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Gauss' theorem

ICSE · Class 12 · Physics

Flashcards for Gauss' theorem — ICSE Class 12 Physics. Quick Q&A cards covering key concepts, definitions, and formulas.

107 questions31 flashcards5 concepts

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31 Flashcards
Card 1Area vector

State the area vector.

Answer

Formula: A = A · n̂ Meaning: The area vector has magnitude equal to the area and direction along the outward normal. Unit: m² for area magnitude. Quick example: For a plane surface, the vector points

Card 2Electric flux

A plane surface of area 5 m² has its normal at 60° to a uniform electric field of 20 N/C. Find the electric flux.

Answer

Given: E = 20 N/C, A = 5 m², θ = 60° Formula: Φ_E = EA cosθ Step 1: cos 60° = 1/2 Step 2: Φ_E = 20 × 5 × (1/2) N·m²/C Step 3: Φ_E = 50 N·m²/C Answer: 50 N·m²/C

Card 3Electric flux

What is the electric flux through a plane surface parallel to the electric field?

Answer

For a plane surface parallel to the field, θ = 90°. Formula: Φ_E = EA cosθ Since cos 90° = 0, the flux is 0. Physical meaning: field lines do not pass through the surface normally. Example: A surface

Card 4Electric flux

State the definition and SI unit of electric flux.

Answer

Definition: Φ_E = ∫ E · dA for an open surface, and Φ_E = ∮ E · dA for a closed surface. Meaning: Electric flux is a measure of the number of field lines passing through a surface. SI unit: N·m²/C or

Card 5Gauss' theorem

A closed surface encloses a charge of 3 μC. Find the net electric flux through it.

Answer

Given: q = 3 μC = 3 × 10^-6 C Formula: Φ_E = q/ε₀ Take ε₀ ≈ 8.85 × 10^-12 C² N^-1 m^-2 Step 1: Φ_E = (3 × 10^-6)/(8.85 × 10^-12) N·m²/C Step 2: Φ_E ≈ 3.39 × 10^5 N·m²/C Answer: 3.39 × 10^5 N·m²/C

Card 6Gauss' theorem

State Gauss' theorem in integral form.

Answer

Formula: Φ_E = ∮ E · dA = q/ε₀ Meaning: The net electric flux through any closed surface equals 1/ε₀ times the net charge enclosed. Condition: It applies to a closed surface. Quick example: If enclose

Card 7Gauss' theorem

A point charge of 2 μC is enclosed by a spherical Gaussian surface. Find the flux through the surface.

Answer

Given: q = 2 μC = 2 × 10^-6 C Formula: Φ_E = q/ε₀ Step 1: Φ_E = (2 × 10^-6)/(8.85 × 10^-12) N·m²/C Step 2: Φ_E ≈ 2.26 × 10^5 N·m²/C Answer: 2.26 × 10^5 N·m²/C

Card 8Gauss' theorem

Why does a charge outside a closed surface produce zero net flux through that surface?

Answer

A charge outside the surface sends field lines into the surface at one part and out at another part. The inward and outward contributions cancel in the total flux. So, the net flux due to charge outsi

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Frequently Asked Questions

What are the important topics in Gauss' theorem for ICSE Class 12 Physics?
Key topics in Gauss' theorem include Gauss Theorem Concept Hierarchy, Gauss' Theorem Concept Map, Gauss' Theorem Concept Hierarchy. These are the concepts ICSE Class 12 examiners draw on most — study them first, then practise related questions.
How to score full marks in Gauss' theorem — ICSE Class 12 Physics?
Understand the core concepts first, then work through the 107 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.
How many flashcards are available for Gauss' theorem?
There are 31 flashcards for Gauss' theorem covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

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