable) atom? - ANSWER The number of electrons must equal the number of protons in order to have a balanced atom. List the capacity of each of the first four orbital shells of an atom. - ANSWER Shell: #1 = 2 electrons; #2 = 8 electrons; #3 = 18 electrons; and #4 = 32 electrons. What is the maximum electron capacity of a valence shell? - ANSWER A valence shell can hold a maximum of eight electrons. Electrons in orbits nearest the nucleus contain _________ energy than those in more distant orbits. - ANSWER Electrons in orbits nearest the nucleus contain less energy than those in more distant orbits. What will happen to a valence electron that has enough energy added to it? - ANSWER A valence electron that has enough energy added to it will move away from its atom. What major factor determines which category a particular element belongs? - ANSWER The number of electrons in the valence shell determines the element category. How many valence electrons are there in a good conductor? - ANSWER A good conductor has only one or two valence electrons. List gold, silver, and copper in the order of best conductivity. (List the best conductor first.) - ANSWER #1 Silver; #2 Copper; #3 Gold Why do metals that each have only one valence electron differ in their conductivity? - ANSWER Metals that each have one valence electron differ in their conductivity because of the way their atoms pack together into a solid structure. Describe the two characteristics of an insulator. - ANSWER The two characteristics of an insulator are as follows: 1. Its valence shell is almost filled and tends to be fairly stable. 2. It tries to finish filling its valence shell by capturing additional free electrons. How many valence electrons are in a semiconductor? - ANSWER A semiconductor has four valence electrons. Name the two types of electron current flow. - ANSWER Random drift and directed flow are the two types of electron current flow. What causes electrons to be knocked loose and travel randomly from one atom to another? - ANSWER The movement of atoms in materials that are conductors and the agitation as they collide cause electrons to be knocked loose and travel randomly from one atom to another. What can force electrons to all move in the same direction? - ANSWER Applying a negative charge to one end of the wire and a positive charge to the other can force electrons to all move in the same direction. The electrons in the wire will travel toward the positive charge as they are directed by the effects of the unlike charges. What actually produces electric current? - ANSWER The transfer of energy from valence electron to valence electron, as a result of applied charges, is what actually produces electric current. How does the speed of electric current compare to that of electron travel? - ANSWER The effective speed of electric current (186,000 miles per second) is much faster than the actual speed of electron travel (a few hundred miles per second). How many electrons are in one coulomb? - ANSWER A coulomb is equal to 6.28 × 1018 electrons. What is the basic measurement unit of electron current? - ANSWER The ampere is the basic measurement unit for electron current. Define ampere in terms of coulombs. - ANSWER An ampere is equal to 1 coulomb passing a given point during 1 second. Name the three terms that are used interchangeably to refer to the force that causes current flow. - ANSWER Potential difference, electromotive force (emf), and voltageare used interchangeably to refer to the force that causes current flow. Define electromotive force (emf). - ANSWER Emf is the electrical force that motivates electrons to move in a wire. What does the term potential difference mean? - ANSWER Potential difference is the algebraic difference between the electrical individual potentials of two points. What is the potential difference between two negative charges of equal value? - ANSWER The potential difference between two negative charges of equal value is zero. There is no potential difference. What is the unit used to indicate the strength or size of the potential difference? - ANSWER The volt is the unit used to indicate the strength or size of the potential difference. Define a volt in terms of current and resistance. - ANSWER One volt is the amount of force required to produce a current of 1 ampere through a resistance of 1 Ω. What are three alternate ways to express 5 µV and 3 mA? - ANSWER 5 microvolts, 5/1,000,000 volt or 0.000005 volt, and 3 milliamperes, 3/1,000 ampere or 0.003 A. What are two alternate ways to express 2 megavolts? - ANSWER 2 MV or 2 million