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Chapter 26
Direct Current Circuits
Introduction: Our approach
• EMF: Get more precise
• Consider combinations of resistors
• Understand circuits (with R and C) in
general with Kirchoff’s Laws
• Consider combinations of batteries
• Consider safe practices
EMF
• How do we distinguish between the emf of
a battery and its terminal voltage?
• What generally happens to the electrical
properties of a battery as it becomes
weaker?
Combinations of Resistors
• What is the equivalent resistance of
resistors in series?
• What is true about the currents through
and the voltages across each resistor?
• What is the equivalent resistance of
resistors in parallel?
• What is true about the currents through
and the voltages across each resistor?
Kirchhoff’s Rules
• What are the two basic physical ideas that
underlie the two Kirchhoff’s rules?
• What are the two Kirchhoff’s rules?
• To what end and how in general are they
applied?
RC Circuits
• How is a simple RC series circuit (battery,
resistor, capacitor in series) diagramed?
• Derive the equations representing what is
happening in this circuit.
• How is a proposed solution checked to
see if it is a solution?
• What is the form of the solution,
(mathematically and graphically)?
Combinations of Batteries
• What is the combined voltage and
equivalent internal resistance of batteries
in series and parallel?
• How should a strong battery be used to
help a weaker battery during a “jump
start”? Why?
Safety
• What are some safety practices around
electric currents and voltages?
• What is the physical basis for these
practices?
The End