AIIMS 2007 Physics Ohm's Law Assertion Reason Question

To analyze the given question regarding Ohm's Law, let's first understand what Ohm's Law states and its applicability.

Explanation of the Question

Assertion: Ω’s law is applicable for all conducting elements.
Reason: Ω’s law is a fundamental law.

Correct Answer: D) Both Assertion and Reason are false.

Understanding Ohm's Law

Ohm's Law states that the current ($I$) flowing through a conductor between two points is directly proportional to the voltage ($V$) across the two points, provided that the temperature remains constant. This relationship can be expressed mathematically as:

$$V = IR$$

where:

• $V$ is the voltage (in volts),
• $I$ is the current (in amperes), and
• $R$ is the resistance (in ohms).

Analysis of the Assertion

Assertion: Ω’s law is applicable for all conducting elements.

This assertion is false. Ohm's Law is applicable only to ohmic conductors, which exhibit a linear relationship between voltage and current. Examples of ohmic conductors include metals like copper and aluminum at constant temperatures. However, many materials, especially non-metallic conductors (like carbon or certain semiconductor materials) and at varying temperatures, do not obey Ohm's Law. These materials exhibit non-linear characteristics, hence Ohm's Law does not hold true for all conducting elements.

Analysis of the Reason

Reason: Ω’s law is a fundamental law.

This statement is also false. While Ohm's Law is a fundamental principle in the study of electrical circuits, it is not universally applicable. It is considered fundamental in the context of linear circuit analysis but does not apply to all materials, especially those where the relationship between current and voltage is non-linear.

Conclusion

Since both the assertion and the reason are false, the correct answer is D) Both Assertion and Reason are false.

Clarification of Other Options

• Option A: Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  Incorrect: Both statements are false.

• Option B: Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
  Incorrect: Both statements are false.

• Option C: Assertion is true but Reason is false.
  Incorrect: The assertion is false.

Summary

In summary, Ohm's Law is not applicable to all conducting materials, and while it is an important concept in physics, it is not a fundamental law in the sense that it holds universally across all materials. Therefore, both the assertion and reason are false, confirming that the correct answer is D.