# U10-Electric Circuits

Slideshow found here: Circuits Notes

Textbook: Chapter 16 in Mastering Physics (get online code for registration on about page of google classroom)

Basic Video tutorials from Dan Fulelrton: https://www.youtube.com/playlist?list=PLd2HWlWc-MszmgWIKnYCtN_3Heo1qroBi

Worked examples and concept tutorials from Mrs. Twu: https://sites.google.com/site/twuphysicslessons/home/circuits

### Essential Knowledge:

• ΔV=change in electrical potential energy per charge moving through a circuit
• ΣΔV=0 is used to explain conservation of energy in a circuit.
• ΔV=IR can be used to find ΔV for a single resistor using values of I and R for the resistor or for the overall circuit using the total I and equivalent resistance.
• Power is a rate of energy transfer and found using P=IV=ΔE/t. Individual resistors use energy (produce heat) as current runs through them.
• Charge flow is conserved in a closed system. This is demonstrated by the junction rule, where the sum of currents flowing into a circuit equal the sum of currents flowing of of a circuit.

### Student Objectives:

• Use circuit diagrams or descriptions to perform calculations of unknown values of current in different branches in a circuit.
• Kirchhoff's junction rule (ΣIin = ΣIout)
• Make claims and predictions about simple circuits based on conservation of charge.
• Compare currents in parallel branches using the junction rule/conservation of charge
• In particular, be prepared to discuss what would happen to branches if configurations are changed (double a resistor's value, open a switch, add a parallel path, etc)
• Design an experiment to show that charge is conserved in a parallel circuit. Plan data collection and analysis.
• Kirchhoff's loop rule (ΣΔV=0)
• construct or interpret a graph of energy changes within an electrical circuit
• design an experiment to demonstrate the validity of Kirchhoff's loop rule.
• consider how you would use a voltmeter on several components in series or possibly a simple combination circuit.
• Perform calculations using conservation of energy (loop rule)

### Common Misconceptions: (these statements all have errors)

• 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.