Skip to content
Login Register

#field cancellation

3 public questions tagged with this topic.

Coulomb's Law and Force Between Point Charges

Two charges \( +12 \, \mu\text{C} \) and \( -4 \, \mu\text{C} \) are 90 cm apart. What is the distance from \( +12 \, \m

**Coulomb's law** gives force between point charges as F = k·|q₁q₂|/r², k = 1/(4π ε₀) = 9×10⁹ N·m²/C², directed along line joining charges. Like charges repel, opposite attract, magnitude scales with product of charges and inverse square of separation r². Let x be distance from +12 μC , then 0.9 - x from -4 μC . (12 × 10⁻⁶/x²) = (4 × 10⁻⁶/(0.9 - x)²) , 12 (0.9 - x)² = 4 x² . 3 (0.81 - 1.8 x + x²) = x² , 2.43 - 5.4 x + 3 x² = x² . 2 x² - 5.4 x + 2.43 = 0 , x

Ref: NCERT > Physics Book > Electric Charges and Fields > Coulomb's Law and Force Between Point Charges

View Details
Coulomb's Law and Force Between Point Charges

Two charges \( +14 \, \mu\text{C} \) and \( -6 \, \mu\text{C} \) are 100 cm apart. What is the distance from \( +14 \, \

**Coulomb's law** gives force between point charges as F = k·|q₁q₂|/r², k = 1/(4π ε₀) = 9×10⁹ N·m²/C², directed along line joining charges. Like charges repel, opposite attract, magnitude scales with product of charges and inverse square of separation r². Let x be distance from +14 μC , then 1 - x from -6 μC . (14 × 10⁻⁶/x²) = (6 × 10⁻⁶/(1 - x)²) , 14 (1 - x)² = 6 x² . 14 (1 - 2 x + x²) = 6 x² , 14 - 28 x + 14 x² = 6 x² . 8 x² - 28 x + 14 = 0

Ref: NCERT > Physics Book > Electric Charges and Fields > Coulomb's Law and Force Between Point Charges

View Details
Electric Field and Electric Field Lines

What explains why the electric field due to a dipole can be zero at certain points along its equatorial plane?

**Electric field concept** visualizes influence of source charge. Uniform field exerts constant force F = qE, and flux Φ = E·A = E A cosθ links field to area orientation, maximum when field normal to surface. In the equatorial plane, the fields from the dipole’s positive and negative charges are equal in magnitude and opposite in direction at the midpoint. Their vector sum cancels out, resulting in a zero field at that specific location. Substituting values gives Field cancellation, 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 Field and Electric Field Lines

View Details