2A672 Volume 1 Quiz

An element is the simplest form of matter because it consists of only one type of atom. It cannot be broken down into simpler substances by chemical means. In contrast, a mixture is a combination of two or more substances, and a compound is a substance made up of two or more different elements chemically combined. Electrons, on the other hand, are subatomic particles and not a form of matter on their own.

Valence electrons are the electrons in the outermost shell of an atom. These electrons are involved in chemical reactions and are responsible for the atom's ability to form bonds with other atoms. Since valence electrons are farther from the nucleus compared to other electrons, they experience less attraction from the positive charge of the nucleus. This results in valence electrons having higher energy levels compared to electrons in inner shells. Therefore, valence electrons contain the most energy in an atom.

Electromagnetic induction is the correct answer because when a magnetic field expands or collapses, it creates a change in magnetic flux through a conductor. This change in magnetic flux induces a voltage in the conductor according to Faraday's law of electromagnetic induction. This phenomenon is the basis for the generation of electric power in generators and is a fundamental principle in electromagnetism.

When the size of the plates of a capacitor is increased, the capacitance increases. This is because capacitance is directly proportional to the area of the plates. As the size of the plates increases, there is more surface area available for the electric field to store charge, resulting in an increase in capacitance.

The factors that affect the resistance of a material are the area, temperature, and type of material. The area of the material affects resistance because a larger area allows for more current to flow, resulting in lower resistance. The temperature of the material affects resistance because as the temperature increases, the resistance also increases. The type of material affects resistance because different materials have different resistivities, which determine how easily they allow current to flow.

A silicon-controlled rectifier (SCR) is primarily used as an electronic switch. It is a semiconductor device that can control the flow of electric current. When a small control current is applied to the gate terminal, the SCR allows a larger current to flow from the anode to the cathode. This makes it useful for applications where precise control of high-power AC or DC currents is required, such as in motor control, power supplies, and lighting systems. The SCR can turn on and off rapidly, making it an efficient and reliable electronic switch.

In an open circuit, there is no complete path for the current to flow, resulting in no current flow. On the other hand, in a short circuit, there is a direct connection between two points with very low resistance, causing excessive current flow. Therefore, the correct answer is "No current flow in an open circuit; excessive current flow in a shorted component."

The scavenge pump is responsible for drawing excess oil from the gear case in the -60A lubrication system on a gas turbine engine. This pump is designed to remove any oil that is not needed for lubrication and return it to the oil tank or cooler. By doing so, the scavenge pump helps to maintain the proper oil levels and prevent any potential damage or malfunction caused by an excessive amount of oil in the gear case.

When the B809A generator set AC card senses an AC supply fault, the AC contactor opens and the generator output stops. This means that the AC contactor, which is responsible for controlling the flow of electricity to the generator, opens or disconnects the circuit. As a result, the generator stops producing electrical output. This action is taken to protect the system from any potential damage or danger caused by the AC supply fault.

The torsion shaft is specifically designed to break if the gas turbine engine locks up. This component is designed to absorb and dampen torsional vibrations in the engine. If the engine locks up, excessive torsional forces can be exerted on the shaft, causing it to break and prevent further damage to the engine.

When the diameter of the core in an inductor is increased in size, it allows for more magnetic lines of force to pass through the coil. This increase in magnetic lines of force leads to a higher level of induction of the coil.

Atoms having more than four electrons, but less than eight are known as insulators. Insulators are materials that do not conduct electricity easily because their outermost electron shells are fully occupied or nearly fully occupied. This means that they have a stable electron configuration and do not readily gain or lose electrons to become charged ions. As a result, insulators have high resistivity and do not allow the flow of electric current easily.

The major difference between an NPN transistor and a PNP transistor is the direction of current flow. In an NPN transistor, the current flows from the collector to the emitter, while in a PNP transistor, the current flows from the emitter to the collector. This difference in current flow direction is due to the arrangement and doping of the semiconductor materials within the transistor.

The injector pump is the component on the B809A generator set fuel system that distributes and delivers an accurate amount of fuel to the engine cylinders. It is responsible for pressurizing the fuel and injecting it into the cylinders at the correct time and in the correct quantity to ensure efficient combustion. The injector pump plays a crucial role in maintaining the engine's performance and fuel efficiency.

The electrostatic fields around a positive ion move outward. This is because positive ions have a deficiency of electrons, resulting in an excess of positive charge. As a result, the positive charge is repelled and moves away from the ion, creating an outward flow of the electrostatic fields.

The correct answer is low lube pressure. The B809A generator set engine safety circuit incorporates a seven-second time delay before activation in order to prevent false alarms or unnecessary shutdowns. This delay allows the engine to stabilize and ensures that the low lube pressure condition is consistent before triggering the safety circuit. By incorporating this time delay, the engine is protected from potential damage or failure caused by insufficient lubrication.

A step-down transformer contains more turns in the primary winding than in the secondary winding. This type of transformer is designed to reduce the voltage level from the primary side to the secondary side. By having more turns in the primary winding, the transformer increases the voltage on the primary side and decreases it on the secondary side, resulting in a step-down effect. This is commonly used in power distribution systems to lower the high voltage from power plants to a safer and more usable level for homes and businesses.

The correct answer is (T1) and rectifier (CR26). In a voltage regulator, the exciter field voltage is supplied by a transformer (T1) and a rectifier (CR26). The transformer steps down the voltage from the main generator and the rectifier converts the AC voltage into DC voltage. This combination of T1 and CR26 ensures that the exciter field receives the appropriate voltage to regulate the output voltage of the generator.

Total current is equal throughout series part of circuit. So since I1 (in series part) = 9 amps, IT = 9 amps. Parallel branches always add up to equal current flow in series part. So, I2 (5 amps) + I3 (?) = 9 amps. I3 has to equal 4 amps.

To convert milliamps to standard amperage, you divide the value by 1000. In this case, 500 milliamps divided by 1000 equals 0.5 amps.

The probable cause of the excessively high exhaust gas temperature in a -60A could be a malfunctioning pneumatic thermostat. The pneumatic thermostat is responsible for regulating the temperature of the engine by controlling the flow of air and fuel. If it is not functioning properly, it may cause an imbalance in the air-fuel mixture, leading to higher exhaust gas temperatures.

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Mutual induction is the basic principle of operation for transformers. This principle states that when the current in the primary coil of a transformer changes, it creates a changing magnetic field. This changing magnetic field induces a voltage in the secondary coil, which can then be used to transfer electrical energy from one circuit to another. Mutual induction allows transformers to efficiently increase or decrease the voltage of an alternating current while maintaining power conservation.

Find RT of parallel resistors: RT = 8x8/8+8 = 64/16 = 4
New R2 is RT of parallel resistors. Now use RT = R1 (7) + R2 (4) = 11 ohms

40/2^2 = 40/4 = 10 ohms

The DC card on the B809A generator set senses the condition of overtemperature. This means that the card is able to detect when the temperature of the generator set exceeds a certain threshold. This is an important feature as it helps prevent overheating and potential damage to the generator set. By sensing overtemperature, the DC card can trigger appropriate actions such as shutting down the generator set or activating cooling mechanisms to ensure safe and efficient operation.

The emitter in a unijunction transistor always points toward the base 1 lead. This is because the base 1 lead is the terminal that controls the current flow through the transistor. By pointing the emitter towards the base 1 lead, the transistor is able to regulate the current effectively. The emitter is responsible for emitting the majority charge carriers, and by aligning it with the base 1 lead, the transistor can function properly and perform its intended tasks.

When a small potential is applied to the gate of an SCR, it causes the middle junction of the SCR to become forward biased. This means that the voltage at the gate is higher than the voltage at the cathode, allowing current to flow through the SCR and turning it on.

A zener diode is connected in parallel to the load in order to regulate voltage. When connected in this manner, the zener diode acts as a voltage regulator by maintaining a constant voltage across the load, regardless of variations in the input voltage. This is achieved by allowing current to flow through the zener diode in the reverse direction when the voltage exceeds the zener breakdown voltage. This ensures that the voltage across the load remains constant, providing a stable power supply for the circuit.

The three leads in a unijunction transistor (UJT) are called emitter, base 1, and base 2.

The valence band of an intrinsic semiconductor has 4 electrons. In an intrinsic semiconductor, the valence band is completely filled with electrons at absolute zero temperature. Each electron in the valence band is bonded to its respective atom's nucleus, creating a stable lattice structure. These valence electrons are responsible for the semiconductor's electrical conductivity.

If the arrow in a bipolar transistor is pointing away from the base, it indicates that the transistor is an NPN type. In an NPN transistor, the majority charge carriers are negative electrons, hence the arrow pointing away from the base represents the flow of electrons from the emitter to the base and then to the collector.

The voltage regulator VR1 controls the strength of the -86D exciter field L2. This means that it regulates the voltage supplied to the exciter field, which in turn determines the strength of the field. By adjusting the voltage, the voltage regulator can control the output of the exciter field and ensure that it is at the desired level.

The probable cause of the undervoltage light coming on when placing S13 in the build up position while operating a -86D at governed speed is the memory time delay relay.

Apparent power is a measure of the total power in an electrical circuit, including both the real power (measured in kilowatts) and the reactive power. It is expressed in kilo-volt-amperes (KVA) because it represents the product of the voltage (measured in kilovolts) and the current (measured in amperes) in the circuit. This unit is used to quantify the total power that is being supplied or consumed by a device or system, taking into account both the real and reactive components of power.

During the first cycle of alternating current (AC) in a circuit using a bridge rectifier, two diodes are forward biased. A bridge rectifier consists of four diodes arranged in a bridge configuration. During the positive half cycle of the AC input, two diodes (D1 and D2) become forward biased and conduct current, while the other two diodes (D3 and D4) are reverse biased and do not conduct. This allows the positive half cycle of the AC input to pass through the circuit. Therefore, the correct answer is 2.

The probable cause of the unit operating at only 97 percent is the governor trim control. The governor trim control is responsible for adjusting the fuel flow to maintain the desired speed of the unit. If the governor trim control is not functioning properly, it may not be able to adjust the fuel flow accurately, resulting in the unit operating at a lower percentage than desired.

In P-type material, the majority carriers are holes, which are positively charged. Minority carriers, on the other hand, are the minority of charge carriers in the material. In P-type material, the minority carriers are electrons, which are negatively charged. These electrons are present due to the doping of the material with impurities, which introduces extra electrons into the crystal lattice.

If the emitter-base current is increased in a transistor amplifier, it will cause the current to increase through the emitter-collector (E-C) circuit. This is because the emitter-base junction acts as a current amplifier, and an increase in the input current will result in a proportional increase in the output current through the E-C circuit.

A unijunction transistor (UJT) typically has only one junction. This junction is formed between the emitter and the base regions of the transistor. The UJT operates by controlling the current flow between the emitter and the base junction, which in turn controls the current flow between the emitter and the collector terminals. Therefore, the correct answer is 1, as there is only one junction in a UJT.

The power factor meter is used during performing resistive and reactive load tests simultaneously. This is because resistive load tests only measure true power, while reactive load tests measure both true power and apparent power. Therefore, using a power factor meter allows for accurate measurement of both types of power during these tests.

The area where P-type material is joined to N-type material in a semiconductor is known as the depletion region. This region is depleted of majority carriers due to the diffusion of minority carriers from both sides, creating a region with no free charge carriers. The depletion region acts as a barrier to the flow of current and plays a crucial role in the operation of semiconductor devices such as diodes and transistors.

If the -86D power unit has all the fault lights on and resetting S23 does not fix the issue, a probable cause of this trouble could be that S30 is shorted. A shorted S30 would prevent the fault lights from turning off even after attempting to reset S23.

A junction diode has only one PN junction. A PN junction is formed by the combination of a P-type semiconductor and an N-type semiconductor, creating a boundary between the two regions. This junction is responsible for the diode's characteristic behavior, allowing current to flow in one direction while blocking it in the opposite direction. Therefore, a junction diode has one PN junction.

The operating voltage of the blower motor and control relays on a -8 load bank is 28 VDC.

A capacitive circuit is characterized by the fact that the current leads the applied voltage by 90 degrees. This means that the current reaches its maximum value before the voltage does, and the phase angle between the current and voltage is 90 degrees. This behavior is typical of capacitors, which store and release energy in response to changes in voltage.

If a schematic diagram doesn't list a reference for the zener diode, it is likely being used as a spike protector. A spike protector is a device that protects electronic circuits from voltage spikes or surges. Zener diodes are commonly used in spike protection circuits because they have a breakdown voltage that allows them to conduct when the voltage exceeds a certain threshold. By diverting excessive voltage away from the circuit, the zener diode helps to protect the components from damage. Therefore, if a schematic diagram doesn't specify the purpose of the zener diode, it is reasonable to assume that it is being used as a spike protector.

The line drop switch must be placed in the ON position when adjustments are made to a voltage regulator. This is because the ON position allows the flow of electricity through the regulator, enabling adjustments to be made to the voltage output. Placing the switch in the OFF position would interrupt the flow of electricity and prevent any adjustments from being made. The Adjust and Regulator options are not relevant to the position of the line drop switch.

The oil pressure relief valve in the lubrication system of the -60A gas turbine engine controls the output of the main oil pump by bypassing excess oil back to the main pump inlet. When the oil pressure exceeds a certain threshold, the relief valve opens, allowing the excess oil to flow back into the inlet of the main pump. This helps regulate the oil pressure and prevents it from becoming too high, ensuring proper lubrication and preventing damage to the engine components.

The zener diode is connected in parallel to the load in order to protect it. When the voltage across the load exceeds the breakdown voltage of the zener diode, it starts conducting in reverse bias and limits the voltage across the load. This prevents the load from being damaged by excessive voltage.