VoltLab
The Journal
Ohm's Law Explained: Voltage, Current, and Resistance for Beginners
A plain-language walkthrough of V = I × R — what voltage, current, and resistance actually mean, how they relate, and how to use the triangle trick to rearrange the formula on the fly.
How to Read Resistor Color Codes (4-Band and 5-Band)
The standard resistor color code decoded band by band — what each color means as a digit, multiplier, or tolerance, and how 4-band and 5-band resistors differ.
Series vs Parallel Circuits: What's Actually Different
Why resistors add up in series but combine differently in parallel, with worked examples and the intuition for why a parallel combination is always smaller than its smallest part.
Choosing the Right Resistor for an LED: A Beginner's Guide
Why an LED needs a series resistor at all, how to calculate the right value from supply voltage and forward voltage, and how to round to a real, buyable part.
AA, AAA, 9V: A Beginner's Guide to Battery Types and Capacity
What mAh capacity actually means, how common battery sizes compare, and why a battery's real-world runtime is usually less than the simple math suggests.
The Science of Static Electricity: Why Balloons Stick to Walls
The triboelectric effect explained — how rubbing two materials together transfers charge, why a charged balloon sticks to a wall, and how the same idea scales up to a Van de Graaff generator.
Low-Voltage Electronics Safety for Beginners and Classrooms
Practical safety habits for battery-powered circuits and classroom static-electricity demos — what makes low voltage forgiving, what to double-check before powering up, and where to draw the line and call an electrician.
Ohm's Law, Rearranged Three Ways: Solving for Voltage, Current, or Resistance
Ohm's law isn't three formulas to memorize — it's one relationship you can solve for whichever quantity you don't already know. A drill-focused walkthrough of all three directions, with worked examples for each.
What Actually Happens When You Skip the LED Resistor
An LED without a series resistor doesn't just run "a bit bright" — it enters a runaway feedback loop that ends in seconds. The mechanism behind the rule, and what the resistor is really protecting against.
Reading Resistor Color Bands: Why the Tolerance Band Actually Matters
The tolerance band looks like an afterthought — one extra stripe at the end. It actually defines the real range a resistor's true value can fall in, and that range changes what a circuit can be trusted to do.
Series vs Parallel: What Each Wiring Actually Does to Current
Total resistance is only half the story. This is a closer look at current specifically — why it's identical everywhere in a series loop, why it splits unevenly in parallel, and how to verify both with real numbers.
Estimating Battery Life Honestly: Why the Math on the Label Lies a Little
Capacity divided by current draw gives an answer in seconds — and it's optimistic every time. A closer look at why real battery life falls short of the simple math, and how to estimate a number you can actually trust.