Physics - Chapter 20

20.1 §

• Electric Field - Force field that exists around an electrically charged object
• E = $\frac{F}{q_o}$
  • magnitude of electric field = force on positive charge / amount of charge
  • SI Units: N/C
• F = qE
  • force = amount of charge x electric field
  • SI Unit: N
  • Equation gives magnitude AND direction to find magnitude only use F = |q|E
• E = k$\frac{|q|}{r^2}$
  • magnitude of electric field = k |charge|/(distance)${}^2$
• Electric Dipole - A system consisting of a positive and a negative charge
• Parallel-Plate Capacitor - A device consisting of two parallel plates (separated by a finite distance) that have opposite charges
• Charging by Induction - The charging of an object without direct contact

20.2 §

• Electric Potential Energy - Mechanical work that is stored as electrical energy
• Electric Potential - The charge in electric potential energy for a given amount of charge
  • change in electric potential = change in electric potential energy / charge
  • $△$ V = $\frac{△PE}{q}$
  • SI Unit: joule/coulomb = volt (V)
• Connection between the Electric Field and Electric Potential
  • electric field = - change in electric potential / distance
  • E = - $\frac{△V}{d}$
  • SI Units: volts / meter (V/m)
• Electric potential decreases in the direction of the electric field
• Energy is conserved in electrical systems
  • KE${}_A$ + PE${}_A$ = KE${}_B$ + PE${}_B$
• Electric Potential for a Point Charge
  • electric potential = k $\frac{charge}{distance}$
  • V = k$\frac{q}{r}$
  • SI Unit: Volt (V)

20.3 §

• Capacitor - A device that has the capacity to store electric charge and electrical energy
• Definition of Capacitance, C
  • capacitance = charge / electric potential difference
  • C = $\frac{Q}{V}$
  • SI Unit: coulomb / volt = farad (F)