#elementary charge

Electric Dipole - Moment, Field and Torque

What property of electric charges explains why the smallest observable charge is that of an electron or proton?

**Interaction of dipole with uniform field** produces pure couple without net force, equal opposite forces forming torque. Potential energy minimum -pE at alignment, maximum +pE at anti-alignment, governing orientation dynamics. Quantization of charge means that charge exists in discrete units, with the smallest unit being the charge of an electron or proton ( e ). All observable charges are integer multiples of this fundamental unit, reflecting this property. Substituting values gives Quantization, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Dipole - Moment, Field and Torque

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Coulomb's Law and Force Between Point Charges

A plastic rod gains a charge of \( -1.28 \times 10^{-7} \, \text{C} \) when rubbed. How many electrons were transferred

**Electrostatic force** described by F = (1/4π ε₀)·q₁q₂/r² obeys Newton's third law. Magnitude depends on q₁q₂ and 1/r², enabling quantitative estimation at given separation, with sign indicating attraction or repulsion. Negative charge means electrons gained. q = n e , e = -1.6 × 10⁻¹⁹ C . n = (q/|e|) = (1.28 × 10⁻⁷/1.6 × 10⁻¹⁹) = 8 × 10¹¹ . Substituting values gives 8 × 10¹¹, 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 > Coulomb's Law and Force Between Point Charges

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Coulomb's Law and Force Between Point Charges

A body acquires a charge of \( -9.6 \times 10^{-8} \, \text{C} \) when rubbed. How many electrons were transferred to it

**Inverse-square law** for charges states F ∝ 1/r² while increasing with charge product. Using k = 9×10⁹ N·m²/C², force at distance r follows F = k q₁q₂/r², forming basis for pairwise force calculation. Negative charge indicates electrons gained. q = n e , e = -1.6 × 10⁻¹⁹ C . n = (q/|e|) = (9.6 × 10⁻⁸/1.6 × 10⁻¹⁹) = 6 × 10¹¹ . Substituting values gives 6 × 10¹¹, 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 > Coulomb's Law and Force Between Point Charges

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Electric Charge, Quantization and Conservation

A body gains a charge of \( -1.6 \times 10^{-7} \, \text{C} \) when rubbed. How many electrons were transferred to it?

**Quantization of charge** states observable charge is integer multiple of elementary charge e = 1.6×10⁻¹⁹ C, q = n·e, and total charge is conserved in isolated systems. Loss of electrons produces positive charge, and number of transferred electrons follows n = q/e, linking macroscopic charge measurement to microscopic carriers. Negative charge means electrons gained. q = n e , e = -1.6 × 10⁻¹⁹ C . n = (q/|e|) = (1.6 × 10⁻⁷/1.6 × 10⁻¹⁹) = 1 × 10¹² . Substituting values gives 1 × 10¹², which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's princi

Ref: NCERT > Physics Book > Electric Charges and Fields > Electric Charge, Quantization and Conservation

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Electric Charge, Quantization and Conservation

How many electrons must be added to a neutral body to give it a charge of \( -8 \times 10^{-8} \, \text{C} \)?

**Fundamental property of charge** includes additivity and quantization, meaning net charge equals algebraic sum of constituents and each is multiple of e. When rod loses charge, electron removal is inferred, and n = q/e gives transferred count. q = n e , e = -1.6 × 10⁻¹⁹ C . n = (q/e) = (-8 × 10⁻⁸/-1.6 × 10⁻¹⁹) = 5 × 10¹¹ . Substituting values gives 5 × 10¹¹, 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 Charge, Quantization and Conservation

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Electric Charge, Quantization and Conservation

A body loses \( 3.2 \times 10^{-8} \, \text{C} \) of charge when rubbed. How many electrons were transferred from it?

**Fundamental property of charge** includes additivity and quantization, meaning net charge equals algebraic sum of constituents and each is multiple of e. When rod loses charge, electron removal is inferred, and n = q/e gives transferred count. Losing charge means electrons are removed, so charge is positive. q = n e , e = 1.6 × 10⁻¹⁹ C . n = (q/|e|) = (3.2 × 10⁻⁸/1.6 × 10⁻¹⁹) = 2 × 10¹¹ . Substituting values gives 2 × 10¹¹, 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 Charge, Quantization and Conservation

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Electric Charge, Quantization and Conservation

A body loses \( 8.0 \times 10^{-8} \, \text{C} \) of charge when rubbed. How many electrons were transferred from it?

**Fundamental property of charge** includes additivity and quantization, meaning net charge equals algebraic sum of constituents and each is multiple of e. When rod loses charge, electron removal is inferred, and n = q/e gives transferred count. Losing charge means electrons are removed, so charge is positive. q = n e , e = 1.6 × 10⁻¹⁹ C . n = (q/|e|) = (8.0 × 10⁻⁸/1.6 × 10⁻¹⁹) = 5 × 10¹¹ . Substituting values gives 5 × 10¹¹, 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 Charge, Quantization and Conservation

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