Key Terms
Definition
Each resistor connects directly to the voltage source. Multiple paths for current.
Total resistance
R_total = R1 + R2 + R3 + ...
Voltage drop across each resistor
V = IR (Ohm's law) The sum of all individual voltage drops equals the source voltage.
Total resistance formula
1/R_total = 1/R1 + 1/R2 + 1/R3 + ...
Process
Identify which resistors are in series, which are in parallel. Reduce each group to a single equivalent resistance.
Real-world implication
Wire resistance in series with parallel load resistors (like home appliances) causes a voltage drop in the wires. This r
Conservation check
Total power from the source equals total power dissipated by all resistors. Always.
EMF (electromotive force)
The potential difference of a source when NO current is flowing. Not actually a force - it's a voltage.
Terminal voltage
The actual output voltage when current IS flowing.
Terminal voltage formula
V_terminal = emf - I*r
As batteries age and deplete
R increases, terminal voltage drops, current capacity decreases.
Recharging
Requires applied voltage greater than the battery's emf to reverse current. V_terminal = emf + I*r when charging (curren
Mathematical form
I_in = I_out
Traversing a resistor in the direction of current
Potential change = -IR (drop) Traversing a resistor against the direction of current: potential change = +IR (rise) Trav
Voltmeter
Measures voltage; connected in PARALLEL with the component being measured.