Electrical Principles And Technology Unit Review
A unt review for this unit including: Calculating Power, Watts, Resistance, Current, Efficiency etc., Static Electricity, Electrical Safety, Current Electricity, Cells & Batteries, Electrical Circuits (ie. Flashlight), Resistance, Energy Transformation/ Forms, Motors (ie. St Louis Motor, Magnetism) and Electricity Generators.
Good Luck :)
Questions and Answers
- 1.
These types of conductors have no resistance to electron flow, which is why they are known to be perfect conductors. They are called _______.
- A.
Superconductors
- B.
Metallic conductors
- C.
Resistance-less conductors
- D.
Magnetic conductors
Correct Answer
A. SuperconductorsExplanation
Superconductors are conductors that have zero electrical resistance, allowing electrons to flow through them without any hindrance. This unique property makes them perfect conductors. Unlike metallic conductors, which still have some resistance, superconductors exhibit no resistance at all. The term "resistance-less conductors" accurately describes superconductors as they lack any resistance to electron flow. Magnetic conductors, on the other hand, refer to materials that can conduct or interact with magnetic fields, but this term does not capture the zero resistance characteristic of superconductors.Rate this question:
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- 2.
The more charged particles in a solution _________.
- A.
The more voltage it produces
- B.
The more resistance there is
- C.
The less resistance there is
- D.
The less voltage is produced
Correct Answer
C. The less resistance there isExplanation
When there are more charged particles in a solution, it means that there are more ions available to carry electric current. This leads to a decrease in resistance, as the ions can move more easily through the solution. As a result, the solution will have less resistance, allowing for a greater flow of electric current.Rate this question:
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- 3.
_______ is the direction of a magnetic or electric field.
Correct Answer
Polarity
polarityExplanation
The term "polarity" refers to the direction of a magnetic or electric field. It is used to describe the orientation or alignment of the field lines, indicating the positive and negative ends or poles. In the context of magnets, polarity determines how the north and south poles are arranged. In the case of electric fields, polarity indicates the direction of the flow of electric charge.Rate this question:
- 4.
The _____ (one or two words) in an electric motor attracts the armature to create motion; in which, creates electricity.
Correct Answer
Permanent magnets
permanent magnets
Permanent Magnets
magnet
Magnet
permanent magnet
Permanent magnet
magnets
MagnetsExplanation
The correct answer is "permanent magnets". In an electric motor, the permanent magnets attract the armature, which creates motion. This motion then generates electricity.Rate this question:
- 5.
Determine if this statment true or false: A generator stores energy.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
A generator does not store energy. Instead, it converts mechanical energy into electrical energy. It uses a fuel source, such as gasoline or diesel, to power an engine that rotates a magnet within a coil of wire, producing an electrical current. However, the generator itself does not have the capability to store energy for later use.Rate this question:
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- 6.
The movement of charges from an object to another without further movement is called __________.
Correct Answer
Static Electricity
Static electricity
static electricityExplanation
The movement of charges from one object to another without further movement is known as static electricity. This phenomenon occurs when there is an imbalance of positive and negative charges on objects, causing them to attract or repel each other. Static electricity is commonly experienced through activities such as rubbing two objects together or walking on a carpet and then touching a metal object, resulting in a small electric shock.Rate this question:
- 7.
An example of a static electrical charge is _______.
- A.
Lightning
- B.
Batteries
- C.
Current
- D.
Ohms
Correct Answer
A. LightningExplanation
An example of a static electrical charge is lightning. Lightning is a natural phenomenon that occurs when there is a buildup of static electricity in the atmosphere. It is a sudden discharge of electrical energy that can occur between clouds, from a cloud to the ground, or between different parts of the same cloud. This discharge creates a bright flash of light and a loud thunderclap. Unlike other options like batteries, current, or ohms, which are related to electrical energy in different ways, lightning specifically represents a static electrical charge due to its sudden and powerful nature.Rate this question:
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- 8.
Why do objects attract to one another?
- A.
Opposite charges
- B.
Similar charges
- C.
Neutrons
- D.
Electrons
Correct Answer
A. Opposite chargesExplanation
Objects attract to one another due to opposite charges. Opposite charges create an electric field around them, and when two objects with opposite charges come close to each other, they experience a force of attraction. This force is known as the electrostatic force and is responsible for objects sticking together or attracting to each other.Rate this question:
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- 9.
How does spraying water on laundry help reduce static cling?
- A.
The water absorbs electrical charge
- B.
The water contains protons
- C.
Water is a magnet
- D.
The charges leave onto a different object with opposite charges
Correct Answer
A. The water absorbs electrical chargeExplanation
Water is a polar molecule, meaning it has a positive and a negative end. When water is sprayed on laundry, it can absorb electrical charge because the positive and negative ends of the water molecules attract and neutralize the static charge present on the laundry. This helps to reduce static cling as the charges are no longer present to cause the clothes to stick together.Rate this question:
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- 10.
When electrons discharge, they go into the ground via a _________ wire.
Correct Answer
Ground
groundExplanation
When electrons discharge, they go into the ground via a ground wire. The ground wire provides a path of least resistance for the electrons to flow into the ground, preventing any build-up of excess electrical charge. This helps to protect electrical equipment and prevent electrical shocks or damage. The term "ground" refers to the Earth, which serves as a large reservoir of charge that can absorb and dissipate the excess electrons.Rate this question:
- 11.
A ________ is designed to interrupt the power to a circuit when the current flow exceeds safe levels.
Correct Answer
fuse
FuseExplanation
A fuse is a safety device that is designed to interrupt the power to a circuit when the current flow exceeds safe levels. When the current exceeds the rated value of the fuse, it causes the fuse to melt and break the circuit, preventing any further flow of electricity. This helps to protect the circuit and the connected devices from damage or overheating caused by excessive current flow.Rate this question:
- 12.
A _________ occurs when there is a low resistance connection between two conductors supplying electrical power to any circuit.
- A.
Short circuit
- B.
Malfunction
- C.
Electrical shock
- D.
Spark
Correct Answer
A. Short circuitExplanation
A short circuit occurs when there is a low resistance connection between two conductors supplying electrical power to any circuit. This connection bypasses the normal load, causing a sudden surge of current. This can lead to overheating, damage to the circuit, and potentially a fire hazard.Rate this question:
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- 13.
____________ is the energy carried by charged particles.
Correct Answer
Electrical energy
Electrical Energy
electrical energyExplanation
The correct answer is electrical energy. Electrical energy refers to the energy that is carried by charged particles, such as electrons. It is the energy associated with the movement of these charged particles through a conductor, such as a wire, and is commonly used to power electrical devices and systems. The term "electrical energy" can be written in various forms, including capitalized or lowercase letters, but the meaning remains the same.Rate this question:
- 14.
How much current is created when a 30 V battery creates a current through a 15 Ω resistor?
Correct Answer
2 A
2A
2 amperes
2 amps
2 Amperes
2 AmpsExplanation
The current created when a 30 V battery creates a current through a 15 Ω resistor is 2 A (amperes) or 2 Amps. This can be determined using Ohm's Law, which states that the current (I) flowing through a conductor is equal to the voltage (V) across the conductor divided by the resistance (R) of the conductor. In this case, the voltage is 30 V and the resistance is 15 Ω, therefore the current is 30 V / 15 Ω = 2 A.Rate this question:
- 15.
The measurement used to measure voltage is ________.
Correct Answer
V
volts
VoltsExplanation
The measurement used to measure voltage is represented by the letter "V" and is commonly referred to as "volts".Rate this question:
- 16.
The measurement used to measure current is _______.
Correct Answer
Amps
amps
amperes
Amperes
AExplanation
The measurement used to measure current is amps or amperes. The symbol for ampere is A.Rate this question:
- 17.
The process of which you use a small battery to split molecules into their elements is called _________.
- A.
Electrolysis
- B.
Hydro-plating
- C.
Hydrolysis
- D.
Energy transformation
Correct Answer
A. ElectrolysisExplanation
Electrolysis is the process in which a small battery is used to split molecules into their elements. This process involves the use of an electric current to drive a non-spontaneous chemical reaction, causing the decomposition of compounds into their constituent elements. Hydro-plating and hydrolysis are not related to the splitting of molecules using a small battery, while energy transformation is a broader concept that does not specifically refer to this particular process.Rate this question:
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- 18.
A _________, is a paste or liquid that conducts electricity because it contains chemicals that form ions.
- A.
Electrolyte
- B.
Battery
- C.
Dry cell
- D.
Wet cell
Correct Answer
A. ElectrolyteExplanation
An electrolyte is a substance, either in paste or liquid form, that can conduct electricity due to the presence of chemicals that form ions. These ions are responsible for carrying the electric charge through the solution. In the context of the given question, an electrolyte is the correct answer as it accurately describes the substance that conducts electricity in a battery or cell.Rate this question:
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- 19.
Who had made the first practical battery by piling copper and zinc disks on top of each other, and then seperating them with electrolyte-soaked paper discs.
- A.
Alessandro Volta
- B.
Faraday
- C.
Van de Graff
- D.
Ohm
Correct Answer
A. Alessandro VoltaExplanation
Alessandro Volta is credited with making the first practical battery by piling copper and zinc disks on top of each other and separating them with electrolyte-soaked paper discs. His invention, known as the Voltaic Pile, was an early form of battery that produced a continuous flow of electricity. Volta's groundbreaking work laid the foundation for the development of modern batteries and greatly contributed to the field of electrochemistry.Rate this question:
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- 20.
A dry cell is different from a wet cell because it is ____________.
- A.
Rechargeable
- B.
Non-rechargeable
- C.
Wet
- D.
Less resistance
Correct Answer
B. Non-rechargeableExplanation
A dry cell is different from a wet cell because it is non-rechargeable. Unlike a wet cell, which can be recharged by replenishing the electrolyte, a dry cell cannot be recharged. It contains a paste or gel electrolyte, which makes it more portable and less prone to leakage. Dry cells are commonly used in household batteries, such as AA or AAA batteries, while wet cells are typically found in car batteries or larger industrial applications.Rate this question:
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- 21.
The longer the wire is, the ______ its resistance.
- A.
Lower
- B.
Greater
- C.
Wider
- D.
Thinner
Correct Answer
B. GreaterExplanation
The longer the wire is, the greater its resistance. This is because resistance is directly proportional to the length of the wire. As the wire becomes longer, there is an increase in the number of atoms or ions that the electrons have to pass through, resulting in more collisions and hindrance to the flow of current. Therefore, the resistance of the wire increases.Rate this question:
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- 22.
The thicker the wire is, the ________ its resistance.
- A.
Lower
- B.
Greater
Correct Answer
A. LowerExplanation
The thicker the wire is, the lower its resistance. This is because a thicker wire provides more space for the flow of electrons, reducing the chances of collisions between the electrons and the wire's atoms. As a result, the resistance to the flow of electric current decreases, leading to a lower resistance value.Rate this question:
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- 23.
The ______ a wire is, the lower the resistance.
- A.
Cooler
- B.
Hotter
- C.
Less conductive
Correct Answer
A. CoolerExplanation
The lower the temperature of a wire, the lower its resistance. This is because at lower temperatures, the atoms in the wire vibrate less, causing less obstruction to the flow of electrons. As a result, the electrons can move more freely through the wire, leading to lower resistance. Conversely, at higher temperatures, the atoms vibrate more vigorously, creating more obstacles for the electrons and increasing resistance. Therefore, the correct answer is "cooler".Rate this question:
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- 24.
A _________ is a continuos resistor used to regulate electric current, it is also used to change the current flow.
- A.
Rheostat
- B.
Voltmeter
- C.
Ammeter
- D.
Battery
Correct Answer
A. RheostatExplanation
A rheostat is a type of resistor that is used to regulate electric current. It is also used to change the current flow. Unlike other options such as voltmeter, ammeter, and battery, a rheostat specifically serves the purpose of controlling and adjusting the flow of electric current.Rate this question:
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- 25.
What is the total resistance of a parallel circuit with two 20-ohm resistors and a 10-ohm resistor?
Correct Answer
5
5 Ohms
5 ohms
five
five ohms
Five ohms
Five OhmsExplanation
The total resistance of a parallel circuit is calculated using the formula 1/Rt = 1/R1 + 1/R2 + 1/R3 + ... In this case, the two 20-ohm resistors and the 10-ohm resistor are connected in parallel, so the formula becomes 1/Rt = 1/20 + 1/20 + 1/10. Simplifying this equation gives 1/Rt = 1/20 + 1/20 + 2/20, which further simplifies to 1/Rt = 4/20. Inverting both sides of the equation gives Rt = 20/4, which equals 5 ohms.Rate this question:
- 26.
What is an advantage of stringing lamps in a series circuit?
- A.
Requires less energy
- B.
Requires more energy
- C.
Less resistance
- D.
Greater resistance
Correct Answer
A. Requires less energyExplanation
Stringing lamps in a series circuit requires less energy because in a series circuit, the current is the same through each component. Therefore, when lamps are connected in series, the total voltage is divided equally among them. This means that each lamp receives a lower voltage compared to when it is connected individually. Since the power consumed by a device is directly proportional to the voltage applied to it, stringing lamps in a series circuit reduces the energy consumption of each lamp.Rate this question:
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- 27.
What is an disadvantage of stringing lamps in a series circuit?
- A.
If one lamp goes out, they all burn out as well
- B.
Requires more energy
- C.
Has more resistance
- D.
Has less current
Correct Answer
A. If one lamp goes out, they all burn out as wellExplanation
In a series circuit, the lamps are connected in a chain, so the same current flows through each lamp. If one lamp goes out, it breaks the circuit and interrupts the flow of current, causing all the lamps to go out. This is a disadvantage because it means that the failure of one lamp can result in the failure of all the lamps in the circuit.Rate this question:
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- 28.
What is an advantage of stringing lamps in a parallel circuit?
- A.
One lamp failure will not affect the other lamps
- B.
Requires less energy
- C.
Has less resistance
- D.
Has more voltage
Correct Answer
A. One lamp failure will not affect the other lampsExplanation
When lamps are strung in a parallel circuit, each lamp has its own separate pathway for the flow of electric current. This means that if one lamp fails, the other lamps will still receive the necessary current to continue functioning. Therefore, one lamp failure will not affect the other lamps in a parallel circuit.Rate this question:
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- 29.
What is an disadvantage of stringing lamps in a parallel circuit?
- A.
Requires more energy
- B.
Has more resistance
- C.
One lamp burns out they all do as well
- D.
Lights become dimmer when lamps are added
Correct Answer
A. Requires more energyExplanation
Stringing lamps in a parallel circuit does not require more energy. In fact, it is the opposite. In a parallel circuit, each lamp receives the same voltage, so the total energy consumed by the lamps is divided among them. This means that each lamp will receive the same amount of energy regardless of the number of lamps in the circuit. Therefore, the statement that stringing lamps in a parallel circuit requires more energy is incorrect.Rate this question:
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- 30.
The process of __________ is when you coat a surface of a conducting material with metal.
- A.
Electroplating
- B.
Electrolysis
- C.
Potential difference
- D.
Metal coating
Correct Answer
A. ElectroplatingExplanation
Electroplating is the process of coating a surface of a conducting material with metal. It involves the use of an electric current to deposit a thin layer of metal onto the surface of an object. This process is commonly used to enhance the appearance of objects, provide corrosion resistance, improve conductivity, and increase durability. Electrolysis refers to the decomposition of a compound using an electric current, potential difference is the voltage between two points in an electric circuit, and metal coating is a general term that can refer to various methods of applying a layer of metal onto a surface.Rate this question:
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- 31.
A DC generator is a device that converts mechanical energy into electrical energy using current which ________.
- A.
Flows in one direction
- B.
Changes direction
- C.
Has lots of electrons
- D.
Uses a lot of voltage
Correct Answer
A. Flows in one directionExplanation
A DC generator is designed to convert mechanical energy into electrical energy by producing a current that flows in one direction. This is achieved through the use of a commutator, which ensures that the current generated by the generator always flows in the same direction. By maintaining a constant flow of current in one direction, the DC generator is able to produce a steady and consistent output of electrical energy.Rate this question:
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- 32.
A AC generator is a device that converts mechanical energy into electrical energy using current which ________.
- A.
Flows in one direction
- B.
Changes direction
- C.
Has lots of electrons
- D.
Uses a lot of voltage
Correct Answer
B. Changes directionExplanation
An AC generator is a device that converts mechanical energy into electrical energy by producing an alternating current. The alternating current periodically changes its direction, flowing first in one direction and then in the opposite direction. This alternating current is essential for the efficient transmission of electrical energy over long distances and for powering various electrical devices.Rate this question:
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- 33.
A toaster is an example of this energy transformation:
- A.
Electrical to thermal
- B.
Thermal to electrical
- C.
Electrical to mechanical
- D.
Chemical to thermal
Correct Answer
A. Electrical to thermalExplanation
A toaster is an example of electrical to thermal energy transformation because it converts electrical energy into heat energy to toast bread.Rate this question:
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- 34.
A __________ is a device that converts thermal energy into electrical energy. Consisting of two different metals joined together to conduct heat.
- A.
Thermocouple
- B.
Motor
- C.
Transformer
- D.
Solar panel
Correct Answer
A. ThermocoupleExplanation
A thermocouple is a device that converts thermal energy into electrical energy. It is made up of two different metals that are joined together to conduct heat. When there is a temperature difference between the two junctions of the thermocouple, it creates a voltage difference, which can be used to generate electricity. This process is known as the Seebeck effect. Therefore, a thermocouple is the correct answer for a device that converts thermal energy into electrical energy.Rate this question:
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- 35.
You can make a ________ by winding current-carrying wire into a coil around a iron core.
- A.
Electromagnet
- B.
Motor
- C.
Circuit
- D.
Ground wire
Correct Answer
A. ElectromagnetExplanation
An electromagnet can be made by winding a current-carrying wire into a coil around an iron core. When an electric current flows through the wire, it creates a magnetic field around the coil. The iron core enhances the strength of the magnetic field. This electromagnet can be used in various applications such as lifting heavy objects, generating power in electric motors, and controlling switches in circuits.Rate this question:
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- 36.
What is power measured in?
Correct Answer
Watts
watts
WExplanation
Power is measured in watts (W). Watts is the standard unit used to quantify the rate at which work is done or energy is transferred. It represents the amount of energy consumed or produced per unit of time. The lowercase "watts" and the abbreviation "W" both refer to the same unit of measurement.Rate this question:
- 37.
A hair dryer has a power rating of 1000 W. It is plugged into a 120V outlet. What is the current flowing through the hair dryer? (Round to the nearest tenth)
Correct Answer
8.3 A
8.3AExplanation
The current flowing through the hair dryer can be calculated using Ohm's Law, which states that current (I) is equal to power (P) divided by voltage (V). In this case, the power rating of the hair dryer is 1000 W and the voltage is 120V. Therefore, the current flowing through the hair dryer is 1000/120 = 8.3 A.Rate this question:
- 38.
A microwave has a power rating of 800 W. If you cook a roast chicken in the microwave for 30 minutes on high, how many jules of energy are converted into heat by the microwave?
Correct Answer
1440000 J
1440000 J
1.4 MJ
1 440 000 JExplanation
The power rating of the microwave is given as 800 W. Power is defined as the rate at which energy is transferred or converted. Since the microwave operates for 30 minutes, we need to calculate the total energy converted. Using the formula: Energy = Power x Time, we can calculate the energy as 800 W x 30 minutes = 24,000 W-minutes. Since 1 J = 1 W-min, we can convert the energy to joules by multiplying by 60 (to convert minutes to seconds) to get 1,440,000 J. Therefore, the correct answer is 1440000 J. The other options are just different representations of the same value.Rate this question:
- 39.
An ordinary light bulb: 100 J of energy comes into a light bulb 5 J are used for light 95 J are released as heat What is the efficency of the light bulb?
Correct Answer
5 %
5%
5 percent
5 Percent
five percent
Five percent
Five PercentExplanation
The efficiency of the light bulb is 5%. This means that out of the 100 J of energy that comes into the light bulb, only 5 J are used for light, while the remaining 95 J are released as heat. The efficiency is calculated by dividing the useful output energy (5 J) by the total input energy (100 J) and multiplying by 100 to get a percentage. In this case, (5 J / 100 J) * 100 = 5%.Rate this question:
- 40.
Calculate the efficiency of an 1000 W kettle that takes 4 minutes to boil water. To heat the water to boiling point, it takes 196,000 J of energy. What is the efficiency of the kettle (round to nearest ones place ie. 12.4%= 12%)?
Correct Answer
82 %
82%
82 percent
82 Percent
Eighty two percent
eighty two percentExplanation
Here are the calculations to figuring out the efficiency of the kettle:
E1 = Power x Time
E= 196, 000 J
E2= Power x Time
E= (1000 W) x (4 min= 240 seconds)
E= (1000 W) x (240 sec.)
E= 240, 000 J
Percent Efficiency= Joules of useful energy / joules of input energy
Efficiency= 196000/ 240000
E= 0.82
E= 0.82 x 100
E= 82%Rate this question:
- 41.
Find the cost to use this appliance per month (assume 30 days), using the info below: kWh= $0.07 Toaster: 0.2 hours per day Power rating of 1000 W = $? (round to nearest hundreth place, just as real money)
Correct Answer
0.42
$0.42Explanation
The cost to use the toaster per month can be calculated by multiplying the power rating of the toaster (1000 W) by the number of hours per day it is used (0.2 hours), then multiplying that by the cost per kilowatt-hour ($0.07), and finally multiplying by the number of days in a month (30).
So, the calculation would be: (1000 W * 0.2 hours * $0.07/kWh * 30 days) = $0.42. Therefore, the cost to use the toaster per month is $0.42.Rate this question:
- 42.
A 850 W oven requires a 7A current. What is the voltage (round to nearest tenth)?
Correct Answer
121.4 V
121.4 volts
121.4V
121.4 VoltsExplanation
The voltage can be calculated using the formula P = IV, where P is the power in watts, I is the current in amperes, and V is the voltage in volts. Rearranging the formula to solve for V, we have V = P/I. Plugging in the values, we get V = 850 W / 7 A = 121.4 V. Therefore, the voltage is 121.4 V.Rate this question:
- 43.
Which of the following energy sources used in generating power is considered a fossil fuel?
- A.
Water
- B.
Biomass
- C.
Natural gas
- D.
Uranium
Correct Answer
C. Natural gasExplanation
Natural gas is considered a fossil fuel because it is formed from the remains of ancient plants and animals that were buried and subjected to high heat and pressure over millions of years. It is primarily composed of methane, a greenhouse gas, and is extracted from underground reservoirs. Natural gas is commonly used in power generation due to its high energy content and relatively low carbon emissions compared to other fossil fuels like coal and oil.Rate this question:
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- 44.
Nuclear waste is disposed of by...
- A.
Mixing with chemicals
- B.
Diluting with water
- C.
Burying underground
- D.
Sending it off into space
Correct Answer
B. Diluting with waterExplanation
Nuclear waste is disposed of by diluting with water to reduce its concentration and make it less harmful. This process is known as dilution. By mixing the waste with a large volume of water, the radioactive materials are spread out and their impact is minimized. This method is commonly used for liquid radioactive waste. However, it is important to note that dilution is not a permanent solution and further steps are required for long-term storage or disposal of nuclear waste.Rate this question:
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