#area

Electric Flux

A uniform electric field \( E = 3 \times 10^3 \, \text{N/C} \) is along the y-axis. What is the flux through a square of

**Electric flux** through surface measures field lines crossing it, Φ = E·A = E A cosθ for uniform field, unit N·m²/C. For circular area in xy-plane with field along z, θ = 0°, cosθ = 1, so Φ = E·πR² directly, maximum when field normal to surface. Area vector Δ S = (0.6)² = 0.36 m² along y-axis. Flux: Φ = E · Δ S = 3 × 10³ × 0.36 = 1080 N·m²/C . Substituting values gives 1080 N·m²/C, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Flux

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Electric Flux

A uniform field \( E = 9 \times 10^3 \, \text{N/C} \) is along the x-axis. What is the flux through a rectangle of 15 cm

**Flux definition** Φ = ∮ E·dA links field to area orientation. For uniform E perpendicular to surface, Φ = E A, with A = πr² for circle. Inclination reduces flux by cosθ factor, sign indicating outward or inward crossing. Area: A = 0.15 × 0.2 = 0.03 m² . Flux: Φ = E A cos 0° = 9 × 10³ × 0.03 = 270 N·m²/C . Substituting values gives 270 N·m²/C, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Flux

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Fluid Pressure, Pascal's Law and Manometers

A person stands on two bones, each with area 22cm2, exerting a total force of 588N. What is the average pressure on the

Pav = FA, F = 588N. Total area A = 2×22×10−4 = 4.4×10−3m2. Pav = 5884.4×10−3 = 1.33636×105Pa. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.34 × 10⁵ Pa. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: NCBI Bookshelf, Ideal Gas Law: P1V1/T1 = P2V2/T2.

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SI Units and Dimensional Formulae

If the unit of length is doubled, how is the unit of area affected?

Area is proportional to the square of length. So, if the unit of length doubles, the unit of area becomes four times larger. As per NCERT Class 11 Chapter 2, dimensional analysis checks correctness and SI units define base and derived quantities. This principle confirms that Four times is correct because its dimensions and unit match the physical quantity asked.

Ref: NCERT Class 11 Physics > Chapter 2: Units and Measurements > Topic: SI Units and Dimensional Formulae

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