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Concept module

Series and Parallel Circuits

Switch the same two loads between one loop and two branches, then track how current, voltage, brightness, and charge flow reorganize without changing the battery.

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Starter track

Step 5 of 60 / 6 complete

Electricity

Earlier steps still set up Series and Parallel Circuits.

1. Electric Fields2. Electric Potential3. Basic Circuits4. Power and Energy in Circuits+2 more steps

Previous step: Power and Energy in Circuits.

Start from track beginning

Why it behaves this way

Explanation

Series and parallel circuits use the same battery and the same loads, but the path structure is different. One series loop forces the same current through every load, while parallel branches let current split into separate paths and recombine later.

This module stays intentionally bounded to two loads and one topology toggle. That is enough to make current, voltage, brightness, and charge flow feel like one connected story without turning the page into a circuit-design tool.

Key ideas

01In series, the same current crosses both loads, so the battery voltage must be shared between them.

02In parallel, each branch spans the same two nodes, so both loads keep the full battery voltage while the branch currents depend on branch resistance.

03Brightness in this bounded model follows power. Equal bulbs are dimmer in series and brighter in parallel because the power in each load changes when the arrangement changes.

Frozen walkthrough

Step through the frozen example

Frozen walkthrough

Use the exact arrangement, resistances, and inspected time on screen. The same live circuit drives the loads, counters, overlays, and graphs below.

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Frozen valuesUsing frozen parameters

For the current circuit, what equivalent resistance does the battery feel, and what total current follows from that one-number load?

V

Battery voltage

12 V

R_{A}

Load A resistance

6 ohm

R_{B}

Load B resistance

6 ohm

1. Start from the live arrangement

This setup uses series loop, so

R_{eq} = R_{A} + R_{B}

2. Substitute the current load values

With

R_{A} = 6

and

R_{B} = 6

R_{eq} = 6 + 6

, so

R_{eq} = 12

3. Use Ohm's law on the whole circuit

I_{total} = \frac{V}{R _{eq}} = \frac{1}{2} 12

4. Compute the total current

That gives

I_{total} = 1

Equivalent resistance and total current

R_{eq} = 12, I_{total} = 1

Series adds the two loads into one path, so the equivalent resistance rises and the same loop current must pass through both loads.

Bulb-behavior checkpoint

Two identical bulbs are connected to the same battery. Why do they both look dimmer in series than in parallel even though the battery has not changed?

Make a prediction before you reveal the next step.

Predict whether each bulb gets less current, less voltage, or both before you switch the equal pair between the two arrangements.

Check your reasoning against the live bench.

In series, the same battery voltage has to be shared across the two bulbs, so the loop current is smaller and each bulb gets less power. In parallel, each bulb keeps the full battery voltage and therefore dissipates more power.

Brightness in this bounded model follows power. Series raises the equivalent resistance and lowers the loop current, while parallel lowers the equivalent resistance and lets each branch keep the full battery voltage.

Common misconception

Parallel makes bulbs brighter because the battery sends more voltage into each branch.

The battery voltage does not get stronger when the topology changes. In parallel, each branch simply keeps the full battery voltage because both branches connect across the same two nodes.

What really changes is the equivalent resistance seen by the battery. Lower equivalent resistance lets the same battery drive a larger total current.

Quick test

Compare cases

Question 1 of 5

Answer from the live circuit logic, not from detached rules. Each question asks what the stage, counters, or linked graphs must mean.

Two identical loads are connected to the same battery. Which statement best compares the equal series pair with the equal parallel pair?

Use the live bench to test the result before moving on.

Accessibility

The simulation shows one battery on the left and two bulb-like loads that can appear either in one series loop or in two parallel branches. A readout card on the right reports the live battery voltage, both load resistances, equivalent resistance, total current, branch currents, branch voltages, and branch powers.

Moving charge markers travel around the actual circuit path, and optional overlays add current arrows, voltage labels, shared-node markers, charge counters, and power badges that explain brightness. Compare mode adds a dashed ghost circuit for the second setup so arrangement changes stay visible on the same stage.

The page is intentionally bounded to one battery and two loads. There is no free-form circuit editor, so every displayed change stays tied to the same beginner-friendly current, voltage, branch, and power logic.

Graph summary

All three response graphs sweep only load B resistance while keeping the battery, load A, and arrangement fixed. The branch-current graph shows total current together with the two load currents, the branch-voltage graph shows how the two load voltages behave, and the load-power graph shows the live brightness logic for both loads.

The time rail still inspects the same stage honestly while the response graphs stay parameter-based. Pausing or scrubbing lets the learner compare charge counters and moving packets at one chosen time without changing the underlying graph sweep.

Keep the circuit path moving

Keep this idea moving

Open the next concept, route, or track only when you want the current model to widen into a larger branch.

Reduce the mixed circuitElectricity