1.
Concerning the flow of electricity, materials such as rubber, glass, and dry wood are known as
Correct Answer
B. Insulators
Explanation
Rubber, glass, and dry wood are known as insulators because they do not allow the flow of electricity through them. Insulators have high resistance and are used to prevent the flow of electric current, protecting people and equipment from electrical shocks. In contrast, conductors are materials that allow the flow of electricity, such as metals. Thermocouples are devices used to measure temperature, and electric cells are devices that convert chemical energy into electrical energy.
2.
Dry wood makes a good conductor.
Correct Answer
B. False
Explanation
Dry wood is actually a poor conductor of electricity. Conductors are materials that allow the flow of electric current, while insulators impede the flow. Dry wood falls under the category of insulators as it does not allow the easy movement of electric charges. It has high resistance to the flow of electricity and does not conduct electricity well.
3.
A ______ is the fundamental unit of a battery.
Correct Answer
C. Cell
Explanation
A cell is the fundamental unit of a battery. A battery consists of one or more cells, which convert chemical energy into electrical energy. Each cell contains a positive electrode (cathode), a negative electrode (anode), and an electrolyte that allows the movement of ions between the electrodes. When a circuit is connected to a battery, a chemical reaction occurs within the cell, generating an electric current. Therefore, a cell is the basic building block of a battery, making it the correct answer.
4.
Ohm's law may be expressed as an equation I=E/R, where "E" represents:
Correct Answer
B. Voltage in volts
Explanation
The correct answer is "Voltage in volts" because Ohm's law states that the current flowing through a conductor is directly proportional to the voltage across the conductor and inversely proportional to the resistance of the conductor. In the equation I=E/R, "E" represents the voltage, which is measured in volts.
5.
Ohm's law may be expressed as an equation I=E/R, where "R" represents:
Correct Answer
A. Resistance in ohms.
Explanation
The equation I=E/R is known as Ohm's law, which relates current (I) to voltage (E) and resistance (R). In this equation, "R" represents resistance in ohms. This means that resistance is the quantity that is being measured in ohms in the context of Ohm's law.
6.
When the voltage is doubled, power is
Correct Answer
D. Doubled twice
Explanation
When the voltage is doubled, the power is directly proportional to the square of the voltage. Therefore, if the voltage is doubled twice, the power will be doubled twice, resulting in a four-fold increase in power.
7.
The study of electricity began with the ancient___________
Correct Answer
C. Greeks
Explanation
The study of electricity began with the ancient Greeks. They were the first to observe certain electrical phenomena, such as static electricity, and they also developed theories about the nature of electricity. The Greek philosopher Thales of Miletus is often credited as one of the first to study electricity, as he discovered that rubbing amber could attract lightweight objects. This initial exploration by the Greeks laid the foundation for further advancements in the understanding and application of electricity throughout history.
8.
Charged atoms are called_________
Correct Answer
D. Ions
Explanation
Charged atoms are called ions because they have gained or lost electrons, resulting in a net positive or negative charge. This charge imbalance makes them electrically active and capable of participating in chemical reactions and electrical conductivity. Ions play a crucial role in various biological and physical processes, such as nerve transmission and electrolyte balance in the body.
9.
The flow of electrical energy through a conductor is called
Correct Answer
B. Electric current, or electricity.
Explanation
The flow of electrical energy through a conductor is referred to as electric current or electricity. This refers to the movement of electric charges, such as electrons, along the conductor. The term "electric current" is commonly used to describe this flow of electrical energy.
10.
Material that permits the free movement of a large number of electrons, such as copper wire, is known as a good
Correct Answer
A. Conductor of electricity.
Explanation
A material that allows the easy flow of a large number of electrons is called a good conductor of electricity. Copper wire is specifically mentioned as an example of such a material. This means that copper wire allows the movement of electric charges through it with minimal resistance, making it an efficient conductor of electricity.
11.
N order, the best conductors of electricity are
Correct Answer
D. Silver, copper, and aluminum wire.
Explanation
The best conductors of electricity are materials that allow electric current to flow easily through them. Silver is the best conductor among commonly used materials, followed by copper and then aluminum. Therefore, the correct order of the best conductors of electricity is silver, copper, and aluminum wire.
12.
Electromotive force may be produced by
Correct Answer
D. All of the answers are correct.
Explanation
The correct answer is that all of the answers are correct because electromotive force can be produced by friction and pressure, heat and light, chemical action, and magnetism. These different sources can generate a potential difference and create an electric current. Therefore, all of the given options are valid explanations for the production of electromotive force.
13.
The true cause of electricity was found with the development of
Correct Answer
B. Atomic theory of matter.
Explanation
The true cause of electricity was found with the development of the atomic theory of matter. This theory explains that electricity is caused by the movement of charged particles, such as electrons, within atoms. It provided a scientific understanding of how electricity is generated and how it behaves, leading to advancements in the field of electrical engineering and the development of various electrical devices.
14.
A substance that has few free electrons is called
Correct Answer
B. An insulator.
Explanation
An insulator is a substance that has few free electrons. Unlike conductors, which have many free electrons that can easily move through the material, insulators have tightly bound electrons that do not flow easily. This lack of free electrons makes insulators poor conductors of electricity. Therefore, the correct answer is "An insulator."
15.
A common name for the voltage produced by rubbing two materials together is
Correct Answer
A. Static electricity.
Explanation
The correct answer is Static electricity because when two materials are rubbed together, it creates an imbalance of electric charges on their surfaces. This imbalance results in the buildup of static electricity, which can cause objects to attract or repel each other. Dry charge, friction, and dynamic charge are not common names for the voltage produced by rubbing two materials together.
16.
Wires in an electric circuit are designed to keep
Correct Answer
C. electrical resistance low.
Explanation
The correct answer is "electrical resistance low." Wires in an electric circuit are designed to have low resistance in order to allow the flow of electrical current with minimal obstruction. High resistance would impede the flow of current and cause energy loss in the form of heat. Therefore, wires are designed to minimize resistance and ensure efficient transmission of electricity.
17.
A significant feature of a battery composed of secondary cells such as an automobile battery is that it is
Correct Answer
C. Rechargeable.
Explanation
The correct answer is "Rechargeable" because secondary cells, such as those found in an automobile battery, have the ability to be recharged and used multiple times. This is in contrast to primary cells, which are disposable and cannot be recharged.
18.
The direction of electron movement in any conductor is
Correct Answer
A. From negative potential to positive potential.
Explanation
In any conductor, electrons move from an area of higher negative potential to an area of lower negative potential. This is because electrons are negatively charged particles and are attracted to positive charges. Therefore, they flow towards the positive potential, which is the opposite direction of conventional current flow.
19.
Which of the following kinds of waves can be felt by human beings?
Correct Answer
A. Vibrations
Explanation
Vibrations can be felt by human beings. When an object vibrates, it creates waves that can be perceived by our sense of touch. These waves are transmitted through the air or a medium and can cause the human body to physically feel the vibrations. On the other hand, radio waves, radar waves, and light waves cannot be felt by human beings as they are not directly detectable by our sense of touch.
20.
The ___________ is the length of a cycle expressed in distance units.
Correct Answer
C. Wave length
Explanation
The wavelength is the length of a cycle expressed in distance units. In other words, it refers to the distance between two consecutive points in a wave that are in phase with each other. It is usually represented by the symbol λ (lambda) and is commonly used to describe characteristics of electromagnetic waves and other types of waves.
21.
The __________ is the number of cycles repeated during one second of time.
Correct Answer
A. Frequency
Explanation
Frequency is the correct answer because it refers to the number of cycles repeated during one second of time. It is a measure of how often an event or phenomenon occurs in a given period. In the context of the question, frequency represents the rate at which cycles occur within a specific time frame. Amplitude refers to the magnitude or intensity of a wave, speed refers to the rate at which an object moves, and cycle is a general term that does not specifically measure the number of repetitions in a given time period.
22.
The __________ is the wave strength at particular points along with the wave.
Correct Answer
B. Amplitude
Explanation
The amplitude of a wave refers to the maximum displacement of a particle from its equilibrium position. It represents the wave's strength or intensity at specific points along the wave. A higher amplitude indicates a stronger wave, while a lower amplitude indicates a weaker wave. Therefore, the amplitude is the correct answer as it accurately describes the wave's strength at particular points.
23.
________occurs when there is a change in the density or atmosphere in which the wave is
Correct Answer
C. Refraction
Explanation
Refraction occurs when there is a change in the density or atmosphere in which the wave is traveling. This causes the wave to change direction and bend as it passes from one medium to another.
24.
_________ causes the spreading of radio waves behind obstructions.
Correct Answer
B. Diffraction
Explanation
Diffraction causes the spreading of radio waves behind obstructions. Diffraction occurs when waves encounter an obstacle or pass through a narrow opening, causing them to bend and spread out. In the case of radio waves, when they encounter obstructions such as buildings or mountains, they diffract around them, allowing the waves to reach areas that would otherwise be blocked. This phenomenon is essential in radio communication as it enables signals to propagate and reach receivers even in the presence of obstacles.
25.
_________ causes the spreading of radio waves behind obstructions.
Correct Answer
B. Diffraction
Explanation
Diffraction causes the spreading of radio waves behind obstructions. When radio waves encounter an obstacle, such as a building or a mountain, they bend around it and spread outwards. This phenomenon is known as diffraction. Unlike reflection, which involves bouncing off the obstacle, diffraction allows the radio waves to continue propagating, albeit in a slightly altered direction. Refraction refers to the bending of waves when passing through different mediums, while trapping is not a relevant concept in this context.
26.
______ occurs when a temperature inversion in the atmosphere holds cold air close to the Earth's surface.
Correct Answer
A. Trapping
Explanation
Trapping occurs when a temperature inversion in the atmosphere holds cold air close to the Earth's surface. This phenomenon prevents the warm air from rising and mixing with the colder air above, creating a layer of stagnant, trapped air near the surface. This can lead to the buildup of pollutants and other particulate matter, causing poor air quality and potential health hazards.
27.
The following are all Navy radar general categories except:
Correct Answer
B. Rescue
Explanation
The question asks for the category that is not a general category of Navy radar. The categories listed are Search, Rescue, Fire Control, and Special. Search, Fire Control, and Special are all general categories of Navy radar. However, Rescue is not a general category of Navy radar.
28.
The information gathered by most shipboard radar is presented and analyzed in a shipboard space called the
Correct Answer
A. Combat Information Center.
Explanation
The correct answer is Combat Information Center. This is where the information gathered by shipboard radar is presented and analyzed. It serves as a central hub for monitoring and controlling the ship's combat operations, including radar data interpretation and decision-making processes. The Combat Information Center is responsible for maintaining situational awareness, coordinating responses, and ensuring effective communication during combat situations.
29.
Radar can be used to track both friendly and potentially threatening
Correct Answer
B. Aircraft
Explanation
Radar technology is capable of tracking both friendly and potentially threatening aircraft. Radar systems use radio waves to detect and locate objects in the air, including aircraft. By emitting radio waves and analyzing the reflected signals, radar can determine the position, speed, and direction of aircraft. This information is crucial for air traffic control, military operations, and monitoring airspace. Therefore, radar is a suitable technology for tracking aircraft, whether they are friendly or potentially threatening.
30.
Radio waves are ______ from the ionosphere, which is generally 30-250 miles above the Earth.
Correct Answer
B. Reflected
Explanation
Radio waves are reflected from the ionosphere, which is generally 30-250 miles above the Earth.
31.
What is the basic continuous wave of a modulated wave called?
Correct Answer
A. Carrier Wave
Explanation
The basic continuous wave of a modulated wave is called the carrier wave. This wave carries the information being transmitted and is modulated by adding or altering its characteristics to encode the desired data. The carrier wave itself does not carry any information, but it serves as a medium for transmitting the modulated signal.
32.
What is one complete sequence of the strength of a wave as it passes through a point in space?
Correct Answer
A. Cycle
Explanation
The strength of a wave as it passes through a point in space can be described by its cycle. A cycle refers to one complete oscillation of a wave, from its starting point to its highest point, then to its lowest point, and back to its starting point. It represents the complete pattern of the wave's amplitude and can be used to measure the strength or intensity of the wave at a specific point in space.
33.
Electronics is the basic study of _______________.
Correct Answer
A. Electromagnetic waves
Explanation
Electronics is the basic study of electromagnetic waves because it involves the understanding and manipulation of the behavior and properties of these waves to design and develop electronic devices and systems. This includes topics such as electromagnetism, signal processing, communication systems, and the principles of electronic circuits and components. By studying electromagnetic waves, engineers and scientists can harness their properties to create various technologies like radios, televisions, computers, and mobile devices.
34.
The term RADAR stands for __________________.
Correct Answer
A. Radio detection and ranging
Explanation
The term RADAR stands for Radio detection and ranging. This acronym accurately describes the technology used in RADAR systems, which involves the detection and measurement of objects using radio waves. By emitting radio waves and analyzing the reflected signals, RADAR systems can determine the distance, direction, and speed of objects in their vicinity.
35.
Frequency modulation is abbreviated as _______________.
Correct Answer
A. FM
Explanation
Frequency modulation is abbreviated as FM. FM is a method of encoding information on a carrier wave by varying the frequency of the wave. It is commonly used in radio broadcasting to transmit audio signals. By modulating the frequency of the carrier wave, FM allows for a higher quality and more reliable transmission of audio signals compared to amplitude modulation (AM). Therefore, FM is the correct abbreviation for frequency modulation.
36.
Amplitude modulation is abbreviated as __________
Correct Answer
B. AM
Explanation
Amplitude Modulation (AM) is a method of transmitting information by varying the amplitude of a carrier wave in accordance with the message signal. It is commonly used in radio broadcasting to transmit audio signals. PM stands for Phase Modulation, DW and FR are not commonly used abbreviations in the context of modulation. Therefore, the correct answer for the abbreviation of Amplitude Modulation is AM.
37.
_____________ uses highly sophisticated electronics to counter enemy electromagnetic waves.
Correct Answer
A. Electronic Warfare
Explanation
Electronic Warfare uses highly sophisticated electronics to counter enemy electromagnetic waves. It involves the use of electronic systems to detect, deceive, and disrupt enemy radar, communication, and other electronic systems. This allows military forces to gain a tactical advantage by denying the enemy the use of their electronic capabilities. Anti Submarine Warfare, Electronics, and Electricity do not specifically refer to the use of sophisticated electronics to counter enemy electromagnetic waves, making them incorrect answers.
38.
What type of waves can travel through a complete vacuum?
Correct Answer
D. Electromagnetic Waves
Explanation
Electromagnetic waves can travel through a complete vacuum because they do not require a medium to propagate. Unlike sound waves, which require a medium such as air or water, electromagnetic waves can travel through empty space, making them the only type of wave that can do so. Vibrations and water waves, on the other hand, require a medium to transmit their energy and cannot travel through a vacuum.
39.
What does every electronic device use for basic operation?
Correct Answer
B. Electromagnetic waves
Explanation
Every electronic device uses electromagnetic waves for basic operation. Electromagnetic waves are a form of energy that can travel through space or matter. They are used in various electronic devices for communication, transmission of data, and powering the device itself. These waves can carry information in the form of signals and are essential for the functioning of devices such as radios, televisions, smartphones, and computers.
40.
How is frequency (Hertz) abbreviated?
Correct Answer
B. Hz
Explanation
The correct abbreviation for frequency in Hertz is "Hz".