Physics: Coulomb's Law and Electric Force

Coulomb's Law

• Describes the electric force between two point charges:
  • Like charges repel, opposite charges attract
  • Force is proportional to the product of the charges and inversely proportional to the square of the distance between them
  • Coulomb's Law equation: F = k * (q1 * q2) / r^2
    • F: electric force between the charges
    • k: Coulomb's constant (approximately 8.99 x 10^9 N m^2 C^2)
    • q1 and q2: magnitudes of the charges
    • r: distance between the charges

Electric Fields

• A vector field that surrounds charged particles
• Electric field lines:
  • emerge from positive charges and enter negative charges
  • are continuous and form closed loops
  • are denser near the charge and less dense farther away
• Electric field strength (E):
  • measured in N/C (newtons per coulomb)
  • proportional to the charge and inversely proportional to the square of the distance
  • Electric field equation: E = k * q / r^2
    • E: electric field strength
    • k: Coulomb's constant
    • q: magnitude of the charge
    • r: distance from the charge

Electric Potential

• The potential energy per unit charge at a given point in an electric field
• Electric potential (V):
  • measured in volts (V)
  • proportional to the charge and inversely proportional to the distance
  • Electric potential equation: V = k * q / r
    • V: electric potential
    • k: Coulomb's constant
    • q: magnitude of the charge
    • r: distance from the charge
• Equipotential surfaces:
  • surfaces where the electric potential is the same
  • perpendicular to the electric field lines

Gauss's Law

• Relates the distribution of electric charge to the resulting electric field
• Gauss's Law equation: ∫E · dA = Q / ε₀
  • ∫E · dA: total electric flux through a closed surface
  • Q: net charge inside the surface
  • ε₀: electric constant (approximately 8.85 x 10^-12 F/m)
• Key aspects:
  • The total electric flux through a closed surface is proportional to the net charge inside the surface
  • Electric field lines emerge from positive charges and enter negative charges

Coulomb's Law

• Describes the electric force between two point charges, stating that like charges repel and opposite charges attract
• The force is proportional to the product of the charges and inversely proportional to the square of the distance between them
• The equation for Coulomb's Law is F = k * (q1 * q2) / r^2, where F is the electric force, k is Coulomb's constant (approximately 8.99 x 10^9 N m^2 C^2), q1 and q2 are the magnitudes of the charges, and r is the distance between them

Electric Fields

• A vector field that surrounds charged particles
• Electric field lines emerge from positive charges and enter negative charges, are continuous and form closed loops, and are denser near the charge and less dense farther away
• Electric field strength (E) is proportional to the charge and inversely proportional to the square of the distance, measured in N/C (newtons per coulomb), and can be calculated using the equation E = k * q / r^2

Electric Potential

• The potential energy per unit charge at a given point in an electric field
• Electric potential (V) is proportional to the charge and inversely proportional to the distance, measured in volts (V), and can be calculated using the equation V = k * q / r
• Equipotential surfaces are surfaces where the electric potential is the same and are perpendicular to the electric field lines

Gauss's Law

• Relates the distribution of electric charge to the resulting electric field
• The equation for Gauss's Law is ∫E · dA = Q / ε₀, where ∫E · dA is the total electric flux through a closed surface, Q is the net charge inside the surface, and ε₀ is the electric constant (approximately 8.85 x 10^-12 F/m)
• The law states that the total electric flux through a closed surface is proportional to the net charge inside the surface, and that electric field lines emerge from positive charges and enter negative charges