Heres how I do circuits:
They will give you 2 kinds of circuits to analyze. Resistor circuits (includes bulbs, engines, etc) and Capacitor circuits. They will rarely give you RC circuits (resistor and capacitor together in one circuit). And RC circuits are a pain.
First you should know what series and parallel are.
Second there are 2 rules you should know: if the resistors or capacitors are in parallel, they are at the same voltage as the battery (receive different currents). If the resistors or capacitors are in series, they receive the same current from the battery (different voltage as the battery). Once you memorize these rules, it will make the circuit easy. Kirchkoff's rules state that current entering a junction equals exiting and voltage drops across the circuit add up to zero. The first rule means that current is not used up anywhere, so there is no loss of current. The second rule means that, all voltage produced by the battery creates the same total voltage drops across individual resistors/capacitors.
Third, you need to resolve the resistors or capacitors that are in parallel or series into one resistor or capacitor. How do you do that? There is a simple mnemonic I use..RASCAP. Resistors add in series and capacitors add in parallel. So, if you had 3 resistors in series, the total resistance will be R1 + R2+ R3. If the resistors are in parallel and the capacitors are in series, then you gotta use (R1 x R2)/ (R1 + R2)...same thing for capacitor
Fourth, ok so now you resolved everything into one. Now try finding the current through the one resolved object. V = IR. Plug in the voltage from the battery and the resolved resistance and find the current. Q = CV, use that to find the voltage for capacitors.
Lastly, once you found the current or voltage from step 4, go back and try to unresolve everything you just did. So the resistors u just added, become 3 resistors receiving the same (step 2) current I from step 4. Then use V = IR, to find the different voltages across individual resistors. For capacitors, all the capacitors in series receive the same current. If they give you time, use Q = I x T to find the total charge. Then use Q = CV to find the individual voltages. The same principles apply for resistors and capacitors in parallel, the only difference being that voltages will be same, so u gotta find the different currents for individual objects.
