Ω is the symbol for the ohm — the unit of resistance, meaning how much a component opposes the flow of electric current. More ohms = harder for current to flow.
Series Circuits
Resistances add up:
Rtotal=R1+R2+R3+…R_{total} = something
Meaning: because there’s only one path, the current is forced through every resistor one after another — so the resistances stack up, making it harder overall.
- Current is the same everywhere: I = I1 = I2 = I3
Meaning: with only one path, the flow can’t split — the same amount of current passes through each component. - Voltage is shared between components (adds up to the supply voltage)
Meaning: the battery’s energy gets divided up across the resistors.
Example: Two 4 Ω resistors in series →4+4=8 Ω (double the path, double the difficulty)
Parallel Circuits
Resistances combine using reciprocals:
1Rtotal=1/R1+1/R2+1/R3+…
Meaning: each branch gives the current an extra route, so the overall path gets easier — even though every resistor still has its own resistance.
- Voltage is the same across each branch
Meaning: each branch connects directly across the battery, so every component gets the full push. - Current splits between branches: I total=I1+I2+I3
Meaning: the total flow entering the circuit divides among the paths, then rejoins.
Example: Two 4 Ω resistors in parallel →Rtotal1=4/1+4/1=2/1, so Rtotal = 2 Ω (two equal paths = half the difficulty)
Key Points to Remember
- Parallel resistance is always less than the smallest individual resistor — more paths always makes flow easier
- Series resistance is always more than the largest individual resistor — stacking resistors always makes flow harder
- Ohm’s Law: V= I×R, so I=VRI = I = RV
Meaning: the current you get equals the voltage (push) divided by the resistance - (push-back) — bigger push or less resistance means more current.
Worked Example
A 12 V battery with two 4 Ω resistors:
- Series: I =12/8 = 1.5A – the doubled resistance holds the current to 1.5 amps through everything
- Parallel: I =12/2 = 6 A total — the halved resistance lets 6 amps flow, splitting into 3 A through each branch
Ω (ohm) = the unit of resistance — how much a component opposes electric current. In circuits, the ohm is what determines how much current the battery can push through. The relationship between the resistances (in Ω) and the current (in amps) is what series and parallel rules are really about.
well we didn’t actually learn this yet well I did we have been learning about the circuit of a parallel and series and we haven’t learned this yet but maybe next time.











