2024 Dale Crane General Updated Exam

What constitutes a capacitor? - ANSWER- Two conductors separated by an insulator. What is the purpose of a capacitor? - ANSWER- It stores electrical energy in electrostatic fields. Does a capacitor in an AC cause the current to lead or lag the voltage? - ANSWER- It causes the current to lead the voltage. What is the basic unit of capacitance? - ANSWER- The farad. Why should electrolytic capacitors not be used in an AC circuit? - ANSWER- They are polarized, An electrolytic capacitor will pass current of one polarity, but will block current of the opposite polarity. What is meant by inductance? - ANSWER- The ability to store electrical energy in electromagnetic fields. What is the basic unit of inductance? - ANSWER- The henry. What is an example of an inductor used in a magneto? - ANSWER- The coil. Does an inductor in an AC circuit cause the current to lead or lag the voltage? - ANSWER- It causes the current to lag behind the voltage. How can you find the polarity of an electromagnet? - ANSWER- Hold the electromagnet in your left hand with your fingers encircling the coil in the direction electrons flow ( from negative to positive ). Your thumb will point to the north pole of the electromagnet. What is meant by impedance? - ANSWER- The total opposition to the flow of alternating current. It is the vector sum of resistance, capacitive reactance and inductive reactance. In what units is impedance measured? - ANSWER- In Ohms. What are five sources of electrical energy? - ANSWER- Magnetism, chemical energy, light, heat and pressure. What is the basic unit of power in a DC circuit? - ANSWER- The Watt. What is meant by kilowatt? - ANSWER- 1,000 watts. What is meant by a megawatt? - ANSWER- 1,000,000 watts. What is the formula for power in a DC circuit? - ANSWER- Power= Voltage times Current (P = E • I). What is the relationship between mechanical and electrical power? - ANSWER- 1 Horsepower = 746 Watts. What is meant by true power in an AC circuit? - ANSWER- The product of circuit voltage and the current that is in phase with this voltage. In what units is true power expressed? - ANSWER- In watts. What is meant by apparent power in an AC circuit? - ANSWER- The product of the circuit voltage and the circuit current. In what units is apparent power expressed? - ANSWER- In Volt-amps. What is meant by reactive power in an AC circuit? - ANSWER- The power consumed in the inductive and capacitive reactances in an AC circuit. Reactive power is also called wattless power. In what unit is reactive power expressed? - ANSWER- In volt-amps reactive (VAR), or kilovolt-amps reactive (KVAR). What is meant by power factor in AC circuit? - ANSWER- The ratio of true power to apparent power. It is also the ratio of circuit resistance to circuit impedance. Which law of electricity is the most important for an aircraft mechanic to know? - ANSWER- What are the elements of ohm's law Ohm's law. What is voltage? - ANSWER- Electrical pressure. What is the basic unit of voltage? - ANSWER- The volt. What instrument is used to measure voltage? - ANSWER- A voltmeter To measure voltage, is a voltmeter placed in series or in parallel with the source of voltage? - ANSWER- In parallel. What is electrical current? - ANSWER- The flow of electrons in a circuit. What is the basic unit of current flow? - ANSWER- The ampere (amp) What part of an amp is a milliamp? - ANSWER- One thousandth (0.001) of an amp What instrument is used to measure current flow? - ANSWER- An ammeter. What two things happen when current flows through a conductor? - ANSWER- Heat is generated and a magnetic field surrounds the conductor. To measure current through a component, is an ammeter placed in parallel or in series with the component? - ANSWER- In series. What is meant by resistance in an electrical circuit? - ANSWER- The opposition to the flow of electrons. What is the basic unit of electrical resistance? - ANSWER- The ohm. What is a megohm? - ANSWER- One million (1,000,000) ohms. What four things affect the resistance of electrical conductor? - ANSWER- The material, the cross-sectional area, the length and the temperature. What instrument is used to measure electrical resistance? - ANSWER- An ohmmeter. How can you tell the resistance of a composition resistance? - ANSWER- By a series of colored bands around one end of the resistor. What is meant by continuity in an electrical circuit? - ANSWER- The circuit is continuous (or complete) when electrons can flow from one terminal of the power source to the other. What is the instrument is used to measure continuity in an electrical circuit? - ANSWER- An ohmmeter. When measuring resistance of a component with an ohmmeter, should the circuit be energized? - ANSWER- No, there should be no power on the circuit. What are three things must an electrical circuit contain? - ANSWER- A source of electrical energy, a load to use the energy and conductors to join the source and the load. What are three types of DC circuits with regard to the placement of the various circuit components? - ANSWER- Series, parallel and series-parallel What is the name of the law that describes the relationship in an electrical circuit of voltage, current and resistance? - ANSWER- Ohm's law. What is the basic equation of ohm's law? - ANSWER- E= I×R