2A652 CDC Pretest Volume 2

The magnetic field of an electromagnet can be varied by changing the type of core, the number of turns in the coil, and the amount of current through the coil. The type of core affects the magnetic permeability, which determines how easily the magnetic field can be established. Increasing the number of turns in the coil increases the strength of the magnetic field. Finally, increasing the amount of current flowing through the coil increases the strength of the magnetic field according to Ampere's Law. Therefore, all of these factors can individually or collectively affect the magnetic field of an electromagnet.

A relay is an electrically operated switch. It is a device that allows a small electrical current to control a larger one, by using an electromagnet to mechanically open or close a circuit. Relays are commonly used in electrical systems to control high-power devices, such as motors or lights, with a low-power signal. They provide a safe and efficient way to control the flow of electricity in a circuit.

In order to generate a voltage electromechanically, a conductor is required. A conductor is a material that allows the flow of electric current. When a conductor moves relative to a magnetic field, it induces a voltage in the conductor according to Faraday's law of electromagnetic induction. This voltage can be generated only if there is a complete circuit, which allows the flow of current from the conductor. Therefore, a conductor is necessary for the electromechanical generation of a voltage.

Resistance is used to control current flow in a circuit. It is a measure of how much a material or component opposes the flow of electric current. When resistance is increased, the current flow decreases, and when resistance is decreased, the current flow increases. This property allows resistance to be used to regulate the amount of current flowing through a circuit.

Residual magnetism refers to the magnetism that remains in a material even after the magnetizing force has been removed. This phenomenon occurs due to the alignment of magnetic domains within the material. When a magnetic material is magnetized, the magnetic domains align in a specific direction. Even after the external magnetizing force is removed, some of these domains remain aligned, resulting in residual magnetism. This residual magnetism can be observed in materials such as iron or steel, where the material retains a magnetic field even when not in the presence of an external magnetic field.

Current is the correct answer because it refers to the flow or drift of electrons through a conductor in the same direction at the same time. Conductivity refers to the ability of a material to conduct electricity, voltage refers to the electric potential difference between two points, and valance refers to the combining capacity of an element.

A magnetic field refers to the areas around a magnet where its influence can be felt. It is the region in which magnetic forces are exerted on other magnetic objects or charged particles. The concept of a magnetic field is fundamental in understanding the behavior of magnets and their interactions with other objects.

The systematic method is the best method of troubleshooting because it involves a logical and organized approach to problem-solving. It allows for a step-by-step analysis of the issue, ensuring that all possible causes are considered and evaluated. This method helps to eliminate guesswork and reduces the chances of missing important details. By following a systematic approach, troubleshooting becomes more efficient and effective, leading to faster and more accurate solutions.

The term "dielectric" is used to refer to insulators. Dielectrics are materials that do not conduct electricity easily and have high resistance to the flow of electric current. They are commonly used in electrical insulation to prevent the flow of electricity and to store electrical energy in capacitors. Unlike conductors, which allow the flow of electric charges, dielectrics act as insulators by blocking the movement of electrons. Therefore, the correct answer is insulators.

Voltage is the correct answer because it refers to the potential difference between two points in a circuit. This potential difference is responsible for exerting a force on free electrons, causing them to move and create an electric current. Conductivity refers to the ability of a material to conduct electricity, while current refers to the flow of electric charge. Valence, on the other hand, is a term used in chemistry to describe the combining capacity of an element.

Ohm's Law is the correct answer because it describes the relationship between voltage, current, and resistance in an electrical circuit. According to Ohm's Law, the current flowing through a conductor is directly proportional to the voltage applied across it and inversely proportional to the resistance of the conductor. This relationship is expressed mathematically as I = V/R, where I is the current, V is the voltage, and R is the resistance. Ohm's Law is a fundamental principle in electrical engineering and is used to calculate and analyze various aspects of electrical circuits.

A good conductor needs only 3 valence electrons. Valence electrons are the electrons in the outermost shell of an atom, and they determine the atom's reactivity and ability to form bonds. In the context of conductivity, materials with fewer valence electrons are typically better conductors because they have more loosely held electrons that can move freely and carry electric charge. Therefore, having only 3 valence electrons would make a material a good conductor.

When a diode is placed in reverse bias, it acts as a spike protector. In this configuration, the diode allows current to flow in the reverse direction only when a voltage spike occurs. This helps to protect the circuit from high voltage spikes that could potentially damage other components. By effectively blocking the spikes, the diode ensures that only the desired voltage levels pass through the circuit, providing protection against sudden voltage surges. Therefore, a diode in reverse bias is commonly used as a spike protector.

When a soldering iron tip becomes pitted or worn, it can lead to poor soldering performance. To fix this issue, the tip should be redressed using a flat, fine, single-cut file. However, after redressing, it is important to tin the tip. Tinning involves applying a thin layer of solder to the tip, which helps to improve heat transfer and prevent oxidation. Therefore, the correct answer is "tinned."

Mutual induction is the process by which a changing current in one coil induces a voltage in another coil. This occurs when the magnetic field generated by the changing current in the first coil passes through the second coil, causing a voltage to be induced in it. This phenomenon is commonly used in transformers and other electrical devices to transfer energy from one coil to another. Inductance refers to the ability of a coil to store energy in its magnetic field, while self-induction specifically refers to the voltage induced in a coil due to its own changing current. Therefore, the correct answer is mutual induction.

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 input voltage 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 step-up transformer, the secondary windings have more turns of wire compared to the primary windings. This is because the transformer is designed to increase the voltage from the input side to the output side. By having more turns in the secondary windings, the transformer can step up the voltage while maintaining the same power. Therefore, the correct answer is "More".

A reference designation index is a troubleshooting aid that is designed to aid you if you see an unfamiliar symbol. It provides a list of symbols and their corresponding meanings, allowing you to quickly identify and understand unfamiliar symbols that may be encountered during troubleshooting. This index helps technicians and engineers navigate through complex diagrams and schematics, ensuring that they can accurately interpret the symbols and effectively troubleshoot any issues that may arise.

Electrostatic sensitive devices are identified by being marked with the MIL-STD-129 symbol or caution marking. This marking indicates that the device is sensitive to electrostatic discharge and needs to be handled with caution to prevent damage. The MIL-STD-129 symbol or caution marking serves as a visual indicator for individuals working with these devices to take appropriate precautions, such as wearing grounding straps, using anti-static packaging, and ensuring proper grounding of workstations and equipment.

The first step in soldering a conductor is to remove the insulation. This is necessary because soldering requires direct contact between the conductor and the solder. Insulation, such as plastic or rubber coating, prevents this direct contact and hinders the flow of heat and electrical current. By removing the insulation, the conductor is exposed and ready for the soldering process.

Electromagnetic induction is the principle behind all electromechanical generation. This process involves the generation of an electric current in a conductor when it is exposed to a changing magnetic field. When a conductor moves through a magnetic field or when the magnetic field around a conductor changes, it induces a voltage in the conductor, resulting in the generation of electricity. This principle is fundamental to the functioning of generators, transformers, and other electromechanical devices used for power generation and transmission.

The commutator in a DC generator is responsible for converting the alternating current (AC) produced in the armature coils into direct current (DC). It achieves this by reversing the current flow in the armature coils at the appropriate time, ensuring that the output current from the generator flows in only one direction. This process of reversing the current direction allows the generator to produce a steady and continuous DC voltage, which is essential for powering devices that require a constant source of electrical energy.

A latching relay is a type of relay that requires a second coil to be energized in order for the contacts to return to their original positions. This means that once the relay is energized, it will remain in that state until the second coil is energized, which will then reset the contacts back to their original positions. This type of relay is commonly used in applications where it is necessary to maintain a specific state or position until a specific condition is met.

LEDs (Light Emitting Diodes) are semiconductor devices that emit light when an electric current is applied to them. The approximate operating voltage of an LED is typically around 1.6 volts. This voltage is necessary to overcome the forward voltage drop across the diode junction and allow current to flow through the LED, causing it to emit light. Different types of LEDs may have slightly different operating voltages, but 1.6 volts is a common approximation.

The Silicon Controlled Rectifier (SCR) has three PN junctions. The PN junctions are formed by the combination of P-type and N-type semiconductor materials. These junctions play a crucial role in the operation of the SCR, allowing it to control the flow of current in a circuit. The three junctions in the SCR are known as the anode-cathode junction, the anode-gate junction, and the cathode-gate junction. Each junction serves a specific purpose in regulating the SCR's conduction and blocking states.

Zones are a troubleshooting aid that is designed to aid you in finding components on a diagram. They divide a diagram into different areas or sections, making it easier to locate specific components or areas of interest. By using zones, you can quickly identify the location of components and navigate through the diagram more efficiently, which can be helpful in troubleshooting and identifying potential issues.

A heat sink is a device used in soldering to absorb and dissipate heat. When soldering, excessive heat can damage not only the component being soldered but also other nearby components in the circuit. By using a heat sink, the heat is directed away from the soldering point and spread out over a larger area, preventing it from causing damage to other components. Therefore, the correct answer is to prevent heat from damaging other components in the circuit.

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 reliable connection, ensuring good electrical conductivity and mechanical strength. The 180 degree wrap allows for maximum surface contact between the conductor and the terminal, reducing the risk of loose or weak connections.

The correct answer is "wire touches the bottom". This means that the wire is inserted into the solder cup until it reaches the bottom of the cup. This ensures a secure connection and proper contact between the wire and the cup, which is important for the effectiveness and reliability of the soldering process.

An atom with eight electrons in its outermost shell is said to be stable. This is because the outermost shell, also known as the valence shell, is considered to be complete when it contains eight electrons. This configuration is known as the octet rule, which states that atoms tend to gain, lose, or share electrons in order to achieve a stable configuration with eight electrons in the valence shell. Therefore, an atom with eight electrons in its outermost shell is considered stable.

Permeability refers to the ability of a material to allow lines of force to pass through it. It is a measure of how easily magnetic flux can pass through a substance. This property is important in determining the behavior of magnetic fields and is commonly used in the design and analysis of electromagnetic devices such as transformers and inductors.

In a capacitor, the dielectric is the insulator. A dielectric is a material that is placed between the two plates of a capacitor to increase its capacitance. It acts as an electrical insulator, preventing the flow of direct current between the plates while allowing the storage of electric charge. The dielectric material can be made of various substances, such as ceramic, plastic, or paper, which have high resistivity and low conductivity. By using a dielectric, the capacitance of the capacitor can be increased, allowing it to store more charge for a given voltage.

Atoms are made up of three types of particles: electrons, protons, and neutrons. Electrons have a negative charge and are located in the electron cloud surrounding the nucleus. Protons have a positive charge and are located in the nucleus. Neutrons have no charge and are also located in the nucleus. Therefore, the correct answer is electrons and protons, as both of these particles are present in every atom.

In a parallel circuit, the source current will be divided among the different branches based on their respective resistances. The branch with a lower resistance will allow more current to flow through it, while the branch with a higher resistance will have less current flowing through it. This is because the resistance determines how much the current is impeded in each branch. Therefore, the statement that the source current in a parallel circuit will be divided according to resistances is correct.

A capacitor stores energy in the form of an electrostatic field. When a voltage is applied across the capacitor, it creates an electric field between its plates. This electric field stores energy in the form of electrostatic potential energy. The energy is stored in the electric field until it is discharged or used in a circuit. Capacitors are commonly used in electronic devices to store and release electrical energy efficiently.

Capacitive reactance is the opposition of a capacitor to AC. It is a measure of how a capacitor resists the flow of alternating current. When an AC signal is applied to a capacitor, the capacitor charges and discharges, causing a phase shift between the voltage and current. This opposition to the flow of current is known as capacitive reactance. It is represented by the symbol Xc and is inversely proportional to the frequency of the AC signal and the capacitance of the capacitor. As the frequency increases, the capacitive reactance decreases, allowing more current to flow through the capacitor.

Biasing refers to the process of applying a specific voltage to a semiconductor device, such as a diode, in order to establish the desired operating conditions. By applying a bias voltage, the depletion region of the diode can be expanded or contracted, which affects its ability to conduct current. This allows for control over the diode's behavior and ensures that it operates within its desired range.

To turn off an SCR (Silicon Controlled Rectifier), the current flowing through it must drop below the holding current. The holding current is the minimum current required to keep the SCR in the on state. Once the current falls below this threshold, the SCR will turn off and stop conducting. This is because the SCR is a latching device that requires a specific level of current to maintain conduction.

The best method of repairing a lifted circuit track on a PCB is to replace it with insulated wire. This is because insulated wire provides proper electrical insulation and prevents any short circuits or interference. By replacing the lifted track with insulated wire, the circuit can be restored to its original functionality without any risk of further damage.

In a series circuit, the current remains the same throughout 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.

The anode of a diode is constructed of positive material because it is the terminal through which current flows into the diode. In a diode, current can only flow from the anode (positive terminal) to the cathode (negative terminal), making the anode positive with respect to the cathode. This construction allows the diode to function as a one-way valve for electric current, allowing current to flow in only one direction.

Once the avalanche point has been reached, a zener diode will start to conduct in reverse bias. This is because at the avalanche point, the electric field across the depletion region becomes strong enough to cause the generation of electron-hole pairs through the process of impact ionization. This leads to a rapid increase in the reverse current flowing through the diode, allowing it to conduct. Therefore, once the avalanche point is reached, the zener diode will conduct in reverse bias.

A transformer is an electrical device that can change the voltage of an alternating current (AC) while keeping the power constant. It works on the principle of electromagnetic induction. When the voltage is stepped up or stepped down, the current and resistance may change accordingly, but the power remains the same. Therefore, a transformer will change the current, voltage, and resistance, but it will not change the power.

An inductor is called a reactive device because it stores energy in its magnetic field and releases it back to the circuit when the current changes. Unlike a resistive device that dissipates energy in the form of heat, an inductor does not consume power but instead reacts to changes in current by storing or releasing energy. This reactive behavior is characteristic of inductors and distinguishes them from other types of devices.

During the analysis step of troubleshooting, you try to determine which system could cause the malfunction by carefully examining the symptoms and gathering information about the problem. This involves analyzing the behavior of the system, identifying any patterns or trends, and considering all possible factors that could contribute to the malfunction. By conducting a thorough analysis, you can narrow down the potential causes and focus your efforts on resolving the issue effectively.

Recognition is the troubleshooting step that is done by knowing proper equipment operation. This step involves identifying the symptoms and patterns of the issue based on the knowledge of how the equipment should function correctly. By recognizing the expected behavior of the equipment, it becomes easier to pinpoint any deviations or abnormalities, which can then guide further troubleshooting actions.

In a parallel circuit, the total voltage is equal to the voltage across each branch. This means that the voltage across each branch is the same and equal to the total voltage of the circuit. In a parallel circuit, the current splits up and flows through each branch independently, but the voltage across each branch remains constant. Therefore, the correct answer is "voltage across each branch".

The time required to charge a capacitor is determined by the amount of resistance in the circuit. Higher resistance will result in a slower charging time, while lower resistance will allow the capacitor to charge more quickly. This is because resistance limits the flow of current in the circuit, and the charging of a capacitor relies on the flow of current. Therefore, the amount of resistance plays a crucial role in determining the time it takes for a capacitor to charge.

An inductor is a passive electronic component that stores energy in the form of a magnetic field. When a current flows through an inductor, the magnetic field is created, and this magnetic field stores the energy. This stored energy can then be released back into the circuit when the current changes or stops flowing. Therefore, the correct answer is that an inductor stores energy in the form of a magnetic field.

The forward breakover voltage refers to the minimum voltage required to trigger the SCR and allow current flow through the device. It is the voltage level at which the SCR switches from its non-conducting state to its conducting state. This voltage is applied to the gate terminal of the SCR to initiate conduction. The forward breakover voltage is a critical parameter in SCR circuits as it determines the point at which the device starts conducting and allows current to flow.