15. Chapter 18: Direct-Current Circuits
Sources of emf and internal resistance
Resistors in series Req = R1+R2+…
Resistors in parallel Req = R1R2/[R1+R2]

16. Chapter 18: Direct-Current Circuits
Kirchhoff’s rules:
Junctions, branches and loops
Current in = current out at a junction
Sum of ΔV across all elements, around a closed loop is zero.
Watch out for signs and solve the equations.
Gives all currents and potential differences and power consumption

17. Chapter 18: Direct-Current Circuits
q = CV[1-exp(-t/RC)]
Charging
q = Q exp(-t/RC)
discharging
Timescale = RC