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#external electric field

3 public questions tagged with this topic.

Energy Stored in Capacitor and Energy Density

Two charges \( 8 \, \mu\text{C} \) and \( -4 \, \mu\text{C} \) are at \( (-6, 0, 0) \) and \( (6, 0, 0) \, \text{cm} \)

**Energy stored in capacitor** U = ½ C V² = ½ Q V = Q²/(2C) (J), C capacitance (F), V voltage (V), Q charge (C). For 4 μF charged to 250 V, U=0.5×4×10⁻⁶×62500=0.125 J. Energy resides in electric field, energy density u = ½ ε₀ E² (J/m³), E field between plates. Mutual energy: U₁₂ = 9 × 10⁹ × (8 × 10⁻⁶ × (-4 × 10⁻⁶)/0.12) = -2.4 J . External potential: V(r) = (10⁵/r) , at r = 0.06 m , V = (10⁵/0.06) = 1.67 × 10⁶ V . External energy: 8 × 10⁻⁶ × 1.67 × 10⁶ + (-4 × 10⁻⁶) ×

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Energy Stored in Capacitor and Energy Density

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Conductors, Electrostatic Shielding and Dielectrics

Why does the electric field inside a dielectric material decrease when placed in an external field, compared to the fiel

**Conductor in electrostatic equilibrium** has E=0 inside, charges reside on surface, potential constant throughout conductor. Hollow shell with no internal charge has zero field inside cavity, even if external field present, charges on outer surface screen interior, principle used in Faraday cage. When a dielectric is placed in an external field E₀ , it polarizes, creating bound charges that produce an internal field Eiₙducₑd opposing E₀ . The net field inside the dielectric is E = (E₀/K) , where K > 1 is the dielectric constant. For linear dielectrics, K > 1 , so E < E₀ , as the polarization

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Conductors, Electrostatic Shielding and Dielectrics

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Conductors, Electrostatic Shielding and Dielectrics

Why is the electric field inside a hollow conducting shell zero when no charges are present inside, regardless of the ex

**Electrostatic shielding** inside hollow conducting shell field zero when no charges inside, regardless of external field, because free charges redistribute on outer surface to cancel external field inside conductor, E=0 inside material in equilibrium, consequence of Gauss's law and conductor property. In electrostatic equilibrium, the electric field inside a conductor is zero. For a hollow conducting shell, charges reside on the surfaces. If no charges are inside, applying Gauss’s law to a surface inside the shell shows no enclosed charge ( oint E · dA = (qₑₙc/ε₀) , qₑₙc = 0 ), so E = 0 insi

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Conductors, Electrostatic Shielding and Dielectrics

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