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What will be the current density of a metal if a current of 30A is passed through a cross-sectional area of 0.5m2?

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Answer & Explanation

Correct AnswerC. 60 A/m2

Quick Explanation

Current density is current per unit cross-sectional area. Thus J = I/A = 30/0.5 = 60 A/m².

Formula / Key Relation

J = I/A

J = 30/0.5 = 60 A/m²

Detailed Explanation

Concept & Reasoning

Current density describes how much current flows through a unit area normal to the current direction. For uniform current distribution, J = I/A. The area is already in square metres, so no unit conversion is required. Dividing 30 A by 0.5 m² gives 60 A/m².

How to Solve It in the Exam

Current density = current ÷ area.

Important Exam Point

Check that the area unit matches the required A/m² unit.

Related Revision Path

This question sits in the revision path Basic Electrical Engineering → Current and Current Density → Conduction .

Quick Trick

Current density = current ÷ area.

Common Mistake

Multiplying current by area reverses the physical relationship.

Exam Tip

Check that the area unit matches the required A/m² unit.

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Exam Path

Knowledge Path

Study concept · Current Density →Practice concept Practice topic

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