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Capacitor with Dielectric and Effect of Inserting Slab

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15 questions

A parallel plate capacitor with \( C = 90 \, \text{pF} \) in air has a dielectric (\( K = 9 \)) inserted fully between p

**Potential difference increase** statement with constant charge is incorrect; V decreases when K>1 inserted. If slab inserted while maintaining constant charge, E reduces to E₀/K, V = E d reduces. If battery connected maintaining constant V, E stays V/d, D = ε E increases, Q increases K times. C' = K C = 9 × 90 = 810 pF . Using V = kQ/r, U = k q₁q₂/r, E = -dV/dr, C = ε₀A/d, 1/C_eq series, C_eq = ΣC parallel, U = ½ C V² and common potential V = Q_total/C_total, result 810 pF follows, reflecting potential-capacitance relations.

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

A parallel plate capacitor with \( A = 0.01 \, \text{m}^2 \), \( d = 1 \, \text{mm} \) has a dielectric (\( K = 5 \)). W

**Effect of dielectric** is to reduce effective field due to polarization, bound surface charges opposite to free charges, net field E = E₀ - E_p = E₀/K. Capacitance C = Q/V = K ε₀ A/d for full filling, partial filling C = ε₀ A/(d - t + t/K) for slab thickness t. C = (ε₀ K A/d) = (8.85 × 10⁻¹² × 5 × 0.01/10⁻³) = 4.425 × 10⁻¹⁰ F = 442.5 pF . Using V = kQ/r, U = k q₁q₂/r, E = -dV/dr, C = ε₀A/d, 1/C_eq series, C_eq = ΣC parallel, U = ½ C V² and common potential V = Q_total/C_total,

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

When a dielectric slab fills only half the space between the plates of a parallel plate capacitor (connected to a batter

**Effect of dielectric** is to reduce effective field due to polarization, bound surface charges opposite to free charges, net field E = E₀ - E_p = E₀/K. Capacitance C = Q/V = K ε₀ A/d for full filling, partial filling C = ε₀ A/(d - t + t/K) for slab thickness t. With a constant voltage V across the plates, the electric field E varies between regions. In the air region, Eₐir = (V/d) , where d is the plate separation. In the dielectric region ( K > 1 ), polarization reduces the field: Ediₑlₑctric = (Eₐir/K) = (V/K d) . Since K > 1

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

A dielectric slab is partially inserted between the plates of a parallel plate capacitor while maintaining a constant vo

**Effect of dielectric** is to reduce effective field due to polarization, bound surface charges opposite to free charges, net field E = E₀ - E_p = E₀/K. Capacitance C = Q/V = K ε₀ A/d for full filling, partial filling C = ε₀ A/(d - t + t/K) for slab thickness t. When a dielectric slab (with dielectric constant K > 1 ) is inserted between the plates of a capacitor with constant voltage V , the electric field E in the dielectric region decreases. The electric field in a dielectric is given by E = (E₀/K) , where E₀ = (V/d) is the field

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

A parallel plate capacitor with \( C = 70 \, \text{pF} \) in air has a dielectric (\( K = 5 \)) inserted fully between p

**Potential difference increase** statement with constant charge is incorrect; V decreases when K>1 inserted. If slab inserted while maintaining constant charge, E reduces to E₀/K, V = E d reduces. If battery connected maintaining constant V, E stays V/d, D = ε E increases, Q increases K times. C' = K C = 5 × 70 = 350 pF . Using V = kQ/r, U = k q₁q₂/r, E = -dV/dr, C = ε₀A/d, 1/C_eq series, C_eq = ΣC parallel, U = ½ C V² and common potential V = Q_total/C_total, result 350 pF follows, reflecting potential-capacitance relations.

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

When a dielectric slab is inserted between the plates of a charged parallel plate capacitor (disconnected from the batte

**Effect of dielectric** is to reduce effective field due to polarization, bound surface charges opposite to free charges, net field E = E₀ - E_p = E₀/K. Capacitance C = Q/V = K ε₀ A/d for full filling, partial filling C = ε₀ A/(d - t + t/K) for slab thickness t. When a dielectric slab (with K > 1 ) is inserted into a disconnected capacitor, the charge Q remains constant. The capacitance increases ( C' = K C ), and the potential difference decreases ( V' = V/K ). The energy stored is given by U = (Q²/2C) , so with increased C

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

A parallel plate capacitor with capacitance \( 300 \, \text{pF} \) has a dielectric (\( K = 3 \), thickness \( d/8 \)) i

**Potential difference increase** statement with constant charge is incorrect; V decreases when K>1 inserted. If slab inserted while maintaining constant charge, E reduces to E₀/K, V = E d reduces. If battery connected maintaining constant V, E stays V/d, D = ε E increases, Q increases K times. Potential difference: V = E₀ ( (7d/8) ) + (E₀/K) ( (d/8) ) = E₀ d ( (7/8) + (1/8 × 3) ) . V = E₀ d ( (7/8) + (1/24) ) = E₀ d × (22/24) = E₀ d × (11/12) . C = (Q/V) = (Q/(11/12) V₀) = (12/11) × 300 ≈ 327.27 pF

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

A parallel plate capacitor with \( C = 80 \, \text{pF} \) in air has a dielectric (\( K = 8 \)) inserted fully between p

**Potential difference increase** statement with constant charge is incorrect; V decreases when K>1 inserted. If slab inserted while maintaining constant charge, E reduces to E₀/K, V = E d reduces. If battery connected maintaining constant V, E stays V/d, D = ε E increases, Q increases K times. C' = K C = 8 × 80 = 640 pF . Using V = kQ/r, U = k q₁q₂/r, E = -dV/dr, C = ε₀A/d, 1/C_eq series, C_eq = ΣC parallel, U = ½ C V² and common potential V = Q_total/C_total, result 640 pF follows, reflecting potential-capacitance relations.

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

A parallel plate capacitor with \( C = 20 \, \text{pF} \) in air has a dielectric (\( K = 3 \)) inserted fully between p

**Dielectric slab inserted** into capacitor with constant charge Q increases capacitance C' = K C₀, K dielectric constant, so potential difference V' = Q/C' = V₀/K decreases K times. With constant voltage V maintained by battery, capacitance increase causes charge Q' = K Q₀ to increase, extra charge supplied by battery, energy changes. C' = K C = 3 × 20 = 60 pF . Using V = kQ/r, U = k q₁q₂/r, E = -dV/dr, C = ε₀A/d, 1/C_eq series, C_eq = ΣC parallel, U = ½ C V² and common potential V = Q_total/C_total, result 60 pF follows, reflecting potential-capacitance relations.

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

In a system where a positively charged sphere is enclosed by an uncharged conducting shell, why does the outer surface o

**Effect of dielectric** is to reduce effective field due to polarization, bound surface charges opposite to free charges, net field E = E₀ - E_p = E₀/K. Capacitance C = Q/V = K ε₀ A/d for full filling, partial filling C = ε₀ A/(d - t + t/K) for slab thickness t. The positively charged sphere induces a negative charge on the inner surface of the shell and a positive charge on its outer surface to maintain zero field inside the conductor. When a negative charge is brought near the shell, it repels negative charges to the far side of the shell and attracts positive

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

A parallel plate capacitor with \( C = 30 \, \text{pF} \) in air has a dielectric (\( K = 6 \)) inserted fully between p

**Dielectric slab inserted** into capacitor with constant charge Q increases capacitance C' = K C₀, K dielectric constant, so potential difference V' = Q/C' = V₀/K decreases K times. With constant voltage V maintained by battery, capacitance increase causes charge Q' = K Q₀ to increase, extra charge supplied by battery, energy changes. C' = K C = 6 × 30 = 180 pF . Using V = kQ/r, U = k q₁q₂/r, E = -dV/dr, C = ε₀A/d, 1/C_eq series, C_eq = ΣC parallel, U = ½ C V² and common potential V = Q_total/C_total, result 180 pF follows, reflecting potential-capacitance relations.

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab

A parallel plate capacitor with \( C = 40 \, \text{pF} \) in air has a dielectric (\( K = 5 \)) inserted fully between p

**Effect of dielectric** is to reduce effective field due to polarization, bound surface charges opposite to free charges, net field E = E₀ - E_p = E₀/K. Capacitance C = Q/V = K ε₀ A/d for full filling, partial filling C = ε₀ A/(d - t + t/K) for slab thickness t. C' = K C = 5 × 40 = 200 pF . Using V = kQ/r, U = k q₁q₂/r, E = -dV/dr, C = ε₀A/d, 1/C_eq series, C_eq = ΣC parallel, U = ½ C V² and common potential V = Q_total/C_total, result 200 pF follows, reflecting potential-capacitance relations.

Ref: NCERT > Physics Book > Electrostatic Potential and Capacitance > Capacitor with Dielectric and Effect of Inserting Slab