# 4-Electric Circuits 2

## Slideshow: RC circuits

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

## Objectives:

• 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.

## Equations: ## 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.