AMNT 260 Week 3 Quiz.docx. 100% CORRECT

The is the basic unit of inductance. farad henry coulomb A good capacitor passes DC. Correct Answer blocks DC. blocks AC. Inductive reactance is measured in henrys watts ohms One cycle of alternating current consists of one alternation. a positive and negative peak value. Correct Answer two alternations. True power is measured in farads. watts. volt-amps. The I in Ohm’s Law equals voltage in amperes. resistance in ohms. current in amperes. When measuring expected voltage or current, select a scale that is on a multimeter. higher mid-scale lower Kirchhoff’s voltage law states that the algebraic difference of all voltages around a closed path or loop is one. algebraic difference of all voltages around a closed path or loop is zero. algebraic sum of all voltages around a closed path or loop is zero. Total power equals the sum of power dissipated in each resistor. volts divided by resistance. the sum of power dissipated in one resistor. What do you get if power and time are multiplied together? Joules Watts Energy Current flow in one direction is called alternating current. direct current. potential difference. The primary difference between the series circuit and the parallel circuit is that more than one path is provided in the parallel circuit. more than one path is provided in the series circuit. only one path is provided for current in the parallel circuit. Ions with like charges are balanced. repel each other. attract each other. Which is an example of a compound? Water Oxygen Iron What gives an atom its electrical characteristics? Chemical elements Valence electrons Free electrons Static electricity Correct Answer is uncontrollable and unpredictable. reverses direction of flow. always flows in the same direction. For the purpose of an aircraft technician, what are the categories of matter that are considered? Matter, weight, and gravity Mass, liquids, and plasma Solids, liquids, and gases Silicon and germanium are mostly used in conductors. semiconductors. insulators. Static wicks are a fire hazard. bleed off static charges. provide static interference in radio equipment. Electrical pressure is measured in volts. amps. ohms. Electricity produced by magnetism is direct current. Correct Answer alternating current. a chemical process. The thumb in the left-hand rule Correct Answer points in the direction of current flow. signifies the direction of the lines of the magnetic field. points in the direction of resistance. Transfer of electric energy from one circuit to another without the aid of electrical connections is called induction. is called capacitance. can cause excessive arcing and heat, and as a result is practical for use only with low voltages/amperages. The continually changing current in an AC circuit causes a changing magnetic field to cut across conductors in an adjacent circuit. When the changing field cuts across a conductor, it induces a voltage in it. Induction allows electrical energy to be transferred from one circuit to another without the aid of electrical connections. What is the total capacitance of a circuit containing three capacitors in parallel with capacitances of .02 microfarad, .05 microfarad, and .10 microfarad, respectively? Correct Answer .170 uF. 0.125 pF. .0125 uF. Use the formula Ct = C1 + C2 + C3. When capacitors are connected together in parallel, the plate area of all the capacitors add together and the total capacitance is the sum of the individual capacitances. .02 + .05 + .10 = .170 uF. The term that describes the combined resistive forces in an ac circuit is resistance. impedance. reactance. Impedance, whose symbol is Z, is the combined resistive force in an AC circuit. There are three types of resistive forces in an AC circuit: inductive reactance, which causes the current to lag the voltage, capacitive reactance, which causes the current to lead the voltage, and resistance, which allows the current and voltage to remain in phase. Inductive and capacitive reactance are 180° out of phase, and they cancel each other. Impedance is the vector sum of the resistance and the total reactance in the circuit; it is expressed in ohms and is found by the formula: Z = The square root of (R^2 + X^2) Unless otherwise specified, any values given for current or voltage in an ac circuit are assumed to be maximum values. effective values. instantaneous values. Almost all measuring instruments used for electrical system servicing measure the effective (rms) values of alternating current. Unless peak values, peak-to-peak values, or average values are specifically called out, effective values are assumed. Electrostatic fields are also known as Electrostatic fields. Static fields. Dielectric fields. A field of force exists around a charged body. This is an electrostatic field (sometimes called a dielectric field) and it is represented by lines that extend in all directions from the charged body which terminate where there is an equal and opposite charge. Refer to Figure 3: When more than two inductors of different inductances are connected in parallel in a circuit, the total inductance is equal to the sum of the individual inductances. less than the inductance of the lowest rated inductor. equal to the inductance of the highest rated inductor. When two or more inductors having different inductances are connected in parallel, the total inductance is less than the inductance of the lowest rated inductor. Capacitors are sometimes used in dc circuits to counteract inductive reactance at specific locations. smooth out slight pulsations in current/voltage. assist in stepping voltage and current up and/or down. Capacitors store electrical charges and are sometimes used in DC circuits to smooth out slight pulsations in the current or voltage. They accept electrons when there is an excess and release them back into the circuit when the values decrease. When calculating power in a reactive or inductive ac circuit, the true power is less than the apparent power in a reactive circuit and more than the apparent power in an inductive circuit. more than the apparent power. less than the apparent power. True power in an AC circuit is the product of the circuit voltage and only that part of the current in phase with the voltage. Apparent power is the circuit voltage multiplied by all of the current. True power is always less than the apparent power in a reactive circuit which is any AC circuit containing either inductance or capacitance. When inductors are connected in series in a circuit, the total inductance is (where the magnetic fields of each inductor do not affect the others) (Note: L(T) = L(1) + L(2) + L(3) . . .) equal to the sum of the individual inductances. less than the inductance of the lowest rated inductor. equal to the inductance of the highest rated inductor. When several inductors are connected together in such a way that there is no inductive coupling, the total inductance is the sum of the individual inductances. The basis for transformer operation in the use of alternating current is mutual inductance. capacitance. reactance. A transformer operates on the basis of mutual inductance. The changing current in the primary windings produces a changing magnetic field whose flux cuts across the turns of the secondary winding and induces a voltage into it. Which effect does not apply to the movement of electrons flowing in a conductor? Correct Answer Static energy. Magnetic energy. Thermal energy. Current flowing through a conductor produces a magnetic field and also dissipates thermal energy. The voltage drop in a circuit of known resistance is dependent on the voltage of the circuit. the amperage of the circuit. only the resistance of the conductor and does not change with a change in either voltage or amperage. The voltage drop across a circuit is determined by two things: the resistance of the conductor and the amount of current flowing through it (the amperage). In this question, the resistance of the circuit is fixed; therefore, the voltage drop is determined by the amperage in the circuit. Which requires the most electrical power? (Note: 1 horsepower = 746 watts) Four 30-watt lamps arranged in a 12-volt parallel circuit. A 1/5-horsepower, 24-volt motor which is 75 percent efficient. A 24-volt anticollision light circuit consisting of two light assemblies which require 3 amperes each during operation. The 1/5-horsepower motor operating at 75 percent efficiency uses 198.93 watts of power. The four 30-watt lamps use 120 watts of power. The anticollision light circuit uses 144 watts of power. What is the operating resistance of a 30-watt light bulb designed for a 28- volt system? 1.07 ohms. 26 ohms. 0.93 ohm. A 30-watt light bulb operating in a 28-volt electrical system has a hot resistance (operating resistance) of 26.13 ohms. R = E^2 Õ P = 28^2 Õ 30 = 26.12 omega Refer to Figure 11: Find the total current flowing in the wire between points C and D. 6.0 amperes. 2.4 amperes. Correct Answer 3.0 amperes. The total resistance between points D-E and G-H is 8 ohms. This is the resistance of resistors R(2) and R(3) in parallel. There is a voltage of 24 volts across these two parallel resistors, so the current through the line between C and D is three amps. Question 38 2 / 2 pts A 1-horsepower, 24-volt dc electric motor that is 80 percent efficient requires 932.5 watts. How much power will a 1-horsepower, 12-volt dc electric motor that is 75 percent efficient require? (Note: 1 horsepower = 746 watts) 1,305.5 watts. 932.5 watts. 994.6 watts. When we know the horsepower output and the efficiency of an electric motor, the voltage does not enter into the computation. To find the number of watts required, divide the wattage for the total horsepower by the decimal equivalent of the efficiency. 746 Õ 0.75 = 994.6 watts Which term means .001 ampere? Kiloampere. Milliampere. Microampere. The metric prefix 'milli-' means one thousandth. 0.001 ampere is one milliampere. In a parallel circuit with three 6-ohms resistors across a 12-volt battery, what is the total current (It) value in the circuit? 12 amps. 2 amps. 6 amps. The total resistance of this circuit is 2 ohms. The total current flowing in this circuit is 6 amps. A 12-volt electric motor has 1,000 watts input and 1 horsepower output. Maintaining the same efficiency, how much input power will a 24-volt, 1- horsepower electric motor require? (Note: 1 horsepower = 746 watts) 1,000 watts. 2,000 watts. 500 watts. The power produced by an electric motor is the product of its voltage and its current. A 12-volt motor will require 83.3 amps of current for its 1,000 watts of input power to produce 746 watts (1 horsepower) of output power. A 24- volt motor operating at the same efficiency will also require 1,000 watts of input power for its 746 watts of output power, but it will need only 41.7 amps of current. Convert farads to picofarads by: multiplying microfarads by 10 to the power of -12. multiplying picofarads by 10 to the power of 12. multiplying farads by 10 to the power of 12. Each farad is equal to 10^12 picofarads. Example: 2 farads is equal to 2 x 10^12 (2,000,000,000) picofarads. Which requires the most electrical power during operation? (Note: 1 horsepower = 746 watts) Two lights requiring 3 amperes each in a 24-volt parallel system. A 12-volt motor requiring 8 amperes. Four 30-watt lamps in a 12-volt parallel circuit. The 12-volt motor requires 96 watts of power. The four 30-watt lamps require 120 watts of power. The two 24-volt, 3-amp lights require 144 watts of power. What is the basic unit of electrical quantity? Electromotive Force. Correct Answer Coulomb. Ampere. The coulomb is the basic unit of electrical quantity. 1 coulomb is equal to 6.28 X 10^18 electrons. Refer to Figure 14: The total resistance of the circuit is 25 ohms. 35 ohms. 17 ohms. The total resistance can be found in two steps: 1. Combine resistances R(2), R(3), and R(4) in parallel. 2. Combine resistances R(1), R(2-3-4), and R(5) in series. Which is correct in reference to electrical resistance? Two electrical devices will have the same combined resistance if they are connected in series as they will have if connected in parallel. An electrical device that has a high resistance will use more power than one with a low resistance with the same applied voltage. If one of three bulbs in a parallel lighting circuit is removed, the total resistance of the circuit will become greater. In a parallel electrical circuit, each bulb provides a path for current to flow. The more paths there are, the less the circuit resistance will be. When one bulb is removed, the circuit resistance increases. Refer to Figure 13: Determine the total current flow in the circuit. 1.4 amperes. 0.8 ampere. 0.2 ampere. The total resistance of this circuit is 8.57 ohms. The total current flowing in this circuit is 1.4 amps. Question 48 2 / 2 pts Refer to Figure 10: What is the measured voltage of the series-parallel circuit between terminals A and B? 3.0 volts. 4.5 volts. 1.5 volts. The two batteries on the left side are connected in series, and the two batteries on the right side are connected in series. The two pairs of batteries are connected in parallel. The series connections between terminals A and B give this circuit a voltage of 3.0 volts. .002KV equals .2 volt. 20 volts. 2.0 volts. A KV is a kilovolt, or 1,000 volts. Two thousandths (.002) of a kilovolt is equal to 2.0 volts. Which is correct concerning a parallel circuit? Total resistance will be smaller than the smallest resistor. Total voltage drop is the same as the total resistance. Total resistance will decrease when one of the resistances is removed. In a parallel circuit each resistor forms a path for the current to follow and the total resistance is always smaller than that of the smallest resistor.