Circuit Builder Lab

Explore series, parallel, and combination circuits interactively. Adjust resistor values and battery voltage to see Ohm's Law, Kirchhoff's Voltage Law, and Kirchhoff's Current Law play out in real time — with animated SVG circuit diagrams and per-component V, I, P readouts.

Guided Experiment: Series Circuit Investigation

Hypothesis

Setup

Run Experiment

Analyze

Conclude

If you add a second resistor in series with the first, how do you predict total resistance and current will change?

Write your hypothesis in the Lab Report panel, then click Next.

Circuit Diagram

Wire thickness and color indicate current magnitude — thicker/redder = more current

Controls

Circuit Template

Presets

Battery Voltage9.0 V

Resistor Values

R1100 Ω

R2200 Ω

Results

R_total

300.00 Ω

I_total

0.0300 A

P_total

0.2700 W

KVL Residual (should be 0)

0.00e+0 V

Component	R (Ω)	V (V)	I	P
R1	100	3.000	0.0300 A	0.0900 W
R2	200	6.000	0.0300 A	0.1800 W
Battery	300.00	9.0	0.0300 A	0.2700 W

V = 9.0 \text{ V},\quad R_{total} = 300.0\,\Omega,\quad I = 0.0300 \text{ A}

Voltage Drops — Series

Dashed line shows battery voltage. Bars show voltage drop across each component — they must sum to the battery voltage (KVL).

Data Table

(0 rows)

#	Trial	Circuit	Battery(V)	R_total(Ω)	I_total(A)	P_total(W)

Hypothesis

0 / 500

Observations

0 / 500

Conclusions

0 / 500

Reference Guide

Ohm's Law

The fundamental relationship between voltage, current, and resistance in any resistive element.

V = IR

Where V is voltage in volts, I is current in amperes, and R is resistance in ohms. Power dissipated is:

P = IV = I^2 R = \frac{V^2}{R}

Series Circuits

Resistors in series share the same current. Total resistance is the sum of all resistances.

R_{total} = R_1 + R_2 + \cdots + R_n

The same current I flows through every component. Voltage divides proportionally to resistance: larger R gets a larger share of the battery voltage.

Parallel Circuits

Resistors in parallel share the same voltage. Total resistance is always less than the smallest branch.

\frac{1}{R_{total}} = \frac{1}{R_1} + \frac{1}{R_2} + \cdots + \frac{1}{R_n}

Current divides inversely with resistance — the path of least resistance carries more current.

Kirchhoff's Laws

KVL (Voltage Law): The sum of all voltage drops around any closed loop equals zero.

\sum V = 0 \quad \Rightarrow \quad V_{bat} = V_1 + V_2 + \cdots

KCL (Current Law): The sum of currents entering a node equals the sum leaving.

\sum I_{in} = \sum I_{out}