2A652 CDC Volume 2 Pretest

Resistance is used to control current flow in a circuit. Resistance is a property of a material that opposes the flow of electric current. It is measured in ohms and determines how much current will flow through a circuit for a given voltage. A higher resistance will result in less current flow, while a lower resistance will allow more current to flow. By adjusting the resistance in a circuit, the amount of current can be controlled.

Residual magnetism refers to the magnetism that remains in a material even after the magnetizing force has been removed. It is the property of certain materials to retain a magnetic field, which can be useful in various applications such as in the creation of permanent magnets. This phenomenon occurs due to the alignment of magnetic domains within the material, resulting in a net magnetic field that persists even without an external magnetic field.

A relay is an electrically operated switch. It is a device that controls the opening and closing of an electrical circuit by using an electromagnet to move a set of contacts. When the coil of the relay is energized, it creates a magnetic field that attracts the contacts, allowing current to flow through the circuit. When the coil is de-energized, the contacts return to their original position, interrupting the flow of current. Therefore, a relay acts as a switch, controlling the flow of electricity in a circuit.

The area around a magnet where its influence can be felt is known as the magnetic field. A magnetic field is a region in which a magnetic force is exerted on magnetic materials or moving electric charges. It is created by the movement of electric charges, such as the flow of current in a wire or the spinning of electrons in an atom. The strength and direction of the magnetic field can be visualized using magnetic field lines.

The magnetic field of an electromagnet can be varied by changing the type of core, number of turns in the coil, and the amount of current through the coil. The type of core affects the strength of the magnetic field as different materials have different magnetic properties. Increasing the number of turns in the coil increases the strength of the magnetic field as it increases the overall magnetic flux. Finally, increasing the amount of current through the coil increases the strength of the magnetic field as it increases the flow of electric charges and consequently the magnetic field. Therefore, all of the above factors can individually or collectively affect the magnetic field of an electromagnet.

Current is defined as the flow or drift of electrons through a conductor in the same direction at the same time. It is a measure of the rate at which electric charge flows in a circuit. Conductivity refers to the ability of a material to conduct electricity, while voltage is the difference in electric potential between two points. Valence, on the other hand, refers to the combining capacity of an element in a chemical reaction. Therefore, the correct answer is current, as it accurately describes the given definition.

An atom with eight electrons in its outermost shell is said to be stable. This is because the octet rule states that atoms tend to gain, lose, or share electrons in order to achieve a full outer shell of eight electrons. When an atom has a full outer shell, it is considered stable and less likely to react with other atoms.

In order to generate a voltage electromechanically, a magnetic field and relative motion are necessary. However, without a conductor, the flow of electrons required to create an electric current would not be possible. A conductor allows the movement of charged particles, such as electrons, which is essential for the generation of a voltage. Therefore, a conductor is required for electromechanical voltage generation.

The term "dielectric" is used to refer to insulators. Insulators are materials that do not conduct electricity easily and have high resistivity. They are commonly used to prevent the flow of electric current and to insulate electrical components. Dielectric materials are often used in capacitors, where they store electrical energy by creating an electric field between two conductive plates.

In a series circuit, the current flowing through the circuit is the same at all points. According to Ohm's Law, the current (I) can be calculated by dividing the voltage (V) by the resistance (R), using the formula I = V/R. Therefore, in this case, the current through the resistor can be calculated as 24 volts divided by 18 ohms, which equals 1.33 amps.

The systematic method is the best method of troubleshooting because it involves following a logical and organized approach to identify and solve problems. It helps in identifying the root cause of the problem by systematically analyzing and testing different components or variables. This method ensures that all possible causes are considered and eliminates guesswork or random attempts. It saves time and effort by providing a structured framework for troubleshooting, leading to more efficient and effective problem-solving.

Voltage is the correct answer because it refers to the potential difference between two points in a circuit. This potential difference creates an electric field that exerts a force on free electrons, causing them to move and creating an electric current. Conductivity refers to the ability of a material to conduct electric current, while current is the flow of electric charge. Valence, on the other hand, refers to the outermost shell of electrons in an atom.

When a soldering iron tip becomes pitted or worn, it can affect the quality of solder joints. To redress the tip, it should be tinned. Tinning refers to coating the tip with a thin layer of solder. This helps improve heat transfer and prevents oxidation of the tip. Tinning the tip also helps in creating a smooth and clean surface for soldering. Therefore, tinning is the correct answer for redressing a pitted or worn soldering iron tip.

A good conductor requires a small number of valence electrons to be able to easily move and carry electric charge. Valence electrons are the outermost electrons in an atom's electron shell, and they are responsible for the atom's chemical properties. Since only a few valence electrons are needed for a good conductor, the correct answer is 3.

The winding of a transformer that is connected to a power source is known as the primary winding. This is because the primary winding is responsible for receiving the electrical energy from the power source and transferring it to the secondary winding. The primary winding typically has a higher number of turns compared to the secondary winding, allowing it to step up or step down the voltage as required by the transformer.

In a capacitor, the dielectric is the insulator. The dielectric is a material that is placed between the two plates of the capacitor and it acts as an insulator, preventing the flow of electric current between the plates. It helps to increase the capacitance of the capacitor by storing more charge. The dielectric material can be made of various substances such as glass, ceramic, plastic, or even air.

A reference designation index is a troubleshooting aid that is designed to help you if you see an unfamiliar symbol. It provides a list of symbols and their corresponding meanings, allowing you to quickly identify and understand the symbol you are unfamiliar with. This can be particularly useful when working with complex systems or equipment that use specific symbols to represent different components or functions. By referring to the index, you can easily find the meaning of the symbol and use that information to troubleshoot and resolve any issues.

Electromagnetic induction is the principle behind all electromechanical generation. It is the process of generating an electric current in a conductor by moving it through a magnetic field or by varying the magnetic field around it. This phenomenon is used in various devices such as generators, transformers, and electric motors to convert mechanical energy into electrical energy or vice versa. Electromagnetic induction is based on Faraday's law of electromagnetic induction, which states that a change in magnetic field induces an electromotive force (EMF) in a conductor.

When performing a continuity check on a wire using the diode test mode, a good wire will register a beep. This is because a continuity check is used to determine if there is a complete path for the electric current to flow through the wire. If there is continuity, meaning the wire is not broken or damaged, the multimeter will produce a beep sound to indicate that the circuit is complete. Therefore, a beep is the expected result for a good wire during a continuity check in diode test mode.

When a light emitting diode (LED) is forward biased, it means that the positive terminal of the power supply is connected to the anode and the negative terminal is connected to the cathode of the LED. This causes the LED to conduct current and emit light. In this configuration, the energy levels of the LED's electrons are raised, allowing them to move across the junction and recombine with electron holes, releasing photons in the process. Therefore, forward biasing is the correct condition for an LED to produce light.

The best method of repairing a lifted circuit track on a printed circuit board (PCB) is to replace it with insulated wire. When a circuit track lifts or breaks, it creates a gap in the connection, disrupting the flow of electricity. By replacing it with insulated wire, the connection is restored, allowing the current to flow smoothly. Insulated wire provides protection and prevents any short circuits or interference with nearby components. Bonding or gluing may not provide a secure and reliable connection, while replacing it with bare wire can lead to potential short circuits.

Mutual induction is the process by which a current change in one coil induces a voltage in another coil. This phenomenon occurs when the magnetic field produced by one coil cuts across the turns of another coil, generating an electromotive force (EMF) in the second coil. This is the basis for the functioning of transformers and is widely used in various electrical devices and systems. Inductance refers to the property of a coil to oppose changes in current, while self-induction specifically refers to the production of a voltage in the same coil due to its own changing current.

Zones are a troubleshooting aid that is designed to aid you in finding components on a diagram. Zones divide a diagram into different areas, each representing a specific section or component. This helps in locating and identifying components quickly and efficiently, especially in complex diagrams with multiple components. By using zones, technicians can easily navigate through the diagram and pinpoint the exact location of the component they need to troubleshoot or repair.

A latching relay is a type of relay that, once energized, will maintain its state even after the initial input signal is removed. It requires a second coil to be energized in order to change its state and return the contacts to their original positions. This feature allows the latching relay to "lock" in its current state until a specific signal is received to change it.

When a diode is placed in reverse bias, it acts as a spike protector. In this configuration, the diode allows current to flow only in the reverse direction, blocking any spikes or surges in voltage that may occur in the circuit. This helps to protect the other components in the circuit from damage caused by these voltage spikes. Therefore, the diode is being used as a spike protector in this scenario.

A schematic is a troubleshooting aid that is designed to promote understanding of the system. It is a diagram that represents the components and connections of a system using standardized symbols. By studying the schematic, technicians can gain a clear understanding of how the system is designed and how its various components are interconnected. This understanding is crucial for troubleshooting and diagnosing issues within the system.

In a parallel circuit, the total resistance is calculated using the formula 1/Rt = 1/R1 + 1/R2 + 1/R3 + ... In this case, we have two branches with voltages of 440V and currents of 4A and 16A respectively. To find the resistance of each branch, we can use Ohm's Law: R = V/I. Therefore, the resistance of the first branch is 440V / 4A = 110 ohms, and the resistance of the second branch is 440V / 16A = 27.5 ohms. Plugging these values into the formula for total resistance, we get 1/Rt = 1/110 + 1/27.5 = 0.0091 + 0.0364 = 0.0455. Taking the reciprocal of this value gives us Rt = 22 ohms.

Biasing refers to the process of applying a DC voltage to a diode or transistor in order to establish a specific operating point. By applying a bias voltage, the depletion region of the diode can be either expanded or contracted, allowing or blocking the flow of current through the diode. Therefore, biasing is the correct term to describe the process of expanding or contracting the depletion region of a diode.

Electrostatic sensitive devices are identified by being marked with the MIL-STD-129 symbol or a caution marking. This marking indicates that the device is sensitive to electrostatic discharge and requires special handling to prevent damage. The MIL-STD-129 symbol or caution marking serves as a visual reminder to individuals that they need to take precautions when handling the device to avoid causing any electrostatic discharge.

In a parallel circuit, the source current is divided among the different branches based on their resistances. Each branch offers a different level of resistance, and the current flowing through each branch is inversely proportional to its resistance. Therefore, the branch with a higher resistance will have a lower current, while the branch with a lower resistance will have a higher current. This division of current based on resistances allows for independent functioning of the different branches in a parallel circuit.

A MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is a type of semiconductor device that has a gate that is not electrically connected to the rest of the device. The gate of a MOSFET is insulated from the channel by a thin layer of oxide, allowing it to control the flow of current between the source and drain terminals. This isolation of the gate from the rest of the device allows for better control and modulation of the current flow, making MOSFETs widely used in various electronic applications.

In a series-parallel circuit, the total current remains constant throughout the parallel portion of the circuit. This means that the current flowing through each branch in the parallel portion is the same. However, in the series portion of the circuit, the total current divides according to the resistance of each component. This means that the current flowing through each component in the series portion will be different, with more current flowing through components with lower resistance and less current flowing through components with higher resistance. Therefore, the correct answer is that the total current in a series-parallel circuit remains the same throughout the series part of the circuit and divides according to the branch resistance in the parallel portion.

When soldering flat perforated terminals, the conductor is connected to the terminal using a 180 degree wrap. This means that the conductor is wrapped around the terminal in a half-circle shape, covering half of the terminal's circumference. This wrap provides a secure and strong connection between the conductor and the terminal, ensuring good conductivity and minimizing the risk of the connection coming loose.

A transformer is an electrical device that can change the voltage of an alternating current (AC) while keeping the power constant. Power is the product of voltage and current, so if the voltage is changed by the transformer, the current will change accordingly to maintain the same power. Therefore, the correct answer is power because a transformer does not change the power, it only changes the voltage and current.

A capacitor stores energy in the form of an electrostatic field. When a voltage is applied across a capacitor, it causes a separation of charges, with positive charges accumulating on one plate and negative charges on the other plate. This separation of charges creates an electric field between the plates, which stores the energy. The energy is released when the capacitor is discharged, and the charges flow back to their original positions, converting the stored energy back into electrical energy.

The approximate operating voltage of a light emitting diode (LED) is 1.6 volts.

A heat sink is used in soldering to prevent heat from damaging other components in the circuit. When soldering, excessive heat can be generated, which can potentially damage nearby components. By using a heat sink, the heat is dissipated and spread out, preventing it from concentrating on a single component and causing damage. This helps to ensure the integrity and functionality of the other components in the circuit.

The correct answer is to make sure all electrostatic sensitive devices are properly marked. This is important because proper marking helps to identify and handle these devices correctly, reducing the risk of damage from electrostatic discharge. It ensures that everyone who interacts with these devices is aware of their sensitivity and takes necessary precautions to prevent any potential harm.

The correct answer is "wire touches the bottom". This means that the wire is inserted into the solder cup until it makes contact with the bottom of the cup. This ensures a secure and stable connection between the wire and the cup, which is important for proper electrical conductivity.

Once the avalanche point has been reached, a zener diode will start conducting in reverse bias. The avalanche breakdown occurs when the voltage across the diode exceeds its breakdown voltage, causing a rapid increase in the reverse current. This breakdown allows the zener diode to regulate the voltage across it by maintaining a constant voltage drop. Therefore, once the avalanche point is reached, the zener diode will conduct in reverse bias.

The emitter-base junction of a transistor is forward biased in normal operation. This means that the voltage at the emitter terminal is higher than the voltage at the base terminal. Forward biasing allows the flow of current from the emitter to the base, enabling the transistor to amplify and control the current flowing through the collector terminal. This biasing configuration is essential for the transistor to function properly and perform its intended tasks in electronic circuits.

A good solder cup connection shows the contour of the wire. This means that the solder has properly adhered to the wire, forming a smooth and even shape that matches the contour of the wire. This indicates that the solder joint is strong and secure, ensuring a reliable electrical connection.

Increasing the amount of motion would be the most difficult method to increase the output in a simple generator. This is because increasing the motion requires additional mechanical energy input, which can be challenging to achieve. On the other hand, increasing the area of the conductor, the strength of the magnetic field, or the relative resistance can be relatively easier to accomplish and would result in a more significant increase in the generator's output.

An SCR (Silicon Controlled Rectifier) has three PN junctions. A PN junction is formed when a P-type semiconductor material is joined with an N-type semiconductor material. In an SCR, there are two PN junctions between the P and N layers, and an additional PN junction between the gate and cathode. These junctions allow the SCR to control the flow of current in a circuit, making it a three-junction device.

Careless soldering can be a major cause of shorts on printed circuit boards (PCB). When soldering is done improperly or without proper attention to detail, it can lead to solder bridges or excessive solder on the PCB, causing unintended connections between different circuit tracks. These shorts can disrupt the flow of current and lead to malfunctioning or non-functional circuits. It is important to ensure proper soldering techniques and attention to detail to avoid these issues.

In a series circuit, the current is the same at every point in the circuit. This means that the current through one component is equal to the current through any other component in the circuit. Therefore, the total current in a series circuit is equal to the current through one component.

In a series-parallel circuit, the total current is the same throughout the circuit. Given that the series current is 6 amps, it means that the total current in the circuit is also 6 amps. Therefore, the correct answer is 6a.

A Field-Effect Transistor (FET) is a component that uses voltage to control the size of the current flow channel. FETs are three-terminal devices, where the voltage applied to the gate terminal determines the conductivity of the channel between the source and drain terminals. By varying the gate voltage, the FET can either allow or restrict the flow of current, making it an ideal component for voltage-controlled amplification and switching applications.

Capacitive reactance is the opposition that a capacitor exhibits to the flow of alternating current (AC). It is caused by the capacitor's ability to store and release electrical energy. When AC voltage is applied, the capacitor charges and discharges, creating a phase shift between the current and voltage. This opposition is measured in ohms and increases with frequency. Capacitive reactance is the correct answer because it specifically refers to the opposition of a capacitor to AC. Impedance, on the other hand, is a broader term that encompasses the total opposition to current flow in a circuit, including resistance and reactance.

The amount of resistance is a factor that determines the time required to charge a capacitor. Resistance limits the flow of current in the circuit, affecting the rate at which the capacitor charges. Higher resistance slows down the charging process, while lower resistance allows for faster charging. Therefore, the amount of resistance in the circuit directly influences the time it takes for the capacitor to charge.