4-Electric Circuits 2

Slideshow: RC circuits

Textbook: Not well represented in the textbook, but review Ch 16 for DC circuits.


  • Basically all the stuff from AP Physics 1, but now with capacitors included
    • resistivity depends on substance
    • use Kirchhoff's loop rules and junction rules to predict & test values (like power, potential difference and current) for resistors, capacitors and sources of EMF when changing their arrangement (parallel, series and combo)
    • Use Kirchhoff's rules as part of an explanation of energy and/or charge conservation
    • Analyze a non-ohmic resistor and internal resistance of a battery
    • Tell how capacitors work differently when first connected, when fully charged and when first connected in a discharging state.


Common Misconceptions

Simple Circuits

  • Resistors consume charge.
  • Electrons move quickly (near the speed of light) through a circuit.
  • Charges slow down as they go through a resistor.
  • Current is the same thing as voltage.
  • There is no current between the terminals of a battery.
  • The bigger the container, the larger the resistance.
  • A circuit does not have form a closed loop for current to flow.
  • Current gets "used up" as it flows through a circuit.
  • A conductor has no resistance.
  • The resistance of a parallel combination is larger than the largest resistance.
  • Current is an excess charge.
  • Charges that flow in circuit are from the battery.
  • The bigger the battery, the more voltage.
  • Power and energy are the same thing.
  • Batteries create energy out of nothing.

AC Circuits

  • Charges move all the way around a circuit and all the way back.
  • Voltage and current remain constant as in DC circuits.
  • Energy is not lost in a transformer.
  • A step-up transformer gives you something more for less input.
  • Transformers can be used to change DC voltages.
  • Electrical companies supply the electrons for your household current.

To Be Continued . . .