Navy Aviation Machinist Mate A School Key Revision Questions and Correct Answers 2024

Electricity - The physical phenomena arising from the existence and interaction of an electrical charge Voltage / Electromotive Force (EMF) - The amount of force being applied to a circuit to produce an electron flow Amperage / Current Flow - The quantity of electricity flowing through the circuit Resistance - The opposition to the flow of electrons offered by a device or material Ohms - The measurement of resistance to current flow Watt - The measurement of electrical work done Forms of Electricity - Static and Dynamic Static Electricity - (1) Electricity at rest (2) Begins with a build up of either a positive or negative electron charge. If two negative charges or two positive charges are brought close together, the objects that hold that charge repel each other. If a positive charge is brought within close proximity of a negative charge, the two objects attract each other (3) Static electricity is produced by friction and is not easily measured nor is it controllable or usable Dynamic Electricity - A practical form of current flow that is used in everyday life. This form of electricity is easily produced, measured, and controlled Methods of Producing Dynamic Electricity - Mechanical, Chemical, Thermal, and Pressure Mechanical - Produced by rotating a magnetic field through another magnetic field Ex: A Grass Cutter Chemical - Produced by surrounding two or metallic plates with a chemical electrolyte Ex: A Battery Thermal - Produced by joining two dissimilar metals and applying heat Ex: Thermocouple Pressure - Produced by applying pressure to quartz, which will produce an electron flow Ex: A Watch Types of Electricity - AC and DC Direct Current (DC) - Current that is a steady flow in one direction only. It is produced mechanically by a DC generator, or chemically by a battery Ex: A Flashlight Alternating Current (AC) - Current flow that reverses direction at specific intervals, defined as Hertz / Cycles. It is produced mechanically by an AC generator