Question

The tendency of alternating current to concentrate near the surface of conductor is known as

• A. Skin effect
• B. Peltier Effect
• C. Fleming Effect
• D. Gauss Effect

Hint:

The skin depth (\(\delta\)) is inversely proportional to the square root of frequency (\(f\)), electrical conductivity (\(\sigma\)), and magnetic permeability (\(\mu\)). As frequency increases, skin depth decreases, and the skin effect becomes more pronounced.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
When direct current (DC) flows through a uniform conductor, the current density is uniform across its cross-section. However, when alternating current (AC) flows through a conductor, the current density decreases from the surface toward the center of the conductor.

Step 2: Detailed Explanation:
This phenomenon is known as theSkin Effect. It occurs due to self-induction within the conductor:

An alternating current produces a continuously changing magnetic field both inside and outside the conductor.

The inner concentric filaments of the conductor are linked by a greater amount of magnetic flux compared to the filaments closer to the surface.

This higher flux linkage in the inner filaments results in a higher self-inductance, creating a larger inductive reactance (\(X_L = 2\pi f L\)) at the center of the conductor.

Because current naturally takes the path of lowest electrical impedance, it concentrates near the outer boundary (the "skin") of the conductor where reactance is lower.

This reduces the effective cross-sectional area of the conductor, which increases its effective AC resistance compared to its DC resistance.
Let us review the other options for comparison:
-Peltier Effect: A thermoelectric phenomenon where heat is absorbed or released at the junction of two dissimilar conductors when an electric current is passed through them.
-Fleming Effect: A term sometimes historically associated with vacuum tubes or thermionic emission rules, not current distribution in conductors.
-Gauss Effect Law: A fundamental law of electromagnetism relating electric flux through a closed surface to the enclosed net charge.

Step 3: Final Answer:
The concentration of AC near the surface of a conductor is known as the Skin effect, which corresponds to Option (A).