Given below are two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R) Assertion (A): Copper is used to make electrical wires. Reason (R): Copper has very low electrical resistance. In the light of the above statements, choose the correct answer from the options given below.
Both A and R are true, and R is the correct explanation of A.
Understanding Assertion and Reason Questions
Assertion-Reason questions require you to evaluate two statements: an Assertion (A) and a Reason (R). You need to determine if each statement is true individually and then decide if the Reason correctly explains the Assertion.
Analyzing Assertion (A): Copper is used to make electrical wires
The Assertion states that copper is used to make electrical wires. Let's consider this statement:
- Electrical wires are used to conduct electric current from one point to another.
- Materials that conduct electricity well are called conductors.
- Copper is a metal known for being an excellent conductor of electricity.
- It is widely used in household wiring, power transmission cables, and many other electrical applications.
Based on common knowledge and the properties of materials, Assertion (A) is a true statement.
Analyzing Reason (R): Copper has very low electrical resistance
The Reason states that copper has very low electrical resistance. Let's consider this statement:
- Electrical resistance is a property of a material that opposes the flow of electric current.
- Materials with high resistance impede current flow, converting electrical energy into heat.
- Materials with low resistance allow electric current to flow easily with minimal energy loss. These are good conductors.
- Among common metals, silver is the best electrical conductor, but copper is very close and significantly less expensive. Aluminium is also used but has higher resistance than copper and requires thicker wires for the same current capacity.
- Therefore, copper indeed has a very low electrical resistance compared to many other materials.
Based on the electrical properties of copper, Reason (R) is also a true statement.
Evaluating if Reason (R) is the Correct Explanation for Assertion (A)
Now we need to determine if copper having very low electrical resistance (R) is the reason why it is used to make electrical wires (A).
- For electrical wires, we want a material that can carry electric current efficiently.
- Efficiency in electrical conduction means minimizing the loss of electrical energy during transmission.
- Energy loss in a conductor is primarily due to resistance, converting electrical energy into heat (Joule heating). The power dissipated as heat is given by $\text{P} = \text{I}^2\text{R}$, where I is the current and R is the resistance.
- A material with low resistance will cause less energy loss and less heating for the same amount of current.
- Therefore, the property of low electrical resistance is exactly what makes a material suitable for use as electrical wires, allowing current to flow efficiently with minimal energy waste and preventing excessive heating.
Since copper has very low electrical resistance, it is an excellent conductor, which is why it is preferred for making electrical wires. Thus, Reason (R) correctly explains Assertion (A).
Summary of Analysis
| Statement | Truth Value |
|---|---|
| Assertion (A): Copper is used to make electrical wires. | True |
| Reason (R): Copper has very low electrical resistance. | True |
| Does R explain A? | Yes |
Conclusion
Both the Assertion (A) and the Reason (R) are true statements, and the Reason (R) provides the correct explanation for the Assertion (A). Copper's low electrical resistance is precisely the reason why it is a favored material for electrical wiring.
Revision Table: Key Concepts
| Term | Definition/Explanation |
|---|---|
| Electrical Wire | A conductor used to transmit electric current. |
| Electrical Resistance | Opposition offered by a material to the flow of electric current. Measured in Ohms ($\Omega$). |
| Electrical Conductivity | A measure of a material's ability to conduct electric current. It is the reciprocal of resistivity. High conductivity means low resistance. |
| Conductor | A material that allows electric current to flow easily due to low resistance. |
Additional Information: Why Copper?
While silver is the best electrical conductor, its high cost makes it impractical for general wiring. Aluminium is another alternative, often used in high-voltage transmission lines due to its lighter weight and lower cost compared to copper, despite having higher resistance (about 1.6 times that of copper) and requiring larger cross-sectional areas for the same current capacity. Copper offers an excellent balance of low resistance, cost-effectiveness, ductility (can be easily drawn into wires), and tensile strength, making it the material of choice for most electrical wiring applications in buildings and appliances.
Important Questions from Assertion and Reason
Given below are two statements:
Statement I: Arithmetic Progression is a sequence in which the addition of any two consecutive terms is a constant.
Statement II: In a Geometric Progression, the ratio of any term to its preceding term is a constant.
In the light of the above statements, choose the most appropriate answer from the options given below.
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The filament in an electric bulb does not burn up although its temperature is about 2700°C when it glows.
Reason (R): Bulb filament is made of tungsten.
In the light of the above statements, choose the most appropriate answer from the options given below.
Given below are two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R).
Assertion (A): Diamond is used for cutting glass.
Reason (R): Diamond has a high refractive index.
Choose the most appropriate answer:
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Earth is the only planet known to have life.
Reason (R): Earth has an atmosphere which is a mixture of Oxygen, Nitrogen and Carbon dioxide.In the light of the above statements, choose the most appropriate answer from the options given below:
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Mercury is the second farthest planet from the Sun.
Reason (R): Mercury is the smallest planet in the entire solar system.
In the light of the above statements, choose the most appropriate answer from the options given below:
